Rotator cuff tear

The rotator cuff refers to a group of four muscles and their tendons, which help to stabilize the shoulder when it’s moving particularly during rotational motion. So, a rotator cuff tear is when one or more of the tendons of the muscles of the rotator cuff are torn.

The shoulder is a complex of bones, ligaments, muscles and their tendons that all work together to connect the upper limb to the chest, allowing necessary movement and providing stability.

The round head of the humerus fits and rotates inside the shallow glenoid cavity of the scapula. Just above the glenoid cavity, the scapula extends two bony processes; the acromion and the coracoid processes which serve as attachment for ligaments and muscle tendons.

The ligaments of the capsule of the glenohumeral joint hold the head of the humerus inside the glenoid cavity. The coracoacromial ligament forms an arch between the coracoid process and the acromion and it prevents the head of the humerus from upward dislocation.

In addition to these ligaments, the shoulder is supported by the four rotator cuff muscles, also called the SITS muscles, for Supraspinatus, Infraspinatus, Teres minor, and Subscapularis.

The SITS muscles form a cuff that surrounds the head of the humerus to make it stable and help it move, specifically in abduction, as well as internal and external rotation. Below the acromion lies the acromial bursa, which is a small sac filled with rubbery synovial fluid, that provides lubrication and prevents the rotator cuff tendons, especially the supraspinatus tendon, from rubbing against the acromion as the joint moves.

A rotator cuff tear may occur when the tendons are violently stretched like when you jerkily lift up something which is too heavy, or accidentally fall on an outstretched arm. This most commonly affects the supraspinatus tendon at its insertion on the greater tubercle of the head of the humerus, because it’s under a lot of tension when the shoulder is abducted.