The supraspinatus muscle

(M. supraspinatus)

The supraspinatus muscle is a skeletal muscle which runs almost horizontally above the shoulder. It is a muscle of the rotator cuff and makes stabilization of the head of the humerus in the shoulder joint possible. It fulfills the function together with the M. teres minor, the M. infraspinatus, and the M. subscarpularis. The supraspinatus muscle of a human being is completely covered by the M. trapezius. Its function is to assist the M. deltoideus in abducting the arm from the body and it supports shoulder muscles situated on the backside for outer rotation of the arm in the shoulder.

The tendon of the M. supraspinatus often plays an important role for painful problems in the shoulder. It is especially permanent overhead working or repetitive throwing activities (all arm motions beyond the horizontal) which cause an increased friction and repeated clamping in the shoulder zone. The bursa, which is situated between the tendon and the bone structure (acromion), is irritated for stress. This can cause irritations, swellings, and inflammations of tendon and bursa (Bursitis subacrominalis). The space of the passage of the tendon is constricted and painful impingement symptoms are caused. A sharp pain while trying to grasp into the back pocket is a typical sign of the impingement syndrome.  

At advanced age, the tendon often tears (also spontaneously) because of degenerative changes (due to wear). Before a tendon tears, it is often a painful interference of functions produced, caused by clamping of tendons. The supraspinatus tendon is clamped between acromion and head of the humuerus. A stiff shoulder is caused, a so called "frozen shoulder".

M. supraspinatus