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The supraspinatus muscle performs abduction of the arm, and pulls the head of the humerus medially towards the glenoid cavity. [5] It independently prevents the head of the humerus from slipping inferiorly. [5] The supraspinatus works in cooperation with the deltoid muscle to perform abduction, including when the arm is in an adducted position. [5]
Supraspinatus, 12. Subscapularis, 13. Infraspinatus, 14. Teres minor), 15. Biceps muscle. The rotator cuff (SITS muscles) is a group of muscles and their tendons that act to stabilize the human shoulder and allow for its extensive range of motion. Of the seven scapulohumeral muscles, four make up the rotator cuff. The four muscles are ...
The supraspinous fossa (supraspinatus fossa, supraspinatous fossa) of the posterior aspect of the scapula (the shoulder blade) is smaller than the infraspinous fossa, concave, smooth, and broader at its vertebral than at its humeral end. Its medial two-thirds give origin to the Supraspinatus.
When the arm is raised, the subacromial space (gap between the anterior edge of the acromion and the head of the humerus) narrows; the supraspinatus muscle tendon passes through this space. [6] Anything that causes further narrowing has the tendency to impinge the tendon and cause an inflammatory response, resulting in impingement syndrome.
The muscles of the rotator cuff are supraspinatus, subscapularis, infraspinatus, and teres minor. The cuff adheres to the glenohumeral capsule and attaches to the humeral head. The shoulder must be mobile enough for the wide range actions of the arms and hands, but stable enough to allow for actions such as lifting, pushing, and pulling.
The supraspinatus also originates on the spine of the scapula. It inserts on the greater tubercle of the humerus, and assists in abduction of the shoulder. The pectoralis major, teres major, and latissimus dorsi insert at the intertubercular groove of the humerus. They work to adduct and medially, or internally, rotate the humerus.
The greater tubercle of the humerus is the outward part the upper end of that bone, adjacent to the large rounded prominence of the humerus head. It provides attachment points for the supraspinatus, infraspinatus, and teres minor muscles, three of the four muscles of the rotator cuff, a muscle group that stabilizes the shoulder joint.
The role of the supraspinatus is to resist downward motion, both while the shoulder is relaxed and carrying weight. [28] Supraspinatus tears usually occurs at its insertion on the humeral head at the greater tubercle. Though the supraspinatus is the most commonly injured tendon in the rotator cuff, the other three can also be injured at the ...