Fractures

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General Classifications of Bones Long Bones -- "longer than they are wide:" clavicle, humerus, radius, ulna, femur, tibia, fibula, metatarsals, metacarpals. Purpose: provide support and serve as  the interconnected set of levers and linkages that allow us to create movement. (formed from hyaline/articular cartilage) Short Bones: carpals and tarsals: consist mainly spongy bone covered with a thin layer of compact bone. Purpose: allow movement, provide elasticity, flexibility, & shock absorption. Flat Bones:  ribs, sternum and scapula. Purpose: protect and provide attachment sites for muscles. Irregular Bones:  skull, pelvis, and vertebrae. Purposes:  support weight, dissipate loads, protect the spinal cord, contribute to movement and provide sites for muscle attachment. Sesamoid Bones: a short bone embedded within a tendon or joint capsule, i.e. patella. Purpose: alter the angle of insertion of the muscle. Joints Joints are classifiied into three groups: 1)  immovable (fibrous) joints, e.g. skull bones; 2) slightly movable (cartilagenous) joints, e.g. intervertebral discs; and 3) freely movable (synovial) joints, e.g. limb joints. Synovial joints permit the greatest degree of flexibility and have the ends of bones covered with a connective tissue (synovial membrane) filled with joint (synovial) fluid. A typical synovial joint, seen at right, has four main featues: joint capsule -  the joint enclosure, reinforced by and strengthened with ligaments synovial membrane -  a continuous sheet of connective tissue lining the capsule; its cells produce synovial fluid that lubricates the joint and prevents the two cartilage caps on the bones from rubbing together synovial fluid - produced by the synovial membrane, the fluid lubricates the joint. In the normal joint, very little fluid (less than 5cc) exists in the cavity. hyaline (articular) cartilage - where the bones actually "meet"       Graphics modified from: The InnerBody: Anatomy Tutorials - Skeletal System   (Front View)  (Back View) Human Skeleton The average human adult skeleton consists of 206 bones,  attached to the muscles by tendons.  Babies are born with 270 soft bones - about 64 more than an adult. These will fuse together by the age of twenty or twenty-five into the 206 hard, permanent bones.  The skeleton has two main parts: the axial skeleton and the appendicular skeleton. The axial skeleton consists of the skull, the spine, the ribs and the sternum (breastbone) and includes 80 bones. The appendicular skeleton, consisting of 126 bones,  includes two limb girdles (the shoulders and pelvis) and their attached limb bones.  Axial Skeleton (80 bones) skull - consiting of 1) the cranium (which encloses and protects the brain) and 2) the facial skeleton. The upper teeth are embedded in the maxilla; the lower teeth, in the mandible. mandible (jaw) - the only freely movable bone of the skull ribs, sternum (breastbone) - comprising  the "thorax"/thoracic cage, protecting the heart and lungs vertebral column - the "spine"      The vertebral column (illustrated below and to the left)  transmits the body weight from the head, throax, and abdomen to the lower extremities and encloses and protects the spinal cord. Each vertebra has essentially the same basic components, with some variation based on location and allowed movements. The vertebral body and the neural arch encircle the vertebral foramen. Stacked one on top of the other, these foramina form the vertebral canal, where the spinal cord resides. Several structures strengthen the attachments between vertebrae: 1) anterior longitudinal ligaments in front of vertebral bodies and discs; and 2) posterior longitudinal ligaments behind bodies and discs; 3) the compact bone of the disc itself; 4) the interlocking hyaline cartilage surfaces of the neural arch joints; and 5) the ligaments attaching spinous processes to transverse processes.The intervertebral discs provide shock absorption.   Anterior Skull Lateral  Skull Vertebral Column The orientation of the neural arch joints determines allowable motions: 1) the cervical spine () to rotate, flex forward, flex sideways, and extend backward; 2) the thoracic spine () to rotate; and 3) the lumbar spine () to flex forward, flex sideways, and extend backward. The sacrum () has a dual character, being part of both the vertebral column and pelvis. As such, it transmits the upper body weight to the lower exterminites. Appendicular skeleton (126 bones, 64 in the shoulders and upper limbs and 62 in the pelvis and lower limbs) Upper Extremity - The arms (humerus - upper arm bone) are ultimately attached to the thorax,  via synovial joints, at the collarbone (clavicle) and shoulder bone (scapula) (shoulder joint). The scapula is attached to the thoracic cage only by muscles.  The elbow joint unites the humerus with the two lower arm bones - the ulna and radius. Three sets of joints connect the radius and ulna to the bones of the palm (metacarpals), via the eight small wrist carpals. Further, the knuckles (metacarpophalangeal, or MCP, joints) connect the metacarpals to the proximal phalanx of the fingers. Each finger has 3 phalanges (proximal, middle, distal), except the thumb which has only two. shoulder/ scapula arm and forearm, elbow hand Lower Extremity - The pelvis transmits the upper body weight from the sacrum (at the sacroiliac joint) to the legs. It begins as 3 hip bones (ilium, ischium, and pubis) which fuse together when growth is completed. The hip joint unites the pelvis to the thigh bone (femur); the knee joint, which includes the knee cap (patella), links the femur to the lower leg bones - the tibia and fibula. The ankle joint links the lower leg bones to the talus. The body weight is then transmitted to the heel (calcaneous) and to the balls of the feet via the tarsal and metatarsal foot bones. The toes have a phalangeal structure like the fingers. pelvic girdle thigh and leg. knee,  foot/ankle/toe Radiologic Anatomy Upper Extremity   Shoulder  Elbow & Forearm  Wrist  Hand  Spine  Cervical & Lumbar Spine  Lower Extremity  Pelvis and Hip  Knee  Ankle  From