Do you know our shoulders are the third most common area of musculoskeletal injury? Rotator Cuff Shoulder Pain accounts for a majority of shoulder injuries.
Let’s learn about shoulder joint anatomy.
The shoulder joint is a ball and socket joint. It is highly mobile and unstable, like a golf ball and tee (a stand used to support the ball). The shoulder joint is made up of 3 bones: scapula (shoulder blade), clavicle (collarbone), and Humerus (upper arm bone).
The large ball (top of humerus) sits in the shallow socket (the tee) of the scapula, with stability provided by a number of structures which include the rotator cuff.
What is the rotator cuff and its role?
The rotator cuff is a group of 4 deeper shoulder muscles, that sit under your larger shoulder muscles. They consist of the: subscapularis – which performs internal rotation of the shoulder, supraspinatus – performs initial 0-15 degrees of shoulder abduction, infraspinatus – performs external rotation of the shoulder and teres minor – performs external rotation of the shoulder.
| Deeper Shoulder Muscles | Main Function |
| Subscapularis | performs internal rotation of the shoulder |
| Supraspinatus | performs initial 0-15 degrees of shoulder abduction |
| Infraspinatus | performs external rotation of the shoulder |
| Teres minor | performs external rotation of the shoulder. |
The tendons (connector of muscle to bone) of the rotator cuff muscles form a covering (cuff) to surround the top of the humerus. The rotator cuff stabilises the shoulder joint by enclosing the ball to the tee. As the shoulder moves, the cuff gets activated to stop the humerus from excessively moving. Injury to the rotator cuff decreases shoulder stability, which makes the top of the humerus move upwards during shoulder movement. As a result, the compression of the shoulder joint causes pain and further rotator cuff damage.
