| A | B |
|---|
| the upper extremity is interesting from a functional point of view because of the | interplay among the various joint and segments necessary for smooth, efficient movement. for example, movements of the hand are made through proper positioning of the elbow, shoulder and shoulder girdle |
| the upper extremity consists of: | shoulder complex - elbow - wrist - hand |
| major joints of shoulder complex | scapulothoracic joint - sternoclavicular joint - acromioclavicular joint - glenohumeral joint |
| movement at shoulder complex is generally generated at...altough | all joints at same time. although possible to create a small amount of movement at any one of major joints |
| the four articulations of the shoulder complex (acting in concert) provide | nearly global range of motion of the shoulder |
| the sum of the shoulder range of motion is | greater than the motion available at any single articulation |
| movement of the spine can further | extend the positions available to the humerus |
| the full shoulder function involves | considerable more motion than that required for many daily activities |
| normal motion at all four joints is required for | full shoulder function |
| although normal motion at all four joints is required for full shoulder function, other joints are | capable of compensatory motion when function at one or more joints is limited |
| glenohumeral joint is a...joint between the and the... | is a synovial joint between the head of the humerus and the glenoid fossa of the scapula |
| glenohumeral joint consists of | it consists of a nearly hemispheric convex humeral articular surface and a bone and soft tissue socket |
| glenohumeral joint is a...constrained ball and socket joint with a ....rom | is a minimally constrained ball-and-socket joint with a considerable range of motion |
| glenoid fossa is a | the glenoid fossa is a cartilage covered bony (relatively shallow) depression |
| although the glenoid fossa is deepened by the labrum, its shallowness allows | significant freedom of movement of the humeral head |
| actual contact surface between glenoid fossa and humeral head is | rather small |
| factors important for the stability of the glenohumeral joint: | adequate size of the glenoid fossa - posterior tilt of the glenoid fossa - humeral head retroversion - intact capsule and glenoid labrum - function of muscle that control the A-P position of the humeral head |
| thre types of motion of glenohumeral joint | rotation, rollin, translation |
| surface motin of gh joint is primarily...but some ...and...also take place | surface motion is primarily rotational but some gliding and rolling also take place |
| rotation of gh joint | contact point on the glenoid surface remains constant while the contact point on the humeral head changes |
| rolling of gh joint | the contact points on each of the surfaces changes by an equal amount |
| translation (gliding) gh joint | contact point on the humeral head remains the same while the contact point on the glenoid surface changes |
