Shoulder Joint Lab Report

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Anatomy of the shoulder

The shoulder joint, as it is commonly called, is not a single joint but a complex arrangement of bones, ligaments and musculotendinous units that called the shoulder girdle. The primary role of the shoulder girdle is to provide a tremendous range of motion for positioning the upper extremity in space. The shoulder girdle also provides power and support for the upper extremity throughout and at the extremes of the range of motion. (19) The shoulder girdle includes three bones (scapula, clavicle, and proximal humerus), three joints (glenohumeral, acromioclavicular and sternoclavicular), an additional articulation (scapulothoracic) and some 17 musculotendinous units. These individual elements function in a synchronous and interdependent manner to maximize the power and range of motion of the shoulder girdle.(19)
 glenohumeral joint (shoulder joint):

a- Humeral head: Articular
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The proximal origin of the muscle is on the spinous processes of thoracic vertebrae 7–12, the thoracolumbar fascia, the iliac crest, and the lower ribs (Figure14). The tendon is attached to the humerus anteriorly floor of bicipital groove. The tendon is either wing-like or quadrilateral. Most of the deep surface of the tendon of the latissimus dorsi is separated from the underlying tendon of the teres major muscle by a bursa. The latissimus dorsi has several different functions, all of which involve movements of the arm. The primary function is the adduction of the arm, another function of the latissimus dorsi is extension of the arm, as in swinging the arm toward the back. Finally, the latissimus dorsi medially rotates the arm. The latissimus dorsi is supplied by the sixth, seventh, and eighth cervical nerves through the thoracodorsal (long scapular) nerve a branch from posterior cord C 6, 7, and 8.

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