USMLE REVIEW 1

DANIL HAMMOUDI.MD

SINOE MEDICAL ASSOCIATION

ANAT:

Legend:

1. Sacro-spinal ligament
2. Sacro-tuberous ligament
3. Alcock's canal (or pudendal canal) with the pudendal nerve
4. Nerve of the clitoris
5. Perineal branch of the pudendal nerve
6. Anal branch of the pudendal nerve
7. Arcus tendineus fascia pelvis
8. Obturator muscle
9. Piriformis muscle
S2, S3 and S4: sacral roots forming the pudendal nerve

Right gluteal region

1. Reflected sacrotuberous ligament.
   2. Pudendal nerve entering the ischioanal fossa.
   
   Just superior to this point the pudendal nerve crossed the ischial spine. Anaesthetizing this nerve and the ilioinguinal nerve anaesthetizes the pudendum.

Nerve supply to perineum

The nerve supply to the perineum originates from three main sources:

1. The Genito-femoral Nerve (L1,L2).

2. The pudendal nerve arises from the anterior rami of the second to fourth sacral roots. These form a trunk before leaving the pelvis via the greater sciatic foramen. It passes immediately behind the ischial spine and swings forward to enter the perineum via the lesser sciatic foramen. The nerve passes through the ischiorectal fossa where it gives off its terminal branches. The inferior rectal nerve innervates the external anal sphincter and the perianal skin. The perineal nerve innervates the sphincter urethrae and other muscles of the anterior compartment via a deep branch, and the skin of the perineum poterior to the clitoris via its superficial branch. The dorsal nerve of the clitoris supplies the skin surrounding this structure.

3. The perineal branch of the posterior femoral nerve.

Pudendal Nerve Block

The palpating finger is used to locate the ischial spine and sacrospinous ligament per vaginam. The needle is inserted through the vaginal wall, is directed towards the spine and then passed through the sacrospinous ligament. As soon as the needle has passed through the ligament, a loss of resistance is felt. At this point 10mls of local anaesthetic solution (eg 1% Lignocaine with adrenaline) is injected after careful aspiration.

The perineal approach to pudendal nerve block. This approach is particularly useful when the head is fully engaged.

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• A TUMOR IN THE RIGHT JUGULAR FORAMEN =è SHOULDER DROOPè PATRALYSIS OF THE TRAPEZIUS MUSCLE INNERVATED PAR XI

THREE CRANIAL NERVE GO THROUGH THIS FORAMEN:

• -IX [GLOSSOPHARYNGEAL NERVE]
• -X [VAGUS NERVE]
• -XI [SPINAL ACCESSORY NERVE]

• JUGULAR VEIN EXIT THIS FORAMEN

X + IX ==è DYSPHAGIA + HOARSENESS

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Upper extremity:

Cephalic and Basilic veins are the superficial veins of the arm.

Basilic vein is the largest arm vein measuring 6 – 8 mm. Its course is along the medial (ulnar) aspect of the arm from wrist to shoulder. It begins at the dorsum of the hand, crosses the elbow and drains into the brachial vein.

Cephalic vein, measuring 4 – 6 mm, runs along the lateral (radial) aspect of the arm also from the wrist to shoulder emptying into the axillary vein.

Although the basilic vein is larger, the cephalic vein is more superficial and easier to dissect out. Therefore it is often the preferred vein for dialysis fistulas or grafts. 

Conversely, the cephalic vein may take an acute angle before it enters the axillary vein sometimes making negotiation with a catheter or wire difficult.

Both veins are good access for:

a. peripheral IV's

b. PICC lines

c. arm ports

Median vein:

Forms a Y just below the elbow and drains into both the basilic and cephalic veins.

Median antecubital vein:

Oblique coursing vein at the elbow that joins the basilic and cephalic veins.

Deep forearm veins:

These are 2 or 3 veins each that course with and are named like the corresponding arteries of the forearm (radial & ulna).

Brachial veins are the deep veins of the upper arm, usually paired and smaller than the superficial veins. They travel in the upper arm parallel to (on either side) the brachial artery and join with the basilic vein to form the axillary vein.

Brachial veins can be used for:

a. PICC lines

b. arm ports

Although not universal, many attempt placement of long term venous access between the elbow and the shoulder when using upper extremity veins. This avoids catheter irritation and compression from repetitive flexion at the elbow

Lower extremity:

Femoral Vein:

The femoral vein is the continuation of the popliteal vein beginning at the adductor hiatus. It receives the greater saphenous vein and the deep femoral vein. It continues as the external iliac vein at the inguinal ligament.

It usually lies posterolaterally to the femoral artery in the thigh and then moves medially at the groin. In approximately 25% of people the femoral vein is directly posterior to the artery at the groin.

Traditionally, femoral veins are not routinely used for venous access except on an acute temporary basis or when all other sites have been exhausted.

Theoretically,  the proximity to the groin increases the likelihood of contamination and infection. In addition, this location predisposes to catheter kinking and significantly affects ambulation.

Moreover, like other venous access sites, femoral catheters can cause thrombosis. The consequences of thrombosis  may have  greater clinical significance in the larger, dependent, lower extremity.

Despite these caveats, we have begun using this site for dialysis access in those patients with severely limited access and have had reasonable success.

 Femoral vein access – potentially more contamination and symptomatic DVT.

Chest and Neck:

Axillary Vein:

The axillary vein begins at the junction of the basilic and brachial veins. It runs medial, anterior and caudal to the axillary artery, to the lateral border of the first rib where it becomes the subclavian vein.

It lies caudal to the lateral half of the clavicle, slightly medial to and partly overlies the axillary artery. The artery and vein are within the axillary fascia. The brachial plexus (nerves) runs between artery and vein.

Valves may be present near the junction of the brachial and basilic veins.

Axillary vein access can be utilized to "prevent pinch off syndrome". This results from the more classical medial subclavian vein approach for central venous access (see complications for more information). If done from a lateral approach with sonography, axillary vein access can also decrease the incidence of pneumothorax.

The down side is that this approach, however, is that it still may incite the same amount of stenosis and thrombosis as the subclavian approach.

Subclavian Vein:

The subclavian vein runs from the lateral border of the first rib to the sternal end of the clavicle where it joins the internal jugular vein and becomes the brachiocephalic vein.

It lies posterior and superior to the subclavian artery.

A pair of valves is not uncommon at the termination of the subclavian vein.

The subclavian vein becomes the axillary vein at the lateral margin of the first rib.

The thoracic ducts enter the superior aspect of the subclavian vein near its junction with the internal jugular vein.

Access can be achieved via the anatomical landmark approach or with imaging. Using landmarks, an access needle is advanced medially along a horizontal plane beneath the medial 2/3’s of the clavicle towards the suprasternal notch of the manubrium.

As detailed under the procedure section, it is safer and more accurate to use imaging. In the case of the subclavian vein, venography or ultrasound can be utilized. Imaging permits a more lateral approach (axillary vein) which decreases the chance for pneumothorax and catheter compression from pinch off syndrome.

Additionally, structures such as the Phrenic nerve, brachial plexus and pleural cupola all lie within close proximity to the subclavian vein.

 Subclavian vein access is predisposed to both acute and chronic complications. (see complications)

We avoid this approach unless absolutely necessary.

In one report, using dialysis catheters, the complication rate for subclavian vein access was 44.2% higher than the internal jugular vein route. Anatomically, the right jugular provides a straight shot to the right atrium.  The right subclavian approach forces the catheter to abut up against multiple 'pressure points' in the vein.  In theory, the constant irritation from the catheter at these points could result in intimal hyperplasia and possibly explain the early failure of the sublavian access reported in the literature.

The pneumothorax rate is also higher from this approach as compared with the internal jugular vein. In addition, the infection rate for the subclavian vein route was more than twice the internal jugular vein.

Axillary and subclavian veins can be used for:

a. PICC line

b. Non-tunneled CVC

c. Tunneled CVC

d. Chest ports

Internal jugular vein (IJ):

The internal jugular vein exits the jugular foramen of the skull base and courses inferiorly along with the carotid artery and vagus nerve The IJ begins posterior to the carotid artery at the cranium but spirals around the artery and ends up anteriorly at the level of the chest. It lies between the two heads of the sternocleidomastoid muscle in the mid portion and finally lies posterior to the clavicular head of the muscle. It joins with the subclavian vein to become the brachiocephalic vein.

The IJ, especially the right side has become the preferred site for long term CVC’s.

 Reasons for (R) IJ preference for CVC’s:

a. superficial position

b. large size

c. high flow

d. greater distance from the lung

e. straight course to the SVC (catheter less likely to irritate venous endothelium)

f. less malposition

g. less stenosis and occlusion as opposed to the subclavian vein

f. direct compression of adjacent artery is easier if inadvertently punctured

Specifically in dialysis patients, internal jugular vein use protects the subclavian vein from catheter induced stenosis and occlusion which would preclude shunt placement on that side.

Percutaneous puncture of the subclavian and internal jugular vein was popularized by Stellato et al.

There are numerous anatomical landmark techniques for accessing the IJ. Commonly the carotid artery is manually displaced medially and a needle puncture is made midway between the angle of the mandible and superior margin of the clavicle directed towards the ipsilateral nipple.  

Normally the IJ vein lies lateral and slightly anterior to the carotid artery.

Because the course of jugular vein changes, the anatomic relationship between the IJ and common carotid artery is extremely variable. In addition the IJ may be small or thrombosed. Therefore, it is best to avoid potential complications by utilizing sonography for both the pre operative jugular vein assessment as well as direct visualization during the puncture.

Denys and Uretsky evaluated 200 consecutive patients with sonography and found that the IJ was normal size and position in 92%, non-visualized in 2.5%, and exceedingly small in 3%. Other studies including our own suggest that IJ variations from normal can occur in up to 28%.

Remember, variability among authors may relate to the level and degree of neck rotation when examined with ultrasound. As the neck is turned away from 30 to 90 degrees the IJ assumes a more anterior position in relation to the carotid artery.

The Valsalva maneuver or Trendelenburg position can increase the size of the IJ. If these maneuvers do not increase the IJ size, distal stenosis or obstruction should be considered.

Another caveat - extending the patient’s neck may actually flatten and decrease the size of the IJ vein.

When using ultrasound, the transducer orientation should be transverse to clearly differentiate between carotid artery and IJ.

The anatomic relationship of the internal jugular vein to the carotid artery varies. Sonography lessens the complications of inadvertent puncture and or cannulation of the carotid artery.  

Variable relationship of Internal Jugular Vein and Carotid Artery

External jugular (EJ):

The external jugular vein (EJ) begins approximately at the level of the angle of the mandible (from the junction of the posterior auricular and the retromandibular veins) and courses posterior to the sternocleidomastoid muscle to enter inferiorly into the subclavian vein.

Occasionally both the IJ and EJ may have incomplete or valve like structures.

Two sets of valves, tortuosity and course make the EJ less useful for venous access. Also, some EJ veins terminate in more of a plexus making catheter traversal difficult.

Some authors suggest that although it is not the most reliable route it is the safest.

Intercostal veins:

There are both anterior and posterior intercostal veins. The posterior division enters into the azygous and hemiazygous systems. The anterior division empties into the internal mammary vein. They lie beneath the ribs and serve as a collateral pathway in the presence of central deep venous thrombosis (DVT). As collaterals they may hypertrophy and be accessible for venous access.

Complications of access include PTX and damage to the neurovascular bundle.

Use of the external jugular and intercostal veins depends on their size.

a. PICC lines

b. Occasionally non-tunneled central lines

c. Rarely tunneled catheters

Abdomen:  

Inferior vena cava (IVC):

The IVC is formed from the junction of the common iliac veins at approximately the L5 level. It courses upwards towards the heart anteriorly and to the right of the spine. It lies to the right of the aorta and is oval in shape.

The renal veins enter the IVC at approximately the lower third of L1. The left renal vein enters slightly higher than the right. Both can be duplicated. IVC duplication .2%, Left renal vein duplication 11- 17%.

The IVC is commonly used for CVC’s when other sites are exhausted. It can be used for essentially any type of CVC but mostly for long term tunneled catheters. Considering the position of the IVC, be sure the CVC length is adequate.

The IVC can be accessed by either the translumbar or the transhepatic route.

Hepatic veins :

These consist of a right, middle and left. All three may join and enter the IVC as a common trunk but most commonly the right enters by itself and in 80% the middle and left hepatic veins have a common trunk.

The middle hepatic vein lies in the interlobar fissure separating the R and L lobes of the liver. The anterior course permits peripheral access.

Caudate veins (usually 2-3) drain separately into the IVC, several cm’s below the main hepatic veins.

Like the IVC the hepatic veins are recognized as a last resort type of access site. The middle hepatic vein is the most commonly chosen. It is most anterior and can provide a long intravascular course. This helps eliminate migration (withdrawl) of the catheter that occurs with respiration.

Any type of CVC can be placed.

Most prefer a subcostal approach to help avoid pneumothorax. Ultrasound can be utilized for localization and guidance if preferred. Once the hepatic vein is cannulated a guide wire is advanced to the IVC. The tract is serially dilated and a peel away sheath placed. As with other methods the catheter and tunnel length are determined and the catheter tip placed in the lower right atrium.

We also prefer the subcostal approach and use ultrasound to localize a hepatic vein. After appropriate patient preparation and local anesthesia we use an antegrade approach.

We connect a 10 cc syringe of diluted contrast to a 22 ga. Chiba needle and advance the needle towards the localized vein while injecting small volumes of contrast approximately every 0.5 cm. Using fluoroscopy, the hepatic vein is opacified and cannulated. This method also allows for needle redirection if a vital structure is transgressed. As before, we also "test the tract" before proceeding with catheter placement.

In addition, unless a specific catheter is required, we use a small (6 Fr.) self retaining catheter to avoid migration.

The major problem with this approach is catheter migration from normal respiratory motion.

Hepatic vein thrombosis has not been a clinical problem.

Infections unique to this approach have not been reported.

Collateral Veins:

Collaterals  form in response to more centrally occluded veins. Their purpose is to re-route blood back to the right atrium. They can occur anywhere but are common in the chest and neck. Because of their diminutive size and tortuous course they are usually best for PICC lines, however, small tunneled and non-tunneled lines are a possibility.

Collaterals are especially useful in individuals with a coagulopathy where other sites are more prone to bleeding.

Common collaterals employed include intercostal and chest wall veins.

When choosing a collateral vein for central venous access, it is important to be sure that it is not the last remaining draining vein in the event that it also becomes thrombosed.

Thrombosed Veins:

Many long-term central venous access patients have limited access due to thrombosis of previous sites. In these individuals it may be feasible to preserve the remaining access sites by negotiating through obstructed veins either for reconstruction of the vein or simple placement of a catheter.

Although these veins appear impenetrable, using sonography, guide catheters, hydrophilic guide wires and time, many can be negotiated. Once the occlusion is bypassed, the vein can be dilated using tapered Teflon dilators, Van Andel or balloon catheters. Occasionally, the CVC may be simply placed through the occlusion without dilatation.

Because these vessels have become essentially useless, complications are rare and if negotiation is unsuccessful, nothing is lost. Perforation is rare and often clinically inconsequential, however, proper technique should be employed to prevent this.

 The following is a technique that we find helpful in those chronic obstructions that allow passage of a guide wire but are so firm that they preclude traversal by a catheter. 

First gain access from above as usual and negotiate a wire through the obstruction. Next gain access from below, i.e. femoral vein, and snare the wire that has been negotiated through the obstruction. 

Next, place a dilator or tapered catheter over the guide wire from above and hemostat the wire just distal to the catheter hub. Now, pull the catheter through the occlusion by pulling the wire from the femoral access.

Thrombosed vein access can be used for all types of CVC’s.

Neck

Cervical Fasciae

• deep fascia of neck condenses to form four layers: investing, pretracheal, prevertebral, and carotid sheath

Investing Layer

• surrounds neck like collar
• splits to enclose two muscles (trapezius & sternocleidomastoid), two salivary glands (parotid & submandibular) and two spaces (suprasternal & supraclavicular)
• between angle of mandible and mastoid process, it splits into two laminae to enclose parotid gland, superficial lamina (parotid fascia) extends to zygomatic arch
• deeper lamina (between angle of mandible and styloid process) forms stylomandibular ligament
• forms roof of anterior and posterior triangles of neck

Attachments

• sup: ext. occipital protuberance, sup nuchal line, mastoid process, lower border of mandible
• inf: spine of scapula, acromion process, clavicle, manubrium
• post: ligamentum nuchae, C7
• ant: symphysis menti, hyoid bone

Pretracheal Fascia

• lies deep to infrahyoids
• splits to enclose thyroid, trachea and oesophagus

Attachments

• sup: hyoid bone, thyroid cartilage, cricoid cartilage
• inf: fibrous pericardium
• lat: ant layer of carotid sheath

Prevertebral Fascia

• situated in front of prevertebral muscles of neck (surrounds cervical vertebrae and associated muscles)
• forms floor of post. triangle of neck
• cervical and prox. brachial plexuses are deep to this fascia
• axillary sheath is extension of this fascia

Attachments

• sup: base of skull
• inf: body of T4
• inf & lat: axillary sheath

Carotid Sheath

• encloses common carotid and internal carotid arteries, internal jugular vein, and vagus nerve
• ansa cervicalis embedded in ant wall
• sympathetic chain lies post, outside sheath
• runs from base of skull to sup mediastinum

Root of Neck

• junctional area between neck and thorax
• key structures: thoracic inlet, cervical pleura, scalenus anterior
• oval shaped (transverse > A-P)
• plane: oblique (post higher than ant)

Boundaries

• post: T1
• lat: 1^st ribs and costal cartilages
• ant: manubrium sterni

Contents

Arteries

• right (r): brachiocephalic trunk, branches into r. subclavian and r. common carotid
• left (l): l. subclavian, l. common carotid

Brachiocephalic Trunk

• largest branch of arch of aorta, 4-5 cm in length and arises post to centre of manubrium
• passes sup and to right, post to sternoclavicular joint where it divides into r. subclavian a. and r. common carotid a.
• covered by sternohyoid and sternothyroid muscles

Subclavian

• is divided into three parts by scalenus anterior, it gives the following branches:
• Part 1 (med): vertebral, internal thoracic, thyrocervical trunk ( inf. thyroid, transverse cervical, suprascapular)
• Part 2 (post): costocervical trunk ( sup intercostal, deep cervical)
• Part 3 (lat): dorsal scapular, (occasionally suprascapular a)

Veins

• subclavian (from axillary v.), anterior to scalenus anterior
• internal and anterior jugular vv.

Anterior Jugular

• smallest of jugular veins, usually paired (joined by jugular venous arch just sup to sternum)
• arises near hyoid from confluence of submandibular veins (submental venous plexus)
• descends in superf fascia between mid line and ant sternocleidomastoid, turns lat at root of neck and opens into termination of ext jugular

Nerves

• phrenic n. (lat.)
• vagus + recurrent laryngeal
• sympathetic chain (med.)

Vagus

• leaves skull through jugular foramen with internal jugular vein and CN IX and XI
• descends in the carotid sheath
• on right: vagus crosses origin of subclavian a. (post to brachiocephalic vein) and gives off recurrent laryngeal n. which loops back around subclavian
• on left: recurrent laryngeal n. given off to loop around arch of aorta
• after looping both recurrent laryngeal nn. ascends to reach inf pole of thyroid where they ascend in tracheoesophageal groove to supply all intrinsic muscles of larynx except cricothyroid

Phrenic Nerve

• sole motor nerve to diaphragm
• it arises from C3,4,5 nerves
• it descends obliquely across the ant surface of scalenus ant, deep to prevertebral fascia
• crosses between subclavian v and a.. to enter thorax

Sympathetic Chain

• has three enlargements (ganglia), superior, middle, inferior
• inf: lies at sup 1^st rib, wrapped around vertebral a., usually fused with 1^st thoracic ganglion
• mid: lies on ant aspect of inf thyroid a. around level of cricoid cartilage (C6 vertebra)
• sup: located at level of atlas and axis, large (2-3 cm long)

Lymphatics

• left: thoracic duct
• right: r. lymphatic duct receives jugular, subclavian and bronchomediastinal lymph trunks

Viscera

• trachea
• oesophagus
• apex of lung with dome of pleura

Muscles

• longus colli
• sternal ends of sternocleidomastoid, sternohyoid, sternothyroid
• scalene muscles

Ligament

• ant. longitudinal lig.

Posterior Triangle of Neck

• triangular area in neck enclosed between sternocleidomastoid and trapezius

Boundaries

• base: mid ^1/3 of clavicle
• apex: lies on sup. nuchal line
• ant: post border of sternocleidomastoid
• post: ant border of trapezius
• roof: investing layer of cervical fascia
• floor: prevertebral fascia fascia covering splenius capitus, levator scapulae, scalenus medius, and scalenus posterior

Contents

• nerves: spinal accessory, cervical plexus (including phrenic), brachial plexus

• accessory n. (CN XI) divides post triangle into sup and inf parts, runs between sternocleidomastoid and trapezius (supplying both), enters at 1/3 way down sternocleidomastoid
• lesser occipital n. (C2) ascends short distance along sternocleidomastoid before it divides to supply skin of neck and scalp post to auricle, and sup auricle
• greater auricular n. (C2-3) curves over post sternocleidomastoid, supplies branches to skin of neck, divides into ant & post branch to supply inf auricle, and area from mastoid to mandible
• transverse cervical n. (C2-3) curves around the post border of sternocleidomastoid near its middle, passes transversely across it, supplies skin of ant triangle of neck
• supraclavicular nn. (C3-4) arise as single trunk, which divides into med, intermediate and lat branches
• phrenic n. (C3-5) curves around lat border of scalenus ant, descends obliquely across ant surface, deep to transverse cervical and suprascapular aa., enters thorax by crossing origin of internal thoracic a. between subclavian a. & v.

• arteries: subclavian (3^rd part), transverse cervical, suprascapular, occipital
• veins: external jugular, (subclavian)

• pierces and fuses with investing cervical fascia about 5 cm above clavicle
• if cut fascia prevents it from closing and can cause intravenous air embolus

• lymph nodes
• muscles

Muscle	Origin	Insertion	Innervation	Action
Splenius capitus	inf ligamentum nuchae, spinous processes of T1-T6	lat mastoid process and sup nuchal line	cervical spinal nn.	lat flexes head & neck, rotates head & neck to same side
Levator scapulae	transverse processes of C1-C4	sup med scapula	cervical spinal nn.	elevates scapula
Scalenus posterior	transverse process of C4-C6	2^nd rib	cervical spinal nn.	lat flexes neck, elevates 2^nd rib
Scalenus medius	transverse process of C2 & C7	sup post 1^st rib	cervical spinal nn.	lat flexes neck, elevates 1^st rib
Sterncleidomastoid	2 heads, sternal and clavicular	lat mastoid process, lat sup. nuchal line	CN XI	extend atlantio-occipital joint, flex cervical vertebrae

Subdivisions

• inf belly of omohyoid splits post triangle into large occipital triangle and small supraclavicular triangle

• occipital: occipital a. appears in its apex, contains important accessory n.
• supraclavicular: location indicated on neck by supraclavicular fossa, crossed by subclavian a. and external jugular v.

Anterior Triangle of Neck

• anterior triangle = triangular area on front of neck

Boundaries

• ant: midline
• post: ant border of sternocleidomastoid
• base: lower border of mandible, line drawn from angle of mandible to mastoid process
• apex: jugular notch

Contents

• muscles:

• suprahyoid muscles: mylohyoid (floor of mouth), geniohyoid (reinforce floor of mouth), stylohyoid (small slip on each side), digastric (straplike, two bellies, intermediate tendon joined to hyoid)
• infrahyoid muscles: omohyoid (two bellies, intermediate tendon joined to clavicle), sternohyoid (superf, except inf), sternothyroid (deep to sternohyoid), thyrohyoid (sup continuation of sternothyroid)

Muscle	Origin	Insertion	Innervation	Actions
Mylohyoid	mylohyoid line of mandible	hyoid	mylohyoid n. (branch of V3 n.)	elevates hyoid, floor of mouth and tongue
Geniohyoid	inf mental spine of mandible	hyoid	C1 n	pulls hyoid ant-sup, shortens floor of mouth, widens pharynx
Stylohyoid	styloid process	hyoid	facial n.	elevates and retracts hyoid
Digastric	ant belly: mandible post belly: mastoid process	intermediate tendon: hyoid	ant belly: mylohyoid n. post belly: facial n.	depresses mandible, raises and steadies hyoid
Omohyoid	Sup border of scapula	hyoid	ansa cervicalis	depresses, retracts and steadies hyoid
Sternohyoid	manubrium and med clavicle	hyoid	ansa cervicalis	depresses hyoid
Sternothyroid	post surface ofmanubrium	thyroid cartilage	ansa cervicalis	depresses hyoid and larynx
Thyrohyoid	thyroid cartilage	hyoid	C1.	depresses hyoid and raises larynx

• arteries: common carotid, internal carotid, external carotid + branches
• veins: ant jugular, int jugular + tributaries
• nerves: (IX), X, XI , XII, ansa cervicalis, sympathetic trunk
• viscera: pharynx, oesophagus, larynx, trachea
• glands: parotid, submandibular, thyroid, parathyroid

• submandibular fills most of digastric triangle, submandibular duct (5 cm) passes from deep process of gland to open on sublingual papilla

Subdivisions

• sup belly of omohyoid and digastric muscles subdivide anterior triangle into four smaller triangles: submental, digastric, carotid, and muscular

		Submental	Digastric	Carotid	Muscular
Boundaries		median triangle situated between ant bellies of digastric muscles and hyoid bone floor: mylohyoid muscle	ant: ant digastric post: post digastric sup (base): base of ant triangle floor: mylohyoid, hyoglossus, part of mid constrictor of pharynx	ant-inf: sup omohyoid post: ant sternocleidomastoid sup: post digastric & stylohyoid floor: thyrohyoid, hyoglossus, mid & inf constrictors of pharynx	bounded by ant sternocleidomastoid, sup omohyoid, median plane floor: infrahyoid muscles
Contents	Arteries		facial vessels mylohyoid vessels submandibular vessels carotid sheath + contents	common carotid int & ext carotid + branches (sup thyroid, asc pharyngeal, lingual, facial, occipital, post auricular)
	Veins	submental		int jugular + tributaries (facial, pharyngeal, lingual, sup & mid thyroid)
	Nerves		mylohyoid nerves CN IX, X, XII	CN IX, X, XI ansa cervicalis sympathetic chain	ansa cervicalis
	Muscles		hyoglossus mylohyoid		infrahyoid muscles (sternohyoid, omohyoid, sternothyroid, thyrohyoid)
	Other	submental lymph nodes	submandibular gland lower part of parotid gland	deep cervical lymph nodes carotid body	neck viscera
Notes				carotid sinus (baroreceptor) dilation of prox int carotid a., innervated by sinus branch of glossopharyngeal carotid body lies (chemoreceptor) lies behind, also supplied by sinus branch best site to approach big blood vessels in neck	all infrahyoids supplied by ansa cervicalis, except for thyrohyoid, supplied by C1

Midline of Neck

• between infrahyoid muscles are number of structures in and adjoining midline of neck

• hyoid bone
• median thyrohyoid ligament
• laryngeal prominence
• cricothyroid ligament
• cricoid cartilage
• cricothyroid muscle
• first tracheal ring
• isthmus and pyramidal lobe of thyroid
• inferior thyroid veins
• jugular venous arch (joins two anterior jugular vv.)
• thyroid ima a.

Blood Vessels

Arteries

Common Carotid Arteries

• r. common carotid begins at bifurcation of brachiocephalic, l. arises from arch of aorta (post to sternoclavicular joints)
• ascends within carotid sheath to level of sup border of thyroid cartilage where it terminates by dividing into int & ext carotid aa.

Internal Carotid Artery

• has no branches in neck, but are two of four major aa. that supply blood to brain
• each passes vertically upwards from common to enter carotid canal in petrous part of temporal bone, accompanied by plexus of sympathetic fibres
• during course through neck, lies deep to sternocleidomastoid m and parotid gland
• enters middle cranial fossa through the superior part of foramen lacerum
• supplies pituitary, orbit and most of supratentorial part of brain

External Carotid Artery

• extends between C3/C4 vertebra to the neck of the mandible
• runs midway between mastoid process and angle of mandible within the parotid gland
• terminates by dividing into two branches, maxillary a. and superficial temporal a.

Branches of External Carotid Artery

Surface	Branch	Notes
Anterior	superior thyroid	arises close to origin of ext carotid, just inf to greater horn of hyoid runs ant-inf (deep to infrahyoids) to reach sup pole of thyroid also gives off muscular branches to sternocleidomastoid and infrahyoid muscles, and sup laryngeal a.
	Lingual	arises from ext carotid where it lies on mid constrictor of pharynx arches sup-ant at the level of greater horn of hyoid) and n passes deep to hypoglossal n., stylohyoid and post digastric disappears deep to hyoglossus muscle, then on genioglossus to becomes deep lingual a.
	Facial	arise from ext carotid just sup to the lingual a. gives off tonsillar branch and branches to palate passes sup (under stylohyoid, digastric ), loops ant and enters deep groove in submandibular gland crosses inf border of mandible and enters face
Posterior	Occipital	arises near level of facial a., passes post along inf border of post belly of digastric, ends in post part of scalp, during course pass superf to int carotid a. and CN IX, X and XI
	post auricular	arise at sup post belly of digastric, ascends post of ext auditory meatus and supplies adjacent muscles, parotid gland, facial n. and scalp
Medial	asc. Pharyngeal	ascends on pharynx (deep to int carotid) and sends branches to pharynx, prevertebral muscles, middle ear and meninges

Veins

Internal Jugular Vein

• largest vein in neck (usually larger on right side than left)
• drains blood from brain and superf part of face and neck
• course corresponds to line drawn from external acoustic meatus to med end of clavicle
• commences at jugular foramen in post cranial fossa, as direct continuation of sigmoid sinus, from dilation at origin (sup bulb of int jugular v.) it runs in carotid sheath, leaves ant triangle by passing deep to sternocleidomastoid and unites with subclavian post to med clavicle
• inf bulb of int jugular v. located near termination, contains bicuspid valve
• tributaries: petrosal sinus, facial, lingual, pharyngeal, sup and middle thyroid and often occipital vv.

Thyroid Gland

• largest of endocrine glands
• consists of two lateral lobes, isthmus and occasionally pyramidal lobe

• isthmus overlies 2^nd, 3^rd and 4^th tracheal rings
• med lat lobe overlies larynx, trachea, oesophagus, inf. constrictor of pharynx and cricothyroid muscles
• post surface of lat lobe extends over carotid sheath
• infrahyoid muscles cover gland anteriorly

• levator glandulae thyroideae attaches pyramidal lobe to hyoid bone, embryological remnant of thyroglossal duct
• parathyroids are situated on post border, along line of sup and inf thyroid aa. Anastomoses
• arteries: sup thyroid a. (from ext carotid a.); inf thyroid a. (from thyrocervical trunk); and occasionally thyroid ima a.(from arch of aorta).
• veins: sup and middle thyroid vv.(empty into int jug v); inf thyroid vv (empty into brachiocephal v)

Clinical

• relation of isthmus to tracheal rings (tracheostomy)
• relation of ext laryngeal n. with sup thyroid a. (ligation of artery during thyroidectomy, hoarseness of voice because cricothyroid paralysed)
• relation of recurrent laryngeal n. with inf thyroid a. (ligation of artery during thyroidectomy, complete loss of voice as n. supplies all pharyngeal muscles except cricothyroid)
• remnant of thyroglossal duct may give rise to cyst (always located along ant midline of neck)
• close relationship of parathyroid to thyroid explain development of hypoparathyroidism is some patients following thyroidectomy

Pharynx

• funnel-shaped fibromuscular tube, common route for air and food
• located post to nasal cavity, mouth and larynx
• divided into three parts: nasopharynx, oropharynx, and laryngopharynx
• it is about 15 cm in length, extends from base of skull to inf border of cricoid cartilage
• widest (~5cm) opposite hyoid bone, narrowest (~1.5cm) at inf end
• post wall lies against prevertral fasica, with potential retropharyngeal space in between
• pharyngeal wall composed of five layers

• mucous membrane
• submucosa
• pharyngobasilar fascia (attached to skull)
• muscular layer composed of inner longitudinal (stylopharyngeus, palatopharyngeus and salpingopharyngeus) and outer ciruclar fibres (sup, middle and inf constrictors)
• loose connective tissue layer forming buccopharyngeal fascia

• supplied mainly by pharyngeal plexus of nn. (formed by CN IX (sensory) and X (motor)); nasopharynx receives its sensory supply mainly from CN V₃

Larynx

• air conducting tube, measures ~ 5 cm in length
• located in front of C3-C6 vertebrae below the hyoid bone
• cartilages: 3 single (epiglottis, thyroid, cricoid); 3 paired (arytenoid, corniculate, cuneiform)
• membranes and ligaments:

• extrinsic: thyrohyoid membrane, cricotracheal membrane
• intrinsic: quadrangular membrane (extends between epiglottis and vestibular folds); cricovocal membrane (extends between vocal ligament and upper border of cricoid cartilage)

Cavity

• divided into three parts:
• upper (vestibular) part; middle (ventricular) part: between vestibular and vocal folds; and lower (infraglottic) part
• rima glottidis: is the aperture between the two vocal folds.

Muscles of the Larynx

• extrinsic muscles that move the larynx up and down during deglutition:

• elevators of larynx : digastric, stylohyoid, mylohyoid, and geniohyoid muscles
• depressors of larynx : sternohyoid, sternothyroid, and omohyoid muscles

• instrinsic muscles: these are small muscles that move parts of the larynx on each other, and are particularly concerned with alterations in the length and tension of vocal folds in the production of voice, and in changing the size of rima glottidis to facilitate entry of air to the lungs

Nerves of the Larynx

• sensory nerve supply (to the mucosa) : above vocal fold: internal laryngeal nerve vocal fold: recurrent laryngeal nerve
• motor nerve supply (to intrinsic muscles) : recurrent laryngeal nerve, except for cricothyroid (supplied by external laryngeal nerve)

Head

Skull: Checklist of bones, sutures, features, and foramina

SKULL

Cranium (Brain case ) Facial skeleton

or Neurocranium

or Viscerocranium

Calvaria Cranial base

or Cranial Vault or Base of skull

or Upper part of brain case

The 8 Bones of cranium:

The 14 Bones of facial skeleton:

(4 single and 2 paired) (2single and 6 paired)

Frontal bone (single) Vomer (single)

Ethmoid bone (single) Nasal bone (paired)

Sphenoid bone (single) Lacrimal bone (paired)

Occipital bone (single) Inferior concha (paired)

Parietal bone (paired) Palatine bone (paired)

Temporal bone (paired) Zygomatic bone (paired) Maxilla (paired)

Mandible (single=two halves)

Skull : Exterior Views

1. Norma Verticalis ( Superior View ):

Bones Frontal

Parietals

Occipital ( squamous part )

Sutures : Coronal

Sagittal

Lambdoid

Frontal ( Metopic ) [occasional]

Features: Parietal eminence

Bregma

Lambda

Foramen: Parietal

2. Norma Frontalis ( Anterior View ):

Bones : Frontal

Nasal

Maxilla

Zygomatic

Features : Supercilary arches

Glabella

Nasion

Orbit

Anterior nasal aperture

Anterior nasal spine

Foramina:

Infraorbital

Zygomaticofacial

3. Norma Lateralis ( Lateral View ):

Bones : Frontal

Parietal

Sphenoid ( greater wing )

Temporal: ( squamous part , and zygomatic, mastoid and styloid processes)

Occipital

Zygomatic

Maxilla

Features: Pterion

Superior and Inferior temporal lines

Supramastoid crest

Temporal fossa

Infratemporal fossa

Pterygopalatine fossa

Foramina : External accoustic meatus.

Zygomaticotemporal foramen.

4. Norma Occipitalis ( Posterior view ):

Bones : Parietals

Occipital

Temporal ( mastoid part )

Sutures: Lambdoid

Parietomastoid

Occipitomastoid

Features: External occipital protuberance

Superior nuchal line

Inferior nuchal line

Inion.

5. Norma Basalis ( Inferior View ):

Bones: Maxilla: Palatine processes, alveolar processes

Palatine: Horizontal plate

Sphenoid: Body, greater wings, and medial and lateral pterygoid

plates.

Temporal: Squamous, petromastoid, and tympanic parts

Occipital: Basilar and squamous parts

Features: Incissive fossa

Posterior nasal spine

Pharyngeal tubercle

Pterygoid fossa

Scaphoid fossa

Pterygoid hamulus

Infratemporal crest

Spine of sphenoid

Mandibular fossa

Articular tubercle

Jugular fossa

Styloid process

Occipital condyle

Mastoid process

Mastoid notch (groove for posterior belly of digastric muscle)

External occipital crest

Superior and inferior nuchal lines

External occipital protuberance

Foramina : Incisive

Greater and lesser palatine

Foramen ovale

Foramen spinosum

Foramen lacerum

Opening for auditory tube

Carotid canal

Pterygoid canal

Foramen magnum

Hypoglossal canal

Jugular foramen

Stylomastoid foramen

Posterior nasal apertures (choanae)

Interior of the Skull

1. Inner aspect of the calvaria (vault)

Bones: Frontal

Parietal

Occipital

Features : Frontal crest

Groove for superior sagittal sinus

Groove for brances of middle meningeal vessels

Depressions for arachnoid granulations

Foramina: Parietal

B. Cranial Fossae:

1. Anterior Cranial Fossa:

Bones: Frontal (orbital plates)

Ethmoid (cribriform plate)

Sphenoid (lesser wings and jugum)

Features: Crista galli

Anterior clinoid process

Foramina: Cribriform plate foramina

Foramen caecum

Nasal slits

2. Middle Cranial Fossa:

Bones: Sphenoid (body and greater wings)

Temporal (petrous and squamous parts)

Parietal

Features: Sulcus chiasma

Sella turcica

Tuberculum sellae

Hypophyseal fossa

Dorsum sellae

Posterior clinoid processes

Groove (sulcus) for internal carotid artery

Middle clinoid process

Impression for the trigeminal ganglion

Foramina: Optic canal

Superior orbital fissure

Foramen rotundum

Foramen ovale

Foramen spinosum

Foramen lacerum

Fissures for greater and lesser petrosal nerves

3. Posterior cranial fossa:

Bones: Occipital (basillar and squamous parts)

Temporal (petrou..s and mastoid parts)

Parietal

Sphenoid (body)

Features: Groove for transverse sinus Groove for sigmoid sinus

Internal occipital crest

Internal occipital protuberance

Clivus

Foramina: Foramen magnum

Jugular foramen

Hypoglossal (anterior condylar) canal

Internal auditory (acoustic) meatus

Posterior condylar canal

.

Bones of the orbit

Margins of the orbit:

Medial: Frontal and maxillary bones

Superior: Frontal bone

. Lateral: Zygomatic and frontal bones

Inferior: Zygomatic and maxillary bones

Walls of the orbit:

Medial wall: Maxilla (frontal process)

Lacrimal bone

Ethmoid (orbital part)

Sphenoid (body)

Features: Nasolacrimal canal

Anterior and posterior ethmoid foramena

Roof (Superior) wall: Frontal (orbital plate)

sphenoid (lesser wing)

Features: Lacrimal fossa (for lacrimal gland)

Optic foramen

Trochlear fossa

Lateral wall: Sphenoid (anterior surface of the greater wing)

Zygomatic (orbital surface)

Features: Zygomatic canal (for zygomatic nerve from maxillary nerve)

Floor (Inferior) wall: Maxilla (orbital surface)

Zygomatic bone

Palatine bone (orbital process)

Features: Infra orbital groove and canal

*Superior Orbital Fissure: separates the lateral wall from the roof.

*Inferior Orbital Fissure: separates the floor from the lateral wall.

Pterygopalatine Fossa

Roof: Inferior surface of body of sphenoid

Orbitalprocess of palatine bone

Inferior orbital fissure

Floor: Apposition of anterior and posterior walls of the fossa

Anterior wall: Upper part of posterior surface of maxilla

Posterior wall: Anterior surface of greater wing of sphenoid

Root of pterygoid process

Anterior opening of pterygoid canal

Medial wall: Upper part of perpendicular plate of palatine bone

Orbital and sphenoidal processes of palatine bone

Sphenopalatine foramen

Mandible

1. Body: Surfaces ( external and internal )

Borders ( upper and lower )

Mental protuberance

Mental tubercle

Mental foramen

Oblique line

Digastric fossa

Mylohyoid line

Submandibular fossa

Sublingual fossa

Mental spines

Mylohyoid groove

2. Ramus: Surfaces ( lateral and medial )

Borders ( anterior and posterior )

Mandibular notch

Coronoid process

Condylar process ( head and neck of the mandible )

Angle of the mandible

Mandibular canal

Lingula

Foramina of Middle Cranial Fossa

Optic Canal	CN II, ophthalmic artery, central retinal vein
Superior Orbital Fissure	CN III, IV, VI, ophthalmic vein
Foramen Rotundum	CN V2 ( maxillary br.)
Foramen Ovale	CN V3 (mandibular br.)
Foramen Spinosum	middle meningeal artery
Foramen Lacerum	nothing

* all structures pass through sphenoid bone

 Foramina of Posterior Cranial Fossa

Internal auditory meatus	CN VII, VIII
Jugular foramen	CN IX, X, XI, jugular vein
Hypoglossal canal	CN XII
Foramen magnum	spinal root of CN XI, brain stem , vertebral artery

* all structures pass through  temporal & occipital bone

Passage of Cranial Nerves

CN I	Cribriform plate
CN II	Optic canal
CN III, IV, V1, VI	Superior orbital fissure
CN V2	Foramen rotundum
CN V3	Foramen ovale
CN VII, VIII	Internal auditory meatus
CN IX, X, XI	Jugular foramen

Mastication muscles

• 3 muscles to close jaw  : masseter, temporalis, medial pterygoid
• 1 muscle to open jaw   : lateral pterygoid
• All are innervated by  CN V3

3 Structures in Carotid sheath

• V  :  internal jugular vein ( lateral )
• A  :  common carotid artery ( medial )
• N  :  vagus nerve ( posterior )

Diaphragm
Embryology	septum transversum pleutoperitoneal folds dorsal mesentery of esophagus body wall
Passage	At T 8	Inferior vena cava
	At T10	esophagus, vagus
	At T12	aorta, thoracic duct, azygous vein
Innervation	C3,4,5 : Referred pain to shoulder

8 Layers of Abdomianl wall	Spermatic cord
Skin
Fascia ( Camper's & Scarpa's )	Dartos muscle & Colles' fascia
Ext. Oblique muscles	Ext. spermatic fascia & superficial inguinal ring
Int. Oblique muscles	Cremaster muscle & conjoint tendon
Transeverse abdominalis	No contribution except to conjoint tendon
Transverse facisa	Internal spermatic fascia & deep inguinal ring
Extraperitoneal fat
Peritoneum	Tunica vaginalis testis & processus vaginalis

Inguinal Hernia
Direct Hernia	Protrude through inguinal ( Hasselbach's) triangle Bulge directly through abdominal wall medial to inf. epigastric artery Goes through the superficial inguinal ring only
Indirect Hernia	Due to failure of closure of processus vaginalis Enters deep inguinal ring lateral to inf. epigastric artery Goes through deep & superficial inguinal ring, and into scrotum
Hasselbach's triangle	Inguinal ligament Inferior epigastric artery Lateral border of rectus abdominalis

Clinical Landmarks
Ischial spine	Pudendal nerve block
McBurney's point	Appendix 2/3 of the way between umblicus & Superior iliac spine
Iliac crest	Lumbar pucture

Hand Muscle : Thenar - Hypothenar
Thenar	Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis
Hypothenar	Opponens digiti minimi Abductor digiti minimi Flexor digiti minimi

Contents of femoral sheath

lateral to medial

femoral nerve, artery, vein, lymphatics

femoral nerve lies outside femoral sheath

femoral canal contains deep inguinal lymph node

Unhappy triad of Knee injury

• Common for football injury ( by clipping from the side )
• Injury of medial collateral ligament, medial meniscus, anterior cruciate ligament

Anterior Drawer sign : indicate tearing of ant. crucate ligament

Muscle name with Palate

• Innervation by Vagus nerve , but tensor veli palatini --> CN V3

KLM sounds
Kuh- kuh-kuh	test palatal elevation	vagus nerve
La- la- la	test tongue	hypoglossal nerve
Mi- mi- mi	test lips	facial nerve

Muscle name with ~Glossus

• Innervation of hypoglossal nerve, but palatoglossus --> vagal nerve

Cervical rib

• An embriological defect ;  can compress subcalvian artery and inferior trunk of branchial plexus (C8, T1), resulting in thoracic outlet syndrome

• Atrophy of the thenar and hypothenar eminences
• Atrophy of the interosseous muscle
• Sensory deficits on the medial side of the forearm and hand
• Disappearance of the radial pulse upon moving the head toward the opposite side

Medial nerve injury
Motor deficit	no loss of power in any of arm muscle loss of forearm pronation, wrist, and finger flexion several thumb movement, thenar atrophy
Sensory deficit	loss of sense in lateral palm, over thumb, radial 2 finger

Ulnar nerve injury
Motor deficit	impaired wrist flexion & adduction impaired adduction of thumb & ulnar 2 fingers

Radial nerve injury
Motor deficit	triceps brachi ( triceps reflex ) brachioradialis ( brachioradialis reflex ) extensor carpi radialis longus
Sensory deficit	posterior brachial cutaneous dorsal antebrachial cutaneous

Axillary nerve injury
Motor deficit	loss of deltoid action

Musculocutaneous nerve injury
Motor deficit	loss of function of coracobrachialis, biceps & brachialis muscle ( biceps reflex )      affect flextion at the shoulder (coracobrachialis & biceps brachii) flexion at elbow (brachialis , biceps brachii ) supination of forearm ( biceps brachii )
Sensory deficit	below elbow, continue as lateral cutaneous nerve of forearm no distribution to hand

Erb- Duchenne palsy
Cause	Traction or tear of the superior trunk of the brachial plexus (C5 & C6 roots) ; follows falling down on shoulder or trauma during delivery
Findings	limb hangs by side ( paralysis of abductors ) medially rotated ( paralysis of lateral rotators ) forearm is pronated ( loss of biceps )

Nerve injury in lower limbs
Common peroneal nerve	loss of dorsiflexion ( foot drop )
Tibial nerve	loss of plantar flexion
Femoral nerve	loss of knee jerk
Obturator nerve	loss of hip adduction

Pectinate line
Above the line	internal hekmorrhoid ( not painful ), adenocarcinoma visceral innervation, blood supply, and lymphatic drainage
Below the line	external hemorrhoid ( painful ), squamous cell ca, Somatic innervation, blood supply & lymphatic drainage

Portal - systemic anastomosis
Esophageal varices	left gastric --- azygous
Hemorrhoid	superior --- middle / inferior rectal
Caput medusae	paraumbilical --- inferior epigastric

Recurrent laryngeal nerve
Supplies all intrinsic muscles of the larynx except the cricothyroid muscle.
Left recurrent laryngeal nerve	wraps around the aortic arch and the ligamentum arteriosum
Right recurrent laryngeal nerve	wraps around right subclavian artery.
Damages results in hoarseness as a complication of thyroid surgery.

Lung relations

• Right lung has three lobes. Left has two lobes and Lingula ( homologue of right middle lobe ).
• Right lung more common site are for inhaled foreign body owing to less acute angle of right main stem bronchus

• Relation of pulmonary artery to the bronchus at each lung hilus : RALS ( Right-Anteior, Left-Superior )

• Bronchial & Pulmonary artery run with airways in the center, veins and lymphatics drain along the border

Course of ureter 

• pass under artery & under ductus deferens

Autonomic innervation of penis
Erection	by parasympathetic nervous system  ( Point )
Emission	by sympathetic innervation ( Shoot )
Ejaculation	by somatic & visceral nerves

Ligaments of the uterus

• pubocervical, transverse cervical ( cardinal ), sacrocervical ligaments, round ligament of uterus, round ligament of ovary
• round ligament of uterus  : homologous to gubernaculum testis; run from labia majora to uterus
• round ligament of ovary  : run from uterus to ovary
• broad ligament contains the round ligaments of the uterus, the round ligaments of the ovary, the uterine tubes, the epoophoron and multiple lymphatic vessels & nerve fibers

_____________________________________________________________________________________

Skull

• skeleton of head most complex bony structure in body, it encloses brain, houses organs of special senses, and surrounds openings into respiratory and digestive tracts
• in anatomical position, skull orientated so that inf margin of orbit and sup margin of external auditory meatus are level (orbitomeatal plane, Frankfort plane)

Anterior Aspect

• comprises ant part of calvaria superiorly and skeleton of face inferiorly
• notable features are forehead, orbits, prominence of cheek, anterior nasal apertures, paired maxillae, and mandible
• can be divided into five areas: frontal, orbital, maxillary, nasal and mandibular

Posterior Aspect

• formed mainly by paired parietal bones and occipital bone, meet mastoid parts of temporal bones laterally
• most prominent feature is rounded post pole, occiput, this region often referred to as occipital area
• external occipital protuberance is median projection, easily palpable at sup end of med furrow of neck

• centre and most prominent projection called inion

• curved superior nuchal lines run lat from ext occipital protuberance towards mastoid processes, represent sup limit of post neck, indicated where certain neck muscles attach
• post part of sagittal suture and lambdoid sutures meet at lambda

Superior Aspect

• oval shaped, broadened post by parietal eminences
• superciliary arches of frontal bone from ant limit, zygomatic arches visible laterally
• four bones united by interlocking sutures

• two parietal bones joined by sagittal suture
• frontal and parietal bones joined by coronal suture
• parietal and occipital bones joined by lambdoid sutures

• intersection of coronal and sagittal sutures is called bregma
• vertex, most sup part of skull, located near centre of sagittal suture
• parietal foramina located in parietal bone on each side of sagittal suture, transmit emissary veins which connect intracranial dural sinuses with veins covering skull

Inferior Aspect

• external surface of cranial base shows maxilla, bony palate, maxillary teeth and zygomatic arches
• each zygomatic arch formed by union of zygomatic bone and zygomatic process of temporal bone
• centrally, inf surface of cranial base irregular due to many foramina, processes and articulations, makes it weak and prone to fractures
• lat, cranial base exhibits temporal bones with prominent mastoid and styloid processes
• foramen magnum, bordered lat by occipital condyles (articulate with C1), transmits medulla oblongata

Lateral Aspect

• includes parietal, frontal and parts of temporal and sphenoid bones
• division of skull into calvaria and facial skeleton clearly shown

• calvaria formed by frontal bone (ant), sphenoid and parietal bones (lat), and occipital bone (post)

• pterion (where all four bone articulate) is important clinical landmark (ant branch of mid meningeal a. lies beside), located in temporal fossa

• located 2 fingers sup to zygomatic arch, 1 thumb post to zygomatic process of frontal bone

• other features are external auditory meatus, zygomatic bone, zygomatic arch, mastoid process and mandible

• mastoid process project ant-inf, med to ear lobe, easily palpable, size varies with muscularity and age (not present at birth, enlarge at puberty), form part of sup attachment of sternocleidomastoid

• mental protuberance (of chin) easily visible in most people

Internal Aspect

• bones seen in internal aspect of skull are: frontal, ethmoid, sphenoid, temporal and occipital
• internal surface of calvaria fairly smooth and concave, particularly from side to side
• striking features are grooves in parietal bones made by ant branches of mid meningeal blood vessels
• sutures least distinct on inside because fusion begins ~10 years earlier
• arachnoid granulations project into venous sinuses (particularly into lacunae of sup sagittal sinus) enough to indent bones of calvaria
• presents three distinct tiered areas: anterior, middle, and posterior cranial fossae

Walls

• thinner in females, young and old
• tends to be thinnest in areas that are well covered by muscles
• most bones of calvaria consist of inner and outer layers (tables) of compact bone, separated by layer of spongy diploë (containing red bone marrow)

Bones of Calvaria

• except for mandible and auditory ossicles bones of skull are joined by rigid sutures
• cranium is essentially one big complex bone

Frontal Bone

• frontal squama = smooth, board, convex plate of bone forming forehead
• the two halves halves of frontal squama are divided by metopic (frontal) suture in foetal skulls, begins to fuse during infancy and is not usually visible after 6 years of age
• frontal bone forms thin roof of orbits
• just sup to and parallel to each supraorbital margin is bony ridge called superciliary arch, which overlies frontal sinus
• gently rounded glabella lies between the two arches
• slightly prominences on each side (sup to superciliary arches) are frontal eminences
• supraorbital notch (foramen) (transmits supraorbital vessels and nerve) located in med supraorbital margin
• articulates with nasal bone at frontonasal suture

• at point where this crosses internasal suture is an anthropological landmark, nasion
• this isdepression in root of nose, where it joins cranium

• also articulates with zygomatic, lacrimal, ethmoid and sphenoid bones

Parietal bones

• form large parts of wall of calvaria

Face

• face extends from margin of hair to chin, from one auricle to or
• forehead common to both face and scalp
• skin contains numerous sweat and sebaceous glands and is connected to underlying bones by loose ct
• superficial fascia lies beneath skin with muscles of facial expression are embedded in it

Sensory Nerves

• include branches from three division of trigeminal n., which supply skin of face (except for small area over angle of mandible and parotid gland supplied by greater auricular n., C2-3)

Ophthalmic Nerve (V¹)

• superior division of trigeminal nerve
• wholly sensory and supplies skin derived from frontonasal prominence
• divides into three branches just before entering sup orbital fissure: nasociliary, frontal and lacrimal

Nasociliary

• supplies tip of nose through external nasal branch of anterior ethmoidal n.
• supplies root of nose through infratrochlear n.

Frontal

• direct continuation of V¹
• divides into two branches: supraorbital (med) and supratrochlear (lat)

Lacrimal

• smallest of main ophthalmic branches
• emerges over sup-lat orbital margin to supply the lat part of upper eyelid

Maxillary Nerve (V²)

• intermediate division of trigeminal nerve
• three cutaneous branches supply skin derived from maxillary prominence
• infraorbital n. (large terminal branch) passes through infraorbital foramen and supply skin on lat nose, upper lip and lower eyelid
• zygomaticofacial n. (small branch) emerges from zygomatic bone through zygomaticofacial foramen to supply skin over zygomatic prominence
• zygomaticotemporal n. emerges through zygomaticotemporal foramen and supplies skin over temporal region

Mandibular Nerve (V³)

• inferior division of trigeminal nerve
• three sensory branches supply skin derived from mandibular prominence, and motor fibres supply muscles of mastication (only division to carry motor fibres)
• buccal n. emerges deep to ramus of mandible to supply skin of cheek over buccinator, mucous membrane lining and post part of gingival surface
• auriculotemporal n. passes med to neck of mandible and n turns up, post to it head and ant to auricle, n crosses over root of zygomatic process, deep to superf temporal a., supplies parts of auricle, ext acoustic meatus, tmpanic mebrance and skin in temporal region
• inf alveolar n. (large terminal branch) enters mandibular canal through mandibular foramen, supplies branches to lower teeth, opposite mental foramen divides into incisive (incisor teeth) and mental (chin) branches
• lingual n. (small terminal branch) supplies general sensory fibres to ant 2/3 of tongue, floor o f mouth and mandibular gums

Motor Nerves

• CN VII (facial n.) supplies platysma, muscles of facial expression, auricular and scalp muscles
• sole motor supply to muscles of facial expression, taste sensation from ant ^2/3 of tongue, and secretomotor to salivary glands (except for parotid)
• emerges from skull through stylomastoid foramen (between mastoid and styloid processes), almost immediately enters parotid gland, runs superficially, gives off five terminal branches: temporal, zygomatic, buccal, mandibular and cervical
• emerge from sup, ant and inf margins of parotid gland and spread out like abducted digits

Arterial Supply

• two main arteries supply most of blood to face: facial and superior temporal aa.
• branches from supraorbital and supratrochlear supply skin of forehead

Facial Artery

• chief a. of face
• arises from ext carotid and winds it was to inf mandible just ant to masseter, usually grooving bone, lies superf here and pulsations can easily be felt
• crosses mandible, buccinator and maxilla, lies deep to zygomaticus major and levator labii superioris
• branches on face include submental, inferior labial, superior labial, and lat nasal

Superficial Temporal Artery

• smaller of two terminal branches of ext carotid a.
• begins within parotid gland, post to neck of mandible, ascends superf to post part of zygomatic process, enters temporal fossa and ends in scalp by dividing into frontal and parietal branches
• transverse facial a. arises from superf temporal a. before it emerges from parotid gland, crosses face superf to masseter, about fingerbreadth inf to zygomatic arch , supplies parotid gland, masseter and skin of face, anastomoses with branches of facial a.

Venous Drainage

• facial vein is major route of drainage from face

• formed by union of supraorbital and supratrochlear vv. at med angle of eye
• connected sup ophthalmic v. through supraorbital v. (near zygomatic process)
• connected to cavernous sinus by ophthalmic v.
• crosses superf to submandibular gland and is joined by anterior division of retromandibular v. to form common facial v., which ends by draining into internal jugular v.

Retromandibular Vein

• formed by union of superf temporal and maxillary vv., post to neck of mandible
• descends within parotid gland, superf to ext carotid a. but deep to facial n.
• divides into ant branch that unites with facial v. and post branch that joins posterior auricular v. to form external jugular v.

Lymph Drainage

• forehead and ant face  submandibular nodes
• lat face  parotid nodes
• central lower lip and chin  submental nodes

Muscles of Face

• embedded in superficial fascia
• most arise from bones of face and insert into skin, they don’t move bony structures
• orbit, nose and mouth are guarded by eyelids, nostrils and lips respectively

• facial muscles serve as sphincter, or dilators of the facial openings

• all develop from 2^nd pharyngeal arch and are supplied by facial n. (VII cranial)

Notes
Eye	orbicularis oculi	sphincter (narrows eye and encourages secretion of tears)	three parts: orbital (closing eyes tightly), palpebral (closing eyes lightly), lacrimal (pulls eye med)
Nose	nasalis	compression/dilation of nostril	compressor naris: rudimentary in human dilators of nose: flare the alar cartilages of nose
Mouth	orbicularis oris	sphincter	fibres derived from buccinator and or facial muscles
	dilator muscles		radiate out like spokes
	buccinator	presses cheeks against teeth	attached to alveolar processes and pterygomandibular raphe fibres mingle with orbicularis oris

Scalp

• covers vault of skull and extends sideways between right and left temporal lines, between eyebrows anteriorly and sup nuchal lines posteriorly

		Scalp
Boundaries		covers vault of skull lat: temporal lines ant: eyebrows post: sup nuchal line
Contents	Arteries	from int carotid (supraorbital, supratrochlear) from ext carotid (superf temporal, post auricular occipital)
	Veins	supratrochlear & supraorbital ( facial) superf temporal + maxillary ( retromandibular) post auricular + post retromandibular ( ext jugular) occipital ( suboccipital plexus  vertebral) emissary (communication with inside of skull)
	Nerves	trigeminal (supratrocheal, supraorbital, zygomatico-temporal, auriculo-temporal) C2 (greater & lesser occipital)
	Muscles	occipitofrontalis tempoparietalis
	lymph	scalp above parotid gland  parotid lymph nodes scalp above auricle  retroauricular lymph nodes back of scalp  occipital lymph nodes
Notes		trigeminal supply ant to line between ears and vertex, C2 supplies rest

Layers

• has five layers, of which first three are intimately bound toger: skin, connective tissue, aponeurosis epicranialis (scalp proper), loose areolar tissue, and pericranium
• mobile because of potential cleavage plane

Epicranial Aponeurosis

• strong membranous sheet that covers sup aspect of calvaria
• aponeurosis is membranous tendon of fleshly bellies of epicranial muscle (formed by occipitalis and frontalis muscles, each with two bellies: 2 frontal & 2 occipital)

• muscles are supplied by facial nerve (VII)

Applied Anatomy

• scalp richly supplied by blood  small lacerations may bleed profusely
• tension of epicranial aponeurosis (produced by occipitofrontalis) means that deep wounds dividing aponeurosis will gape
• infection of scalp may occasionally spread (via emissary vv.) to skull bones, infected blood in diploic vv. may travel via emissary vv. into venous sinuses and produced venous sinus thrombosis

Cranial Fossae

• cranial base has three levels called anterior, middle and posterior cranial fossae
• each fossa slightly inferior to one rostral to it

Anterior Cranial Fossa

• occupied by of frontal lobes of cerebral hemispheres
• formed mainly by frontal bone (ant boundary)

• most floor composed of convex orbital parts (bone roof of orbits)
• shows sinuous, shallow depression called convolution impressions or brain markings, possibly formed by the gyri of the brain

• crista galli is median process (resembling cock’s crest) that projects sup from ethmoid bone
• on both sides of crista galli is a narrow, cribriform plate, with numerous foramina for olfactory nn.
• lesser wings and jugum of sphenoid bone form posterior floor (boundary) of fossa

• lesser wings have sharp post spenoidal ridges that overhang ant middle fossa and project into ant part of lateral sulci
• each lesser wing ends med in ant clinoid process which gives attachment to tentorium cerebelli

Middle Cranial Fossa

• occupied by temporal poles and ~½ of inf surface of temporal lobe
• marked off from posterior fossa by dorsum sellae (med) and sup border of petrous part of temporal bone (lat), and from ant fossa by posterior edge of lesser wing of sphenoid
• saddle-like part of spenoid bone (between ant & post clinoid processes) known as sella turcica, composed of three parts:

• tuberculum sellae: ant, olive-shaped swelling
• hypophoseal fossa: mid, seat-like depression
• dorsum sellae: post, median rectangular projection

Posterior Cranial Fossa

• largest and deepest of fossae
• occupied by pons, cerebellum and medulla
• formed largely by inf and ant occipital bone, but sphenoid and temporal bones also contribute
• broad bony grooves formed by transverse sinuses lie between diverging folds of tentorium cerebelli (groove for right usually larger because sup sagittal sinus usually enter on right)
• foramen magnum located in centre of fossa

• rostral to foramen, basilar part of occipital bone rises to meet sphenoid bone, called clivus

• internal occipital crests is bony crest that lies post and sup to foramen magnum

• partly divides post cranial fossa into two cerebellar fossae that lodge cerebellar hemispheres
• end sup and post inirregular elevation called internal occipital protuberance

• vermis of cerebellum lies in vermian fossa, just post to foramen magnum

Foramina of skull

Foramen Ovale

1. Mandibular div. of trigeminal
2. Accessory meningeal A.
3. Lesser petrosal N.

Foramen spinosum

1. Middle meningeal A.
2. Meningeal branch of mandibular N.

Carotid canal

Int. carotid A. with venous and sympathetic plexuses

Palatovaginal canal

1. Pharyngeal branch of pterygopalatine ganglion
2. Minute pharyngeal branch from 3^rd part of maxillary artery

Pterygoid canal

Nerve of pterygoid canal

Sphenoidal emissary foramen

Emissary vein from cavernous sinus

Foramen lacerum

1. Int. carotid A.
2. Deep petrosal N.
3. Greater petrosal N.
4. Meningeal branches of ascending pharyngeal A.
5. Emissary vein from cavernous sinus.

2 and 3 join to form N. of pterygoid canal.

Foramen magnum

1. Apical ligament of dens
2. Membrana tectoris
3. Medulla oblongata
4. Meninges
5. Spinal roots of accessory N.
6. Vertebral A. with sympathetic plexus
7. Post. spinal A.
8. Ant. spinal A.

Hypoglossal canal

1. Hypoglossal N
2. Meningeal br. of ascending pharyngeal A.
3. Emissary vein from basilar plexus

Jugular foramen

1. Inf. petrosal sinus
2. Glossopharyngeal N.
3. Vagus N.
4. Accessory N.
5. Int. jugular V.
6. Sigmoid sinus

Condylar canal

Emissary vein from sigmoid sinus

Stylomastoid foramen

1. Facial N.
2. Stylomastoid br. of post. auricular A.

Cribriform plate of ethmoid

Olfactory N form nasal mucosa to olfactory bulb

Ant. ethmoidal canal

1. Ant. ethmoidal N.
2. Ant. ethmoidal vessels

Post. ethmoidal canal

Post. etmoidal vessels

Optic canal

1. Optic N.
2. Ophthalmic A.
3. Meninges

Superior orbital fissure

1. Terminal branches of ophthalmic N.
2. Ophthalmic V.
3. Occulomotor
4. Trochlear
5. Abducent

Foramen rotundum

Maxillary N.

Internal acoustic meatus

1. Facial N.
2. Vestibulocochlear N.
3. Nervus intermedius
4. Labyrinthine vessels

Facial canal

Facial N.

Mastoid foramen

1. Emissary V. from transverse sinus
2. Meningeal branch of occipital A.

Foramina of the skull

	Foramina	Contents
		Or	Nerves
Anterior	foramen cecum	nasal emissary v. (present in children and 1% of adults)
	foramina in cribiform plates		axons of olfactory cells
	ant & post ethmoidal foramina	vessels and nn. with same names
Middle	optic canals	ophthalmic aa.	CN II
	sup orbital fissures^*	ophthalmic vv.	CN V^1, III, IV, VI, SNS
	foramen rotundum^*		CV V^2 (maxillary n.)
	foramen ovale^*	accessory meningeal a.	CN V^3 (mandibular n.)
	foramen spinosum^*	mid meningeal vessels	meningeal branch of CN V^3
	foramen lacerum^*	int carotid a. accompanying sympathetic and venous plexuses
	hiatus of greater petrosal n.	petrosal branch of mid meningeal a	greater petrosal n.
Posterior	foramen magnum	vertebral, ant & post spinal aa. dural vv.	medulla and meninges spinal roots of CN XI
	jugular foramen	sup bulb of int jugular v., inf petrosal & sigmoid sinuses meningeal branches of asc pharyngeal and occipital aa.	CN IX, X, XI
	hypoglossal canal		CN XII
	condylar canal	emissary v.
	mastoid foramen	mastoid emissary v. meningeal branch of occipital a.

• ^* part of crescent of foramina

Cranial Meninges and CSF

• brain is enveloped by three membranes: dura mater, arachnoid mater and pia mater (arachnoid + pia = leptomeninges), collectively known as cranial meninges
• continuous with spinal meninges covering spinal cord
• cranial meninges and CSF provide support and protection for brain

Dura Mater

• outermost and toughest of cranial meninges
• consists of collagenous connective tissue
• dura mater loosely attached to calvaria, but tightly attached to base

• fractures of base more easily damage dura leading to leakage of CSF out of nose and ear

• two layered structure

• inner: meningeal
• outer: endosteal

• internal layer continuous with spinal dura at foramen magnum
• provides tubular sheaths for CNS as they pass through foramina in floors of cranial fossae; outside skull theyy fuse with epineurium, dural sheaths of cranial nerves extend approximately to cranial ganglia

• trigeminal ganglion surround by extension of cranial meninges, occupies trigeminal cave in trigeminal impression in petrous part of temporal bone
• dural sheath of optic nerve continuous with int meningeal layer of cranial dura and sclera of eye

Dural Septa or Reflections

• during development of brain, dura duplicated to form four inwardly projecting dural septa
• septa divide cranial cavity into three intercommunicating compartments, one subtentorial and two supratentorial

Falx Cerebri

• large, sickle shaped vertical partition in longitudinal fissure between hemispheres
• attached in median place to int surface of calvaria from frontal crest of frontal bone and crista galli of ethmoid bone ant, and int occipital protuberance post
• also attached to midline of tentorium cerebelli
• at sup border, its two layers separate to enclose sup sagittal sinus, free inf edge encloses inf sagittal sinus
• forms rigid partition between hemispheres and reduces side-to-side movement

Tentorium Cerebelli

• wide tent-shaped, arched fold of dura
• separates occipital lobes from cerebellum
• med attachment of falx cerebri holds tentorium cerebelli up
• attached ant-lat to sup petromastoid parts of temporal bones and ant & post clinoid processes
• attached post to occipital bone along grooves for transverse sinuses, which it encloses
• U-shaped ant border is free, between it and dorsum sellae is opening called tentorial notch, which surrounds midbrain

Falx Cerebelli

• small, sickle-shaped median dural fold in post post cranial fossa
• extends almost vertically, inf to inf tentorium cerebelli
• free-edge projected slightly between cerebellar hemispheres
• occipital sinuses contained in fixed edge

Diaphragma Sellae

• small, circular, horizontal sheet of dura formsroof for hypophyseal fossa
• formed by dura surrounding pituitary gland and encircling its stalk

Arteries

• many meningeal aa. in periosteum supply most blood to periosteum, not meninges!
• only very fine branches of are distributed to dura
• middle meningeal a. is largest of meningeal aa., branch of maxillary a., embedded in dura, clinically imp because it can be torn when skull is fractured

• enters cranial cavity through foramen spinosum, runs lat along floor of the middle cranial fossa, turns sup-ant on greater wing of sphenoid, where it divides into ant and post branches
• ant branch runs sup to pterion and curves post to ascend towards vertex of skull, often found inbony tunnel in region of pterion
• post branch runs post in groove in squamous part of temporal bone, n ramifies all over post skull

• all meningeal aa. accompanied by veins, lie between aa. and bones

Nerve Supply

• rich sensory supply largely through three divisions of trigeminal n.

Arachnoid Mater

• delicate, transparent membrane, composed of weblike tissue
• forms intermediate covering of brain and separated from dura by film of fluid in potential subdural space
• it does not closely investment of brain, but passes over sulci and fissures
• separated from pia by subarachnoid space
• numerous trabeculae pass from arachnoid to pia, givingweblike structure

Pia Mater

• very thin, highly vascularised, loose connective issue membrane that adheres closely to surface of brain
• dips into all sulci and fissures and carries blood vessels with it
• cerebral veins run on pia within subarachnoid space
• when branches of cerebral vessels penetrate brain, pia follows for a short distance, forming sleeve of pia, refore perivascular spaces are continuous with subarachnoid space

Venous Sinuses of Dura Mater

• sinuses are venous channels located between dura and int endosteal lining of cranium
• drain all blood from brain

Superior Sagittal Sinus

• lies in superior border of falx cerebri
• usually ends by becoming right transverse sinus
• dilation at termination known as confluence of sinuses as five sinuses communicate with it

Inferior Sagittal Sinus

• lies in inf border of falx cerebri
• much smaller than sup sagittal sinus
• ends by joining great cerebral v. to form straight sinus

Straight Sinus

• runs along the line of attachment of falx cerebri to tentorium cerebelli
• ends by joining one of transverse sinuses, usually left

Transverse Sinus

• pass lat from confluence of sinuses in attached border of tentorium cerebelli
• leave tentorium and become sigmoid sinuses

Sigmoid Sinuses

• follow S-shaped course in post cranial fossa, forming deep groove in the temporal and occipital bones, turn ant and enter sup bulbs of int jugular vv.

Occipital Sinus

• lies in attached edge of falx cerebelli

Superior and iferior Petrosal Sinuses

• they drain the cavernous sinus into the transversesinus and int j v respectively

Cavernous Sinuses

• large venous sinuses, 2 cm x 1 cm, capacity: 1.5 ml
• located on eir side of pituitary in sella turcica
• runs from apex of orbit to apex of petrous temporal bone
• contain many blood channels formed by numerous trabeculae

Receives blood from:

• sup and inf ophthalmic vv. (orbit)
• superf mid cerebral v. (brain)
• sphenoparietal sinus (skull)
• intercavernous sinuses (cavernous sinus of or side)

Drains blood into

• sup and inf petrosal sinuses
• pterygoid venous plexus

Relations

• ant: apex of orbit
• post: brain stem (junction of peduncle with pons)
• med: body of sphenoid bone and pituitary fossa
• lat: temporal lobe
• sup: int carotid a., uncus of temporal lobe
• inf: greater wing of sphenoid

Immediate relations

• lat: oculomotor, trochlear, ophthalmic, and maxillary nn.
• inside sinus but outside blood: int carotid a., abducens n.

Mouth

• oral cavity is divided into vestibule and mouth proper
• vestibule lies within cheek and lips, but outside gums and teeth
• mouth cavity communicates post with pharynx through oropharyngeal isthmus (isthmus of fauces)

• bounded by soft palate above, tongue below and palatoglossal arches on each side

• palate (hard and soft) forms roof of mouth

Lips

• covered ext by skin, int by mucous membrane
• contains part of orbicularis oris
• attach to gum by frenulum
• mucous labial glands moisten lip
• meet at angles (labial commisures) of mouth

Cheeks

• directly continuous with lips and have same general structure
• buccinator forms muscle layer

Tongue

General Features

• three parts: root (or base, post ^1/3, post-sulcal, pharyngeal part); body (or ant ^2/3, pre-sulcal, oral part); and tip
• two surfaces: upper (dorsum) and lower (ventrum)
• upper surface divided into two parts by V shaped sulcus terminalis: ant ^2/3 oral part, post ^1/3 pharyngeal part

• foramen caecum located at apex of V
• mucous membrane of the upper surface of the oral part is rough due to presence of numerous lingual papillae
• mucous membrane of the lower surface of the oral part is smooth , devoid of papillae, and shows visible deep lingual v. either side of frenulum
• post ^1/3 is devoid of papillae but has a nodular irregular surface caused by the underlying lymph nodules called lingual tonsil.

• the interval between the post ^1/3of the tongue and the epiglottis is part of oropharynx and shows: median and lateral glossoeppiglottic folds, and vallecullae (a small depression detween the two folds)

Lingual Musculature

Muscles		Main actio	Nerve supply
Extrinsic	genioglossus	protrusion	CN XII
	hyoglossus	depression
	styloglossus	retraction
	palatoglossus	elevation	Pharyngeal plexus
Intrinsic	sup longitudinal muscle	they change the shape of the tongue	CN XII
	inf longitudinal muscle
	transverse muscle
	vertical muscle

Nerve Supply

		Ant ^2/3	Post^1/3
Sensory	General	lingual (CN V)	glossopharyngeal
	Special	chorda tympani (CN VII)
Motor		hypoglossal (except for palatoglossus, supplied by CN X)

Arterial Supply

• major: lingual a.
• also tonsillar and asc palatine branches of facial a.

Venous Drainage

• all veins on one side unite to form lingual v., which drains into int jugular or facial v.

Lymphatics

• tip: submental
• ant 2/3: submandibular (central cross to opposite side as well)
• post 1/3: deep cervical

Applied Anatomy

• glossitis usually accompanies stomatitis

• in acute glossitis, oedema and swelling of tongue are marked (facilitated by loose c.t. and plenty of lymphatics)

• in some anaemias and vitamin deficiencies tongue becomes bald, due to atrophy of filiform papillae
• lesion of hypoglossal n. results in paralysis of affected side and hemiatrophy, when patient tries to stick out tongue, deviates to paralysed side
• in unconscious patient, post tongue may fall back and cause laryngeal obstruction
• carcinoma of post tongue has poor prognosis due to bilateral lymphatic spread

Palate

Hard Palate

• skeleton: palatine process of maxilla, horizontal plate of palatine
• alveolar margin: teeth and gums
• post margin: soft palate
• oral surface: stratified squamous keratinised epith, mucosa adheres to bone, palatine raphe, transverse palatine folds, mucosal glands prominent

Soft Palate

• base: attached to post hard palate
• free post border presents uvula in midline
• palatoglossal folds extend inf and ant; and palatopharyngeal folds extend inf and post from the under surface of the soft palate
• has oral (lower) and pharyngeal (upper) surfaces

Structure

• oral mucosa on oral surface and adjoining pharyngeal surface; rest covered by respiratory mucosa
• core is palatine aponeurosis with levator palati on upper surface and palatopharyngeus and palatoglossus on lower surface

Muscles

• tensor and levator palati
• musculus uvulae
• palatoglossus
• palatopharyngeus

Blood Supply

• branches of maxillary a. (greater and lesser palatine aa.)
• veins drain into pterygoid venous plexus

Lymphatics

• drain into submandibular, retropharyngeal, and deep cervical nodes

Nerve Supply

• sensory: greater and lesser palatine nn., nasopalatine n.
• motor: pharyngeal plexus, except tensor palati supplied by mandibular n.

Submandibular Region

• lies between body of mandible and hyoid bone

• superficial part includes submental and digastric triangles
• deeper parts include root of tongue and floor of mouth

Structures

• muscles: digastric, stylohyoid, mylohyoid, hyoglossus
• submandibular gland

• mixture of serous and mucous acini
• two parts: superficial and deep

• superficial: in digastric triangle, reaching upward under cover of mandible, separated post from parotid gland by stylomandibular lig
• deep: extends forwards in interval between mylohyoid and hyoglossus, post end continuous with superf part of gland, while ant end reaches as far as sublingual gland

• coverings: inner ct capsule and outer fibrous capsule (derived from deep cervical fascia)
• submandibular duct: runs from ant deep submandibular gland, forward between mylohyoid and hyglossus
• blood supply: branches of lingual and facial, veins follow aa.
• nerve supply: derived from submandibular ganglion (receives parasympathetic fibres from chorda tympani, lingual and sympathetic trunk)

• applied submandibular salivary gland

• common site of calculus formation
• presence of tense swelling below body of mandible, greatest before and during meal and reduced in size or absent between meals

Parotid Glands

• largest of salivary glands (branched serous acini)
• very irregular shape because it’s wedged in among number of structures
• covered by a capsule and a dense fibrous tissue sheath (parotid fascia) formed by deep cervical fascia
• divided into two (superficial and deep) parts by facial n.:

Position and Extent

• lies in fossa post to ramus of mandible
• extends from external acoustic meatus to upper part of carotid triangle
• med, extends to styloid process and around neck of mandible
• post, overlaps sternocleidomastoid and extends ant over masseter
• portion of facial part often detached and called accessory parotid gland
• wedge-shaped (base above, apex behind angle of mandible)
• sup: extends upward behind TM joint into post mandibular fossa, called glenoid process
• ant: extends forwards superf to masseter, called facial process

Parotid Duct

• 5 cm long, 5mm wide
• passes horizontally from ant edge, turns med at ant masseter and pierces buccinator, and enters oral cavity opposite crown of 2^nd maxillary molar tooth

Structures within the Gland

• facial n (superf)
• retromandibular v
• external carotid a. (deep)

Nerve and blood Supply

• supplied by branches of external carotid a., drains by tributaries of retromandibular v.
• secretomotor (parasympathetic): from glossopharyngeal n. (IX), via otic ganglion
• sensory: branches from greater auricular and auriculo-temporal nn.

Applied Anatomy

Nose and Nasal Cavity

• sup part of respiratory tract and contains peripheral organ of smell
• divided into right and left nasal cavities by nasal septum
• its mucosa is divisible into olfactory and respiratory areas
• functions include

• respiration
• olfaction
• filtration of dust
• humidification of inspired
• receives secretion form paranasal sinuses and nasolacrimal ducts

Skeleton of External Nose

• immovable bridge of nose (sup bony part of nose) consists of nasal bones, frontal processes of maxillae and nasal part of frontal bone

Nasal Septum

• bony part of septum usually located in med plane, until 7 years of age when it deviates slightly to one side (more frequently right)
• nasal septum has three main components

• perpendicular plate of ethmoid bone: (forms sup part, very thin, desc from cribriform plate)
• vomer: (forms post-inf part, thin, flat bone)
• septal cartilage

• movable cartilaginous part of nose consits of five main cartilages andfew smaller ones

• composed of hyaline cartilage
• connected with one anor and nasal bones by continuity of perichondrium and periosteum
• U-shaped alar nasal cartilages are free and movable, can dilate and constrict nares

Nasal Cavities

• nasal cavity opens anteriorly through nostrils or ant nares
• open posteriorly into nasopharynx through choanae (post nasal aperture)
• mucosa lines entire nasal cavity, except vestibule
• entrance to vestibule of nose is lined with skin containing hairs called vibrissae
• nasal mucosa is tightly bound to periosteum and perichondrium of supporting structures

• continuous with lining of all chambers with which nasal cavities communicate
• inf ^2/3 called respiratory area, and sup ^1/3 called olfactory area

Walls

• floor: palatine process of maxilla, horizontal plate of palatine bone
• roof: nasal bone, frontal bone, cribriform plate of ethmoidal bone and body of sphenoidal bone, communication with cranial cavity through cribriform plate
• septum: formed by vomer, perpendicular plate of ethmoid, septal cartilage, fibrofatty tissue of mobile septum
• lateral wall: skeletal framework : nasal bone; frontal process of maxilla, lacrimal,; ethmoid labyrinth with sup and mid conchae, inf concha, perpendicular plate of palatine bone, med pterygoid plate

• uneven due to three shelf-like projections called superior, middle and inferior conchae
• sphenoethmoidal recess lies above sup concha; other spaces are sup, middle and inf meatuses lie below the corresponding conchae
• hiatus semilunaris is a curved cleft (window) in the middle meatus, lies between bulla ethmoidalis superiorly and uncinate process of ethmoid bone inferiorly
• infundibulum: is a space within the middle meatus that lies lat to the hiatus it receives the frontonasal duct (draining the frontal and ant ethmoid sinuses)
• maxillary sinus opens in the middle meatus, below the bulla and above the inferior edge of the hiatus
• post ethmoidal sinus opens in sup meatus; nasolacrimal ducts into inf meatus
• sphenoidal sinus opens in sphenoethmoidal recess

Linings

• vestibule: lined by skin with vibrissae
• roof, adjoining septum and alt wall – olfactory mucosa
• rest of nasal cavity – respiratory mucosa
• nasal mucosa continuous with that in paranasal air sinuses

Nerve Supply

• CN I: olfactory area in the upper part of nasal cavity
• CN V¹: ethmoidal branches of nasocilliary n
• CN V²: branches to the walls of the nasal cavity

Arterial Supply

• derived mainly from branches of:
• maxillary a.(sphenopalatine, greater palatine)
• ophthalmic a. (ethmoidal a.)
• facial a. (sup labial, ascendimg palatine, lateral nasal)

Venous drainage

• rich venous plexuses in the nasal mucosa are drained by pterygoid plexus, facial v and ophthalmic veins

Lymphatics

• drain into submandibular, retropharyngeal, and upper deep cervical nodes

Paranasal Air Sinuses

• definition: they are air filled cavities within the frontal, ethmoidal, sphenoidal and maxillary bones, are lined with the respiratory epithelium, and communicate with the nasal cavity through small apertures
• rudimentary at birth; grow at 6-7 years to attain maximum size at puberty; in adult, they vary considerably in size in different people

Mucosa

• respiratory type, but thin, less vascular and loosely attached to periosteum

Frontal Sinus

• situated between inner and outer tables of frontal bones beneath med ^1/3 of superciliary arch
• opens into mid meatus via infundibulum

Maxillary Sinus

• is the largest of paranasal sinuses; situated in maxilla
• pyramidal in shape, apex facing zygoma, and base towards the nasal cavity
• opens in mid meatus, well above its floor

Ethmoidal Sinuses

• numerous cavities called cells, within ethmoidal labyrinth
• are grouped into ant, mid and post groups
• all contained in labyrinthine (lateral) part of ethmoidal bone
• ant ethmoid sinus opens with frontal sinus in the middle meatus via infundibulum
• mid ethmoid sinus underlies bulla ethmoidalis; opens on the bulla into the middle meatus
• post ethmoid opens into sup meatus

Sphenoidal Sinus

• situated in body of sphenoid bone; divided by a septum
• related to the pituitary gland, cavernous sinus, and internal carotid a.
• opens into sphenoethmoidal recess

Nerve Supply of Paranasal Sinuses

• branches of CN V¹
• branches of CN V²

Blood Supply of Paranasal Sinuses

• branches of maxillary a.
• branches of ophthalmic a.
• branches of facial artery.

Lymphatics of Paranasal Sinuses

• submandibular group (frontal, ant and middle ethmoidal and maxillary sinuses)
• retropharyngeal group (post ethmoidal and sphenoidal sinuses)

Orbit and Contents

• bones that form orbit are lined with periosteum, called periorbita or orbital periosteum

• at optic canal and sup orbital fissure, periorbita becomes continuous with periosteum lining interior of skull
• also continuous over orbital margins and through inf orbital fissure with periosteum covering external surface of skull
• forms funnel-shaped fascial sheath that encloses orbital contents
• may be easily detached especially from roof and med wall

Margins of the orbit

• med: frontal and maxillary
• sup: frontal
• lat: zygomatic and frontal
• inf: zygomatic and maxillary

Walls of the orbit

• med: maxilla, lacrimal, ethmoid, sphenoid. Features: nasolacrimal canal, ant & post
• ethmoidal foramen
• sup(roof): frontal (orbital plate), sphenoid (lesser wing). Features: lacrimal fossa, optic
• foramen, trochlear fossa
• lat: sphenoid (greater wing), zygomatic (orbital surface). Feature: zygomatic
• canal
• inf (floor): maxilla, zygomatic, palatine. Features: infraorbital canal and groove

Superior Orbital Fissure

• separates lat wall from sup wall (roof)
• lies between lesser and greater wings of sphenoid
• connects orbit with mid cranial fossa
• transmits CN III, IV, V¹, ophthalmic vv.

Inferior Orbital Fissure

• separates floor from lat wall
• lies between greater wing, maxilla and zygomatic bone
• connects orbits with pterygolpalatine and infratemporal fossae
• transmits maxillary n., zygomatic n., infraorbital vessels

Contents

Muscles

	Origin	Insertion	Innervation	Action
Levator palpebrae superioris	roof of orbit, ant to optic canal	skin of upper eyelid	CN III	elevates upper lid
Superior rectus	common tendinous ring	just post to sclerocorneal junction		elevate, adduct
Inferior rectus				depress, adduct
Medial rectus				adducts eye
Lateral rectus			CN VI	abducts eye
Superior oblique	body of sphenoid	runs through trochlea, post-sup lat orbit	CN IV	depress, abduct
Inferior oblique	maxilla in floor of orbit	post-inf lat orbit	CN III	elevate, abduct

Fascial Sheath of eyeball (bulbar fascia or Tenon’s fascia):

• thin cuplike sheath surrounds eyeball, except for corneal part
• separates it from fat and or contents in orbit
• attached posteriorly to sclera close to optic nerve and anteriorly just post to cornea
• tendon of muscles pierce sheath on their way to their attachments
• blends with fascial sheaths of ocular muscles
• fuses with dural sheath of optic nerve
• potential space between eyeball and fascial sheath allows eyeball to move freely
• triangular expansions (called check ligaments) from sheaths of med and lat rectus muscles are attached to lacrimal and zygomatic bones respectively
• thickening of inf part of the fascial sheath of eye called suspensory ligament of eyeball

• suspen lig is attached to ant parts of medal and lateral walls of orbit
• suspen lig supports eyeball with its hammock-like shape

Nerves of Orbit

• CN II, III, IV, V¹, VI
• ciliary ganglion

Blood Vessels

• orbital contents supplied by ophthalmic a.

• infraorbital a. also contributes some blood to this region

• venous drainage is through ophthalmic vv., sup & inf

Ophthalmic Artery

• arise from int carotid a. as it emerges from cavernous sinus
• pass through optic foramen within dural sheath of optic nerve and runs ant close to sup-med wall of orbit
• gives off branches to structures in orbit and to ethmoid bone

Central Artery of Retina

• one of smallest but most important branches of ophthalmic a.
• arises inf to optic n.
• runs within dural sheath of optic nerve until it approaches eyeball, n pierces optic nerve and runs within it to emerge through optic disc, spreads over int surface of retina
• twigs of artery anastomose with ciliary a. but terminal branches are essentially end aa.

Ciliary Arteries

• ciliary aa. supply sclera, choroid, ciliary body and iris
• two long post ciliary aa. piece sclera and supply ciliary body and iris
• several short post ciliary aa. pierce sclera and supply choroids
• ant ciliary aa are branches from muscular arteries. They supply conjunctiva and iris

Lacrimal Artery

• supplies lacrimal gland, conjunctiva and eyelids

Temporal Region

Temporal Fossa

• oval in shape on the lat aspect of the skull

• bounded sup and post by temporal lines
• inf, it communicates with infratemporal fossa
• roofed by temporal fascia
• occupied by temporalis muscle

Infratemporal Fossa

• irregularly-shaped space inf and deep to zygomatic arch and post to maxilla
• communicates with temporal fossa through interval between arch and skull and temporal msucles and deep temporal nerves and vessels pass through it

Boundaries

• ant: post surface of maxilla
• post: styloid process
• sup: infratemporal surface of greater wing of sphenoid
• inf: continuous with submandibular region
• lat: ramus of mandibular
• med: lat pterygoid plate

Contents

• muscles: lat and med pterygoid, lower part of temporalis
• nerves: mandibular, otic ganglion, chorda tympani
• vessels: maxillary a. and v, pterygoid venous plexus

Maxillary a.

• larger of two terminal branches of ext carotid
• arises post to neck of mandible, passes forwards (deep to neck), and transverses infratemporal fossa, passes superf to lat pterygoid and then disappears into pterygopalatine fossa

Part (divided by lat pterygoid)	Course	Branches
First	passes horizontally forwards between neck of mandible and lower border of pterygoid	deep auricular ant tympanic mid meningeal accessory meningeal inf alveolar
Second	runs obliquely forward and upwards superf to inf head of lat pterygoid	to muscles of this region
Third	runs between sup and inf heads of lat pterygoid, then through pteryggomaxillary fissure into pterygomandibular fossa	post sup alveolar infraorbital desc. palantine pharyngeal sphenopalatine

Pterygoid Venous Plexus

• is associated with pterygoid muscles
• connected to facial v. through deep facial vv.
• connected to cavernous sinus through vv. passing through foramen ovale and lacerum

Mandibular Nerve

• branches into all nerves in infratemporal region (except for chorda tympani, branch of facial)
• descends through foramen ovale into infratemporal fossa, divides into sensory and motor fibres
• supply four muscles of mastication, but not buccinator

Part	Type	Branch
Main trunk	Motor (3)	med pterygoid m
		tensor tympani m
		tensor palati m
	Sensory (1)	meningeal
Ant division	Motor (3)	massteric n to masseter m
		deep temporal nn. to temporalis
		n. to lat pterygoid
	Sensory (1)	buccal	usually runs between two heads of lat pterygoid, desc through deep temporalis, supplies skin and mucous membrane of cheek
Post division	Motor (1)	n. to mylohyoid and ant digastric
	Sensory (3)	auriculotemporal	encircles med meningeal a., breaks up into many branches, largest passes post, med to neck of mandible and supplies auricle and temporal region, also sends articular fibres to temperomandibular joint
		lingual	lies ant to inf alveolar n., sensory to tongue, floor of mouth and gingivae, enters mouth between med pterygoid muscle and ramus of mandible, passes ant under oral mucosa, just inf to 3^rd molar tooth chorda tympani branch of facial n. travels with it
		inf alveolar	enters mandibular foramen, passes through mandibular canal (where it sends nn. to teeth) and appears on face as mental n., supplies skin and mucous membrane of lower lip, skin of chin

Otic Ganglion

• is parasympathetic ganglion
• is located in infratemporal fossa, just inf to foramen ovale, med to mandibular n. and post to med pterygoid muscle
• secretory to parotid gland

Temporomandibular Joint

• type: synovial joint; subtype: modified hinge or condylar variety
• articular surface involved are:

• head or condyle of mandible (inf)
• articular tubercle and mandibular fossa of squamous temporal bone (sup)

• articular disk separates joint cavity into sup and inf compartments

• fused with articular capsule surround joint and is bound sup to limits of temporal articular surface int to neck of mandible
• articular disc is more firmly attached to mandible than to the temporal bone

• loose articular capsule attached to margins of area on temporal bone and neck of mandible

• thickened lat to form lat (temporomandibular) ligament

• base attached to zygomatic process, apex to lat side of neck of mandible

• stylomandibular and sphenomandibular also help to support the T-M joint

Movement	Muscles
depression	hyoid muscles, gravity
elevation	temporalis, masseter, med pterygoid
protrusion	lat and med pterygoid, masseter (deep fibres)
retraction	post temporalis
side-to-side	med and lat pterygoid, masseter

Muscle	Origin	Insertion
Temporalis	temporal fascia	coronoid process, ant ramus
Masseter	zygomatic arch	lat ramus
Lat pterygoid	sup: infratemporal crest inf: lat lat pterygoid plate	neck of mandible, articular disk
Med pterygoid	superf: maxillary tuberosity deep: med lat pterygoid plate	med ramus

Things to Know

The Cranium

1	To what does the term "skull" refer?	The skeleton of the head, including the teeth, hyoid bone and ear ossicles.
2	What is the skull minus the mandible called?	The cranium.
3	What is the term for the brain case?	The cranium - so some confusion can occur with the word ‘cranium’.
4	What is the rest of the skull called?	The skeleton of the face.
5	How many bones are there in the cranium (brain case)?	Eight.
6	Which also contribute to the facial skeleton?	Sphenoid (by pterygoid process) and ethmoid.
7	What are the junctions between the calvarial bones called?	Sutures.
8	Are they all similar? Which one in particular is different?	No. The parietotemporal (or squamosal) suture, which does not interlock.
9	Which bone(s) contribute to the anterior wall of the posterior cranial fossa?	Temporals and occipital.
10	Which bone(s) contribute to the anterior wall of the middle cranial fossa?	Sphenoid.
11	Which bone(s) contribute to the anterior wall of the anterior cranial fossa?	Frontal.
12	Which bone(s) contribute to the floor of the anterior cranial fossa?	Frontal, ethmoid and sphenoid.
13	Which bone(s) contribute to the floor of the middle cranial fossa?	Sphenoid and temporal (both petrous and squamous parts).
14	Which bone(s) contribute to the floor of the posterior cranial fossa?	Occipital.
15	Does the parietal bone contribute to the lateral wall of the posterior cranial fossa?	Not really. Although there is a deep groove for the junction of the transverse and sigmoid sinuses, because they lie in the attached edge of the tentorium the parietal is really excluded from facing into the posterior cranial fossa.
16	What is the pterion?	The REGION where the sphenoid and parietal bones meet in the temporal region.
17	What is the asterion?	The junction of the parietal, occipital and temporal bones just above and behind the mastoid.
18	Where is the bregma?	At the junction of the sagittal and coronal sutures.
19	Where is the lambda?	At the junction of the sagittal and parieto-occipital (lambdoid) sutures.
20	What muscles arise from the calvaria?	The occipitalis and temporalis muscles.
21	Which major groups of muscles insert into the cranial base?	The back muscles - we usually refer to them as the muscles of the back of the neck.
22	What is the diplöe?	The trabecular or cancellous bone forming the middle layer of the calvarial bones.
23	Which is the thicker, the inner table or the outer table?	Outer.
24	Name the main vessel supplying the bones of the calvaria.	The middle meningeal artery.
25	Where does it lie before reaching the bones?	In the outer layers of the dura.
26	Which bone in the skull does it traverse to enter the cranium? What is the opening it traverses?	The sphenoid, through the foramen spinosum.
27	From what artery does it directly arise? What vessel gives rise to that artery?	The maxillary, a branch of the external carotid.
28	Where do the veins accompanying the artery of the calvaria lie? Where do they terminate?	They lie in the dura, accompanying the meningeal arteries and end in the pterygoid plexus immediately outside the foramen spinosum.
29	About how thick is the dura mater?	½ - 1 mm.
30	What type of tissue is the dura?	Dense, regularly arranged fibrous connective tissue = aponeurotic tissue.
31	What two main roles does the dura service in the cranium?	As covering of the central nervous system and as periosteum.
32	Which of these roles is not served by the spinal dura?	The periosteal one, as spinal dura is separated from bone by extra-dural fat and veins.
33	What is the generic term for the venous blood spaces located in the dura?	The dural venous sinuses.
34	Name the venous channel in the attached border of the falx cerebri.	The superior sagittal sinus.
35	Name the venous channel in the attached border of the tentorium cerebelli.	The transverse (or lateral) sinus.
36	What is the name of the intradural space containing the carotid siphon (internal carotid artery)?	The cavernous sinus.
37	Name four other structures found in, or in the walls of, that space.	III, IV, V and VI nerves.
38	What venous channels drain the cavernous sinus?	The superior and inferior petrosal sinuses.
39	What venous channels drain into the cavernous sinus?	The ophthalmic veins, the middle superficial cerebral vein (and the sphenoparietal sinus).
40	How is the pituitary gland related to the cavernous sinuses?	Its lateral poles lie against the medial walls of the left and right cavernous sinuses.
41	What is the tentorium cerebelli?	The low, tent-like dural partition roofing over the posterior cranial fossa.
42	What is the falx cerebri?	The roughly sickle-shaped dural partition separating the two cerebral hemispheres above the corpus callosum.
43	What is the diaphragma sellae?	The dural covering of the pituitary fossa. A small opening in its centre allows the infundibulum to reach the gland.
44	Is there cerebrospinal fluid directly about the pituitary gland?	No, below the diaphragma sellae the CSF space is obliterated.
45	What direction does the hypophyseal stalk (infundibulum) run as it passes from the hypothalamus to the pituitary?	It runs downwards and forwards to the gland.
46	Is the arachnoid mater bound to the dura mater?	No. A smooth walled POTENTIAL space separates the two layers.
47	Is the arachnoid mater connected to the pia mater?	Yes, by the fine arachnoid processes crossing the subarachnoid space.
48	What is the volume of cerebrospinal fluid?	100 - 150 ml. Production about 500 ml/day.
49	About what distance separates pia and arachnoid?	2 - 3 mm.
50	Would you like to have more questions on the cranium?

The Scalp

1	What is the scalp?	It is the investment of the calvaria.
2	What particular characteristic distinguishes it from the immediately adjacent investing layers?	It has dense fibrous loculated subcutaneous tissue similar to that of the heel.
3	Define its anterior limit.	The eyebrows.
4	Define its posterior limit.	The superior muchal lines.
5	Where and how does it end at the sides of the head?	Along the zygomatic arch and just above the ears, where the much thinned galea blends with the periosteum.
6	Does it have distinctive regions?	Yes. Hair bearing and "non-hair" bearing; (the scalp and forehead of lay terminology).
7	What distinguishes such regions?	The presence of terminal hair or its absence.
8	Is that distinguishing feature found elsewhere in the body?	Yes. Axillary and pubic hair and the beard and eyelashes and eyebrows are all terminal hair as in the hair on the nape of the neck.
9	How thick is the scalp?	5 mm
10	Is it more or less uniformly thick?	It is uniformly thick and of essentially similar thickness in men and women.
11	How thick is the epidermis of the scalp? Is that thickness about average for epidermis?	100  m. Yes, that is average for the body.
12	How thick is the subcutaneous layer of the scalp? How does that compare with the average thickness throughout the body?	1.5 mm. Yes, that is thickness over most of the body.
13	Mention THREE distinctive features of the scalp (or of major parts of the scalp).	A Terminal Hair B Loculated subcutaneous tissue C Muscle superficial to the investing fascia
14	With what other parts of the body does it share feature A?	Face (in males), Axilla, Pubic and perianal areas, eye brows and eyelids.
15	With what other parts of the body does it share feature B?	The palms of the hands and soles of the feet.
16	With what other parts of the body does it share feature C?	The face, front of neck and upper chest. (The Dartos muscle in the scrotum is smooth muscle).
17	What are the dimensions of Frontalis approximately?	5 cm x 5 cm
18	From what does Frontalis arise? In to what does it insert?	The Galea aponeurotica; the skin of the eyebrows.
19	How big is Occipitalis in comparison to Frontalis?	Much smaller.
20	Does occipitalis abut the midline on each side?	No.
21	What are the auricular muscles?	Three superficial muscle slips running from the galea to the cartilage of the external ear near the cartilaginous external auditory meatus.
22	What is the Temporoparietalis muscle?	A fairly extensive sheet of muscle in the upper temporal region running from the ear upwards and forwards to the galea.
23	What is the name given to the Frontalis, Occipitalis, Temporoparietalis and galea aponeurotica together?	Epicranins muscle.
24	At which layer does the scalp move on the cranium?	At the layer of loose connective tissue between galea and periosteum (layer 4).
25	Where is the galea aponeurotica firmly attached to bone?	At the nuchal line (and, because it is much thinner, less firmly to the zygomatic arches).
26	What layers and structures separate the epidermis in the temporal region from the parietal and sphenoid bones?	Dermis, thinned galea, rather denser layer 4 (loose connective tissue), the temporalis fascia (representing a true investing fascia), the temporalis muscle and periosteum.
27	What vessels supply the scalp?	The supraorbital (medial and lateral branches). superficial temporal and occipital (assisted by the supratrochlear and posterior auricular).
28	Which of them come from the internal carotid artery? Are they direct branches of the internal carotid?	A supraorbitals and supratrochlear. No, they are branches of the ophthalmic a.
29	Which of them come from the external carotid artery? Are they direct branches of the external carotid?	The superficial temporal, occipital (and posterior auricular) are direct branches of the external carotid.
30	How much of the scalp is supplied by branches of the ophthalmic artery?	Just the forehead region. (The corresponding nerves (the supraorbital) supply right back to the vertex).
31	Which arteries anastomose across the sagittal suture?	The superficial temporals (thereby limiting the territory of the supraorbital arteries).
32	What veins drain the scalp?	Veins running with and having the same names as the arteries.
33	Which drain to the internal jugular vein? How?	The superficial temporals (thereby limiting the territory of the supraorbital arteries).
34	Which drain into the external jugular vein?	The occipital, posterior auricular and superficial temporal.
35	What nerves supply the scalp?	Cranial nerve V and cervical nerve 2.
36	What parts are supplied by cervical nerves?	The occipital region up to the vertex.
37	What parts are supplied by cranial nerves? Which cranial nerve?	The forehead back to the vertex and the temporal regions. Cranial nerve V, the trigeminal.
38	Which major division of the 5th cranial nerve supplies skin of the temporal region?	The mandibular division mainly (with a small contribution from the maxillary division anteriorly).
39	How are the muscles of the scalp innervated?	By the VIIth cranial nerve (facial nerve).
40	Are there lymphatics in the scalp?	Yes.
41	Where are lymph nodes found close to the scalp? What are the names of the various groups?	Around its lower limits, laterally and posteriorly. Preauricular, mastoid and occipital groups.
42	Haemorrhage from the veins piercing the cranial vault (from, for instance, moulding of the skull during birth) is limited to the extent of a single cranial bone. Why?	Because the periosteum is bound down tightly at the sutures and this type of bleeding occurs between the periosteum and the particular bone.
43	Gashes to the scalp bleed freely. Why? How would you control the bleeding?	Because the arteries are large and are tethered in the dense connective tissue of the scalp. Moderate pressure where the arteries enter the scalp.
44	Infections of sebaceous glands in the scalp are very painful. Why?	Because the pus is unable to spread far in the subcutaneous tissue and pressure builds up.
45	Cuts in scalp in a coronal direction gape; those in a sagittal direction don’t. Why?	Because the tension in the galea is from front to back because of the way the muscles are arranged.
46	Is the scalp well nourished?	Extremely well.
47	Do the bald areas of scalp contain hair follicles?; sebaceous glands? sweat glands?	Yes. Yes. Yes.
48	Is there hair on the forehead? If so, what kind?	Yes. Normal fine body hair.
49	Are eyebrow hairs different from head hair?	No. Both are terminal hair.
50	Do you think you have learned enough about the scalp?

The Face

1	What is the posterior limit of the face?	The coronal plane immediately behind the rami of the mandible and in front of the vertebral column (plane C) and in the upper 3 cm the plane through the anterior surface of the sphenoid (plane B).
2	What is the upper limit of the face? in anatomy? in lay terms?	The eyebrows. The hairline.
3	What is the lower limit of the face?	The floor of the mouth.
4	Name the reference blocks comprising the face.	Orbital, maxillary, dental; upper nasal, lower nasal, buccal, pharyngeal and pterygoid.
5	Name the three principal areas of contact between the face and the cranium.	The frontomaxillary sutures; the frontozygomtic sutures; the pterygopalatine sutures (where, in effect, the body of the maxilla is supported from behind by the pterygoid process).
6	What parts of the face have particularly thin skin?	The eyelids (and the external ears, if we include them in the face).
7	How much thinner than average is (i) the epidermis and (ii) the dermis in these areas?	Both epidermis and dermis are half the usual thickness (that is, in the eyelids they are about 50  m and 600  m respectively).
8	How thick and dense is the subcutaneous tissue in these regions?	In the eyelids very thin and delicate with litte fat. (The subcataneous layer is absent in the pinna except in the lobes).
9	How thick are the lips?	12 mm.
10	How thick are the cheeks?	12 mm.
11	Does the skin or subcutaneous tissue contribute most to the thicknesses?	The subcutaneous layer is 9 - 10 mm thick.
12	How is the extent of the lips defined?	They are the area where the skin if FIRMLY bound to the deeper tissues.
13	Are there external markings indicating the extent of the lips?	The nasolabial folds and labiomental fold (mental = of the chin).
14	What particular change in the firmness of skin attachment occurs on passing from the lips to the cheeks?	The skin becomes somewhat more mobile in the cheeks, but not as free in the front of the neck, for instance.
15	Is the beard different in principal from head hair?	No; both are terminal hair with follicles extending into the subcutaneous layer.
16	How much denser is the hair follicle population on the face (and scalp and neck) than elsewhere on the body?	10 x.
17	How much denser are the hairs on these parts than elsewhere?	About 3 x (many follices are "resting" in a cycle measured in years).
18	Are sweat glands more profuse on the face (and scalp and neck) than elsewhere on the body? why?	At least twice as dense. The head and neck are the principal sites of heat loss. Hands next, then feet.
19	What layer of tissue represents the investing fascia in the face?	The periosteum of the bones of the face.
20	Is the mucosa of the gums facing the vestibule of the mouth superficial or deep to the investing fascia?	Superficial.
21	In what layer do the muscles of facial expression lie?	In the deep half of the subcutaneous tissue.
22	What is the posterior limit of this muscle group?	The nuchal lines on the occiptal bone.
23	What is the anterior (actually inferior) limit of this group?	The chest for a few centimetres below the clavicle; (platysma extends to this level).
24	What is the name of the muscle surrounding and contained in the eyelids?	Orbicularis oculi.
25	What is its action?	It blinks the eyelids and more forcibly, screws them tight shut.
26	What is the name of the muscle surrounding the mouth?	Orbicularis oris.
27	What is its action?	It purses the lips.
28	Where do your find the Buccinator muscle?	In the cheeks, posterior to orbicularis oris.
29	Is it a muscle of facial expression?	Yes.
30	What muscles arise from the zygomatic bone?	Zygomaticus major and z. minor passing down into the upper lip.
31	What muscles arise just below the infraorbital margin of the maxilla?	Levator labii superious and levator labii superious alaeque nasi (alaeque = and also of the).
32	Where does the Levator anguli oris arise?	From the anterior surface of the maxilla BELOW the infraorbital canal.
33	Why is there no "Levator labii inferioris?"	The orbicularis oris opposes the depressor of the lower lip. These are ELEVATORS of UPPER lip and DEPRESSORS of LOWER lip.
34	Locate Risorius, Procerus and Corrugator supercilii muscles.	At angle of mouth, between eyebrows and under inner end of eyebrows.
35	Can you name any other muscles in the face?	Compressor naris, Mentalis, Depressor anguli oris, Platysma.
36	Describe the extent of Platysma.	From corner of mouth to upper chest.
37	From which vessel does the facial artery arise?	The external carotid artery.
38	Is the first part of its course superficial or deep to the mandible?	Deep.
39	Where does it cross the lower border of the mandible?	Immediately in front of the Masseter muscle.
40	What is the inner canthus of the eye?	The inner angle where the two eyelids meet.
41	In its course to the inner canthus does the facial artery run superficial to, deep to or in amongst the muscles of facial expression?	Amongst.
42	Name its branches arising near the angle of the mouth.	The superior and inferior labial arteries.
43	Where does the facial vein terminate? Does it ever lie deep to the mandible?	In the internal jugular vein (usually having coalesced with the lingual vein). No.
44	Name three separate groups of lymph nodes in the face.	Parotid, submandibular; mental.
45	To which group do the outer parts of the eyelids mainly drain?	Parotid.
46	To which group do the inner parts of the eyelids mainly drain?	Submandibular.
47	To which group does the upper lip mainly drain?	Submandibular.
48	To which group does the lower lip mainly drain?	Mental.
49	Which nerve is sensory to the upper eyelid?	Ophthalmic division of trigeminal (V1).
50	Which nerve is sensory to the lower eyelid?	Maxillary division of trigeminal (V2).
51	Which nerve is sensory to the upper lip?	Maxillary, V2.
52	Which nerve is sensory to the lower lip?	Mandibular divisiion of trigeminal V3.
53	Which nerve is sensory to the dorsum ("leading edge") of the nose?	The external nasal branch of V1 (via anterior ethmoidal).
54	Which nerve is motor to the muscles of facial expression?	Facial nerve (VII).
55	Do you think that that is enough questioning about the face?

The Orbit

1	Which bones contribute to the roof of the orbit?	Frontal, sphenoid.
2	Which bones contribute to the floor of the orbit?	Maxilla, Zygomatic (and palatine).
3	Which bones contribute to the medial wall of the orbit?	Maxilla (frontal process), lacrimal, ethmoid and sphenoid.
4	Which bones contribute to the lateral wall of the orbit?	Sphenoid and Zygomatic.
5	What bony elements bound the superior orbital fissure?	Greater and lesser wings and body of sphenoid.
6	What bony elements bound the inferior orbital fissure?	Great wing of sphenoids, zygomatic, maxilla and body of sphenoid.
7	Which bones bound the bony nasolacrimal canal?	Lacrimal, maxilla and inferior concha.
8	What bony elements bound the optic canal?	The root of lesser wing and body of sphenoid.
9	What is the diameter of the eye ball?	24 mm.
10	In which part of the orbit does the eyeball lie?	In the anterior half (of its length).
11	How closely does it approach the orbital walls?	To within 6 mm.
12	What is the bulbar fascia or Tenon’s capsule?	The connective tissue lining of the fibrofatty socket for the eye.
13	About which point does the eyeball move?	Its centre.
14	Name the two major refracting elements of the eye.	The cornea and lens.
15	What medium surrounds the iris?	Aqueous humour.
16	What medium surrounds the optic nerve?	Cerebrospinal fluid.
17	Where is the dura attached to the eyeball?	Immediately medial to the posterior pole.
18	Where do most of the nerves and arteries enter the eyeball?	Immediately about the dural sheath of N.II.
19	To what bony elements is the fibrous annulus (of Zinn) attached?	The body, lesser wing and, by a small area, the great wing of the sphenoid.
20	In what direction does teh superior rectus muscle run?	Fowards and laterally, at an angle of 22½° to sagittal plane.
21	In which quadrant of the eyeball does the superior oblique muscle insert?	Postero-supero-lateral quadrant.
22	Where does the inferior oblique muscle arise?	Immediately lateral to the nasolacrimal canal.
23	Where does it insert?	Into the horizontal meridian immediately lateral to the posterior pole of the eye.
24	Which muscle is innervated by the 4th cranial nerve? by the 6th cranial nerve?	The superior oblique; the lateral rectus.
25	How long approximately are the rectus muscles? How wide?	40 mm; 10 mm.
26	Name three nerves lying between the orbital roof and the fibrous annulus.	Lacrimal, frontal and trochlear nerves.
27	Name three nerves passing through the fibrous annulus. Which one of these has divided into two divisions?	Oculomotor, masociliary and abducens nerves. The oculomotor is divided.
28	Briefly describe the course of the ophthalmic artery.	Through optic canal, along lateral side of optic nerve, over nerve at midpoint to medial wall, then forwards.
29	Which nerve follows essentially the same course?	The nasociliary nerve (but enters orbit through superior orbital fissure).
30	Where is the ciliary ganglion located?	Just lateral to optic nerve, several millimeters behind the eye.
31	What type of neurons does it contain?	Parasympathetic post-ganglionic neurons.
32	What structures does it supply?	The smooth muscle of the ciliary body and iris.
33	What type of tissue fills the interstices of the orbital cavity?	Delicate fibrofatty tissue.
34	Name the firm connective tissue structures forming the basis of the eyelids.	The tarsal plates.
35	What covers the deep surface of these structures?	Conjunctiva.
36	What muscle is found in the eyelids?	Orbicularis oculi + levator palpebrae superiorus.
37	How many rows of eyelashes are present in each lid?	Two or three.
38	Where are the tarsal (Meibomian) glands situated?	In deep grooves in the tarsal plates.
39	At what level does the upper lid lie in relation to this iris and pupil? At what level does the lower lid lie?	Between the top of iris and top of pupil. Just at the bottom of the ribs.
40	What is the vertical and horizontal extent of the conjunctival sac?	About 30 mm each way.
41	Name the structure about which the lacrimal gland is folded or clamped?	The tendon of the levator palpebrae superioris.
42	Do ducts arise from both parts?	Yes.
43	Where do these ducts open?	Into the lateral half of the superior conjunctival fornix.
44	Where are the puncta of the lacrimal ducts located?	At the medial end of the rows of eyelashes.
45	Where do the lacrimal ducts run?	Within the substance of the medial palpebral ligament.
46	Where does the lacrimal sac lie?	In the fossa formed by the lacrimal bone and frontal process of the maxilla.
47	What is the direction of the lateral palpebral ligament?	Forwards from the orbital margin.
48	To what bony structure is the medial palpebral ligament attached?	Over an area several mm in diameter on the frontal process of the maxilla.
49	Set your own question and answer it.

The Mouth

1	Which reference planes bound the mouth?	3, 4, A, B and R (each side)
2	Which reference planes bound the buccal cavity?	3, 4, A, B, and P (each side)
3	What are the functions of the mouth?	Food and liquid intake; accessory air intake; articulation in speech; (investigating environment).
4	Which muscles forms the foundation of the cheek?	Buccinator.
5	What is its nerve supply?	The facial (VIIth) nerve.
6	Which muscle forms the foundation of the lips?	Orbicularis oris.
7	About how thick are the lips and cheeks?	12 mm
8	What type of epithelium is found on the mucosa of the mouth?	Non-keratinizing stratified squamous epithelium.
9	What is the name of the region of the mouth bounded by the lips and cheeks on the one hand and the teeth and gums on the other?	Vesibule of the mouth.
10	What is the name of the region of the mouth bounded by the tongue on the one hand and the lower teeth and gums on the other?	Linguo-alveolar groove.
11	Which bones contribute to the hard palate?	Maxilla and palatine.
12	Name the five major bony elements of the mandible (three are bilateral).	Head, coronoid process, ramus, body and alveolar process.
13	Name the four types of teeth in the adult dentition.	Incisors, canines, premolars and molars.
14	Which belong to the "anterior teeth"?	Incisors and canines.
15	Which belong to the "cheek teeth"?	Premolars and molars.
16	How many roots on an upper permanent molar? What are their positions?	3; lingual, mesiobuccal and distobuccal.
17	How many roots on a lower molar? What are their positions?	2; mesial and distal.
18	Which nerves supply the upper cheek teeth?	The posterior superior alveolar nerves (2 or 3).
19	Which nerve supplies the mucous membrane of the gum immediately lateral to the upper molars?	One of the posterior alveolar nerves (which doesn’t supply teeth).
20	Briefly describe the course of the nerve supplying the upper incisors and canine.	It curves downwards and medially from infraorbital nerve in anterior face of maxilla, passing just below the opening of the nose.
21	Which nerve supplies the gum immediately lateral to the lower molars?	The buccal nerve.
22	Which nerve supplies the mucosa of the part of the vestibule related to the lower anterior teeth?	The mental nerve.
23	Which nerve supplies the skin of the lower lip and chin?	The mental nerve.
24	Which nerve supplies the skin of the upper lip and the related mucous membrane?	The infraorbital nerve.
25	Which nerve supplies the mucosa of the roof of the mouth (hard palate)?	The greater palatine nerve.
26	Which nerve supplies the mucosa of the floor of the mouth including that of the buccal part (anterior two-thirds) of the tongue?	The lingual nerve.
27	Which artery supplies the hard palate?	The greater palatine artery.
28	Which artery supplies the floor of the mouth?	The lingual artery.
29	Which arteries supply the upper teeth?	The superior alveolar arteries.
30	Which artery supplies the lower teeth?	The inferior alveolar artery.
31	Where does that artery arise?	From the maxillary artery in the pterygoid region.
32	Which lymph nodes receive lymph from the mouth?	Retropharyngeal, submandibular and submental.
33	Name the nerve supplying the muscles of the tongue.	Hypoglossal (Cranial nerve XII).
34	Where does it arise?	From the anterior aspect of the medulla.
35	How does it leave the cranium?	Through the hypoglossal (anterior condylar) canal.
36	How low does it descend in the neck?	To the level of the great horn of the hyoid bone.
37	What special features are there of the mucosa of the dorsum of the tongue?	Papillae.
38	Is there a submucosa in the tongue?	No.
39	Which salivary gland opens into the vestibule?	The parotid.
40	Which salivary glands open into the buccal cavity?	The submandibular and sublingual glands.
41	Which gland has its duct opening near the second upper molar tooth?	The parotid.
42	Which gland has its duct opening below and behind the medial lower incisor?	The submandibular.
43	Which salivary gland has little mucus in its secretion?	The parotid.
44	What muscle forms the floor of the mouth?	The mylohyoid.
45	Where does its nerve supply arise?	From the inferior alveolar nerve.
46	Which other muscles lie in the floor of the mouth?	The anterior belly of digastric; the geniohyoid.
47	From which embryological structure does the floor of the mouth arise?	The mandibular (1st) arch.
48	From which embryological structure does the roof of the mouth arise?	The maxillary process of the mandibular arch.
49	Into which region does the mouth open posteriorly?	The isthmus of the fauces (of the pharynx).
50	Do you require any further questions on the mouth?

The Nose

1	Name the planes bounding the lower nasal block.	2, 3, A, B, and P (on each side).
2	Which bones enclose the olfactory part of the nose?	The ethmoid, with sphenoid behind and maxilla and nasal bones in front.
3	Name the bones contributing to the external nose.	Nasal bones and maxillae.
4	Name two major cartilages of the external nose.	Lateral nasal (from septal) and greater alar cartilage.
5	What is the name of the region immediately inside the nostril?	The vestibule of the nose.
6	Which bones contribute to the nasal septum?	Ethmoid and vomer.
7	What other component contributes to the skeleton of the nasal septum?	The septal cartilage.
8	Which is the largest nerve on the septum? Where does it end?	The nasopalatine; on the incisive pad.
9	About how wide (from medial to lateral) is the frontal sinus?	30 mm
10	In which part(s) of the frontal bone does it lie?	In the squama (underlying the forehead) and in the orbital plate.
11	Where does it open into the nose?	Into the anterior part of the infundibulum (c.60%) or immediately in front of it into middle meatus (c.40%).
12	Which is the longest meatus?	The inferior.
13	Which is the shortest?	The superior (or supreme meatus if present).
14	What structure forms the lower part of the lateral wall of the middle meatus?	The uncinate process.
15	What structure forms the upper part?	The bulla.
16	Name the gap between these two.	The hiatus semilunaris.
17	Where do the posterior ethmoidal air cells open?	Into the superior meatus.
18	What do we call the region on each side from which the sphenoidal air sinus opens.	The sphenoethmoidal recess.
19	Which is the most voluminous paranasal air sinus?	The maxillary sinus.
20	Where does it communicate with the nose?	In the infundibulum.
21	What structures traverse the cribriform plate?	The olfactory nerves and the anterior ethmoidal nerve and vessels.
22	Name the cranial nerve supplying the nose?	The trigeminal.
23	Which area does its first division supply?	The external nose.
24	What is the extent of the olfactory sensory area?	Over the superior and much of middle concha and opposing parts of septum.
25	Name the branch of the maxillary artery supplying the nose.	The sphenopalatine artery.
26	Name the nerves supplying the superior and middle conchae.	The posterior superior lateral nasal nerves.
27	What type of epithelium lines the nasal cavity (except the lower vestibule)?	Respiratory epithelium.
28	Describe the nature of the nasal mucosa.	Thick and vascular, with many glands.
29	Which nerves supply skin of the external nose?	The external nasal branch of the anterior ethmoidal nerve; the infractrochlear; and the external nasal branches of the infraorbital nerve.
30	Which of them supply skin inside the nostril?	Those of the infraorbital nerve.
31	What areas of the nose are supplied by the anterior superior alveolar nerve?	Small areas on the lateral and septal walls at the anterior end of the inferior concha and the floor between.
32	What supports the mucosa of the lateral wall of the choanal part of the nose?	The medial pterygoid plate.
33	Which reference planes bound the choanal part of the nose in front, and above?	Plane B and Plane 2.
34	Which nerves supply this part of the nose?	The posterior nasal branches of the pterygopalatine ganglion.
35	To what structures are the lateral nasal cartilages attached?	They are continuous with the septal cartilage and are firmly attached to the nasal bones and the frontal process of the maxilla.

---

Aortic Arch Derivatives:

1st: part of MAXillary artery
2nd: stapedial artery and hyoid artery
3rd: Common carotid artery and proximal internal carotid
4th: on left, aortic arch; on right, proximal right subclavian
6th: proximal part of pulmonary arteries and ductus arteriosus

1st arch is MAXimal
Second = Stapedial
C is third letter of the alphabet
4th arch (4 limbs) = systemic
6th arch = pulmonary and pulmonary-to-systemic shunt (ductus arteriosus)

Mastication Muscles (all innervated by V3):
- Masseter, teMporalis, Medial pterygoid (these close jaw)
- lateral pterygoid (this is the only one that lowers)
- In summary, M's munch. Lateral Lowers.

Palat muscles:
All muscles with palat in their name (except tensor veli palatini via CN V) are innervated by CN X. [Explained in branchial stuff below]

Glossus muscles:
All muscles with glossus in their name (except palatoglossus via CN X) are innervated by CN XII. [Also explained below]

Carotid Sheath:
You've seen it before: VAN
- Internal Jugular vein (lateral)
- Common carotid (medial)
- Vagus Nerve (posterior)

Branchial Stuff (with mnemonics):

Branchial Clefts derived from ectoderm
Branchial Arches derived from mesoderm and neural crest
Branchial Pouches derived from endoderm

CAP covers from outside to inside: Cleft = ecto, Arch = meso, Pouch = endo

Arches (mesoderm):

Branchial arch 1 derivatives: (lots of M's)
Meckel's cartilage: Mandible, Malleus, incus, sphenoMandibular ligament
Muscles: Muscles of Mastication (temporalis, Masseter, lateral and Medial pterygoids), Mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini
Nerve: CN V3 (V2 also involved)

Branchial arch 2 derivatives: (lots of S's)
Reichert's cartilage: Stapes, Styloid process, leSSer horn of hyoid, Stylohyoid ligament
Muscles: muscles of Silly facial expression, Stapedius, Stylohyoid, poSterior belly of digastric
Nerve: CN VII

Branchial arch 3 derivatives: (This is the easiest one)
Cartilage: greater horn of hyoid
Muscle: stylopharyngeus
Nerve: CN IX (think of pharynx - stylopharyngeus innervated by glossopharyngeal nerve)

Branchial arch 4 to 6 derivatives:
Cartilage: thyroid, cricoid, arytenoid, corniculate, cuneiform
Muscle: pharyngeal constrictors, cricothyroid, levator veli palatini, intrinsic muscles of larynx, trapezius, SCM (See note below)
Nerve: 4th arch - CN X, 6th arch - recurrent laryngeal branch of X (See note below about XI)

Note: All of the intrinsic muscles of larynx innervated by the inferior laryngeal nerve of CN X (a continuation of the recurrent laryngeal nerve) EXCEPT the cricothyroid muscle, innervated by external branch of the superior laryngeal nerve (branch of CN X). The cricothyroid specifically comes from the 4th arch, and that is why it has separate nerve innervation than the intrinsic laryngeal muscles which come specifically from the 6th arch. But if asked on an exam, just group all of these muscles into 4th-6th arch.

Note: When we talk about arch 4 and 6, it is acceptable to lump everything together into one big group: 4-6. You will see in your green notes that X and XI are nerves of the 4th-6th arch. Technically speaking, the accessory fibers of XI are the motor fibers that are carried by the vagus to the muscles of the larynx. So, when asked about the nerve of the 4th - 6th arch, just say X(XI). See p 180 green notes, Netter 121.

Note: Branchial Arch 5 makes no developmental contributions.

Summary:
Arch 1: V2, V3
Arch 2: VII
Arch 3: IX
Arch 4, 6: X(XI)

Note: This is the simplest way to conceptualize head/neck muscle innervation. Actually, this is analogous to compartmentalization of the limbs.

Clefts (ectoderm):

1st cleft: external auditory meatus
2nd - 4th clefts: temporary cervical sinuses, obliterated ultimately by 2nd arch mesenchyme

Note: Persistent cervical sinus can lead to branchial cyst in the neck

Pouches (endoderm):

1st pouch: middle ear cavity, eustachian tube, mastoid air cells (endoderm lined structures of the ear)
2nd pouch: palatine tonsil epithelium
3rd pouch: inferior parathyroids (from dorsal wings), thymus (from ventral wings)
4th pouch: superior parathyroids
5th pouch: ultimobranchial bodies - This is where a subset of neural crest cells migrate to ultimately become the C cells of the thyroid (calcitonin producing cells, part of the neuroendocrine system -HISTOLOGY correlation)

"Mnemonic": 3rd pouch: 3 structures - thymus, Left and Right inferior Parathyroids

Pretrematics:

Remember that each arch has a cranial nerve (discussed above)
There are pretrematic branches of these nerves that "invade" the arch right before it.

1. Ophthalmic division of V1 leaves V2 and V3 behind in the first arch and associates with the optic cup in front of the first arch (gives us tactile sensation to the eye)

2. A pretrematic from arch 2 (VII territory) invades arch 1 (V3 territory). This is the chorda tympani (VII) which joins the lingual nerve (V3) and gives us taste.

3. A pretrematic from arch 3 (IX territory) invades arch 2 (VII territory). This is the tympanic nerve (IX) which provides sensory innervation to the middle ear and auditory tube. Also remember the tympanic plexus which is a mix of VII and IX nerves (Netter 117, 119)

Cervical Plexus / Ansa Cervicalis (Netter 27)

Plexus divided into muscular and cutaneous branches
Cutaneous (C2-3): Great auricular, lesser occipital, transverse cervical nerves
Cutaneous (C3-4): Supraclavicular nerves
Motor: Ansa Cervicalis (C1-3) - innervates infrahyoid (strap) muscles of the neck; and Phrenic nerve (C3-5)

Muscles innervated by ansa (C1-3):
-geniohyoid (C1 via hypoglossal nerve)
-thyrohyoid (C1 via hypoglossal nerve; remember that XII travels right on top of the ansa - the superior root of the ansa is actually called the descendens hypoglossi) These are the only two hyoids innervated by C1 via XII.
-sternothyroid (C1-3)
-sternohyoid (C1-3)
-omohyoid (C1-3)

What hyoid muscles are not innervated by the ansa?
- mylohyoid (1st arch, V3)
- stylohyoid (2nd arch VII (cervical branch))

Thyroid Stuff:

Thyroid develops from the thyroid diverticulum which forms in the floor of the foregut (no branchial pouches involved), descends into neck.

Connected to tongue by thyroglossal duct - disappears and becomes foramen cecum

Most common ectopic thyroid site is tongue

Tongue Stuff:

Anterior 2/3 formed from 1st branchial arch. Therefore, tactile sensation via V3, taste via VII. (The chorda tympani joins lingual nerve).
Posterior 1/3 formed from 3rd and 4th arches. Therefore, sensation and taste mostly via IX, most posterior via X.
All motor from XII.

Cleft Lip/Palate:

Cleft lip - failure of fusion of maxillary and medial nasal processes
Cleft palate - failure of fusion of lateral palatine processes, nasal septum, and/or median palatine process

Larynx:

7 muscles you need to know:

Cricothyroid - stretch and tense vocal cord (only muscle innervated by external laryngeal n.)
Posterior Cricoarytenoid - (only muscle to ABduct vocal cord)
Lateral Cricoarytenoid - ADduct vocal fold
Thyroarytenoid - relax vocal fold
Vocalis (formed from thyroarytenoid) - alters fold during phonation
Oblique arytenoid - close inlet
Transverse arytenoid - close inlet (oblique and transverse perform same task)

Motor: All muscles except cricothyroid (external branch of superior laryngeal n.) innervated by recurrent laryngeal n. All X(XI).
Sensory: The internal branch of the superior laryngeal nerve will receive sensory information above the vocal fold where the recurrent will receive sensory info below the folds.

Parasympathetics and Ganglia:

The important take home point: the trigeminal nerve acts as a carrier for parasympathetic fibers from III, VII, IX. The trigeminal itself contains no inherent parasympathetic activity.

The major function of parasympathetics in the head is to act as secretomotor to the lacrimal gland, salivary glands, and mucus glands of the oral and nasal cavities and sinuses. It will increase secretion.

VII (Netter 117):
The origin of parasympathetic fibers in VII comes from the nervus intermedius. It merges with the facial nerve at the sensory geniculate ganglion. The greater petrosal nerve continues on and merges with the deep petrosal nerve (totally sympathetic, postganglionic coming off the carotid plexus) in the pterygoid canal to form the vidian nerve. The vidian nerve enters the pterygopalatine ganglion and parasympathetics synapse. Postganglionic autonomics exit the fossa via V2 through five exits (listed below) to get to the mucus glands of nose and palate, and lacrimal gland.

Two entrances of the Pterygopalatine Fossa:
Pterygoid Canal (vidian nerve)
Entrance of maxillary nerve through foramen rotundum

Five Exits of the Pterygopalatine Fossa:
Sphenopalatine foramen - (nasal branches of V2 going to nasal cavity)
Greater palatine foramen - (greater palatine n. of V2 going to hard palate)
Lesser palatine foramen - (lesser palatine n. of V2 going to soft palate)
Inferior orbital fissure - (zygomatic n. of V2 going to lacrimal gland)
Palatovaginal canal - (pharyngeal branch of V2 going to nasopharynx)

Cranial Nerve Lesions:

VII Lesion (Bell's Palsy) - cannot operate muscles of facial expression. Affected muscles on same side of lesion
X lesion - Ask to say "Ah" - uvula will point away from lesion
XI lesion - head will be turned toward lesion (SCM action)
XII lesion - stick out tongue - tongue will point to lesion

Cranial Foramina:

Know the foramina for all of the cranial nerves. In addition, know the stylomastoid foramen, petrotympanic fissure, and foramen spinosum and their contents.

Clinical Correlations:

I suspect a patient is faking neck injury. How can I tell?
- Most patients do not know about the function of the SCM. The contralateral muscle turns the head away from it. First. ask the patient to shrug his/her shoulders (trapezius, XI). Say for example the patient cannot shrug the left shoulder. Ask the patient to turn his/her head left or right (SCM, XI) If the patient says he/she has trouble turning the head to the left, the person is faking. If he/she cannot turn it to the right, the injury is probably real.

What are some significant features of the carotid bifurcation?
- Location of the carotid body - an oxygen chemoreceptor - sensory info carried back to CNS via CN IX, X
    - Location of carotid sinus - a pressure receptor - sensory info carried to CNS via CN IX, X
    - Place where clots can form (think turbulent flow). Performing a bilateral carotid massage on an older patient may actually throw emboli into the circle of Willis. A lot of good your anastomoses are going to do in this situation...

What would be the clinical presentation of a patient with bilateral recurrent laryngeal nerve damage?
- Acute dyspnea - the vocal muscles have stretched and tensed from unopposed cricothyroid, closing off the airway.

What structure must I puncture in a tracheotomy?
    - Cricothyroid ligament

What are three symptoms from evulsed T1 (besides clawhand)
    - ptosis
    - miosis
    - anhydrosis

Why does both a sympathetic and parasympathetic lesion to the eye cause ptosis?
- levator palpebrae superioris (skeletal muscle - innervated by CN III)
    - tarsal or Mueller's muscle (smooth muscle - innervated by sympathetics)

Questions:

1. Which of the following courses through the jugular foramen?

A. CN VII
B. inferior sagittal sinus
C. middle meningeal artery
D. straight sinus
E. CN X

2. The chorda tympani branch of CN VII carries:

A. motor fibers to the stapedius muscle
B. parasympathetic fibers to the parotid gland
C. sensation from the tympanic membrane
D. taste from the anterior two-thirds of the tongue
E. taste from the posterior one-third of the tongue

3. Sensory innervation of the larynx is by branches from the

A. CN V
B. CN VII
C. CN VIII
D. CN IX
E. CN X

4. In a patient with an aneurysm of the aortic arch associated with hoarseness, one would immediately look for paralysis of the left:

A. anterior belly of the digastric muscle
B. cricothyroid muscle
C. posterior belly of the digastric muscle
D. posterior cricoarytenoid muscle
E. omohyoid muscle

5. Following a blow to the side of the head, extradural hemorrhage is usually caused by bleeding from the:

A. cavernous sinus
B. emissary veins (connections between intracranial sinuses and external veins)
C. middle cerebral artery
D. middle meningeal vessels
E. superior sagittal sinus

6. A patient with Bell Palsy (paralysis of CN VII) experiences food collecting in his oral vestibule. Paralysis of which muscle is most likely causing this muscle?

A. buccinator
B. masseter
C. mentalis
D. orbicularis oris
E. zygomaticus major

7. Pain impulses from the tip of the tongue would most likely be carried to neurons in which of the following ganglia?

A. geniculate
B. otic
C. pterygopalatine
D. superior vagal
E. trigeminal

8. Each of the following nerves supplies muscle derived from the branchial arches EXCEPT the

A. VII
B. IX
C. XII
D. V
E. X

9. Congenital absence of the parathyroids is most likely accompanied by absence or poor development of the

A. lungs
B. Anterior pituitary
C. thyroid gland
D. nasopharyngeal portions of the eustachian tube
E. thymus

10. Endoderm contributes to the formation of each of the following EXCEPT the

A. eustachian tube
B. liver
C. parathyroid glands
D. tooth enamel
E. trachea

11. In a newborn, obstruction of the pharynx caused by a large mass in the posterior third of the tongue is most likely a result of

A. branchial cyst
B. ectopic parathyroid tissue
C. ectopic thymic tissue
D. ectopic thyroid tissue
E. hypertrophied lymphoid tissue

12-14. Mechanisms involved in swallowing:

A. Closure of nasopharynx from oropharynx
B. Depression of the larynx and hypopharynx to produce negative pressure in the pharynx
C. Elevation of the larynx and hypopharynx
D. Movement of a bolus of food posteriorly into oropharynx
E. Protection of the airway

12. Styloglossus muscle

13. Tensor veli palatini and superior constrictor muscles

14. Stylohyoid and digastric muscles

Questions with more than one answer:

15. A fracture of the cribriform plates that tears the meninges is likely ot result in
A. loss of sense of smell
B. rupture of nasolacrimal duct
C. leakage of CSF into nasal cavity
D. injury to maxillary division of  CN V

16. The nerve supply of the tongue is derived, in part, from the nerve of the:
A. First branchial arch (V3)
B. Second arch (VII)
C. Third arch (IX)
D. Fourth arch (X)

17. The first branchial arch contributes to the formation of the:
A. malleus and incus
B. maxilla and mandible
C. muscles of mastication
D. muscles of facial expression

18. The intermaxillary segment of the developing upper jaw contributes to the formation of:
A. Philthrum of the lip
B. Primary or anterior palate
C. Premaxillary part of the maxilla
D. Posterior or secondary palate