The Rotator Cuff
When I was in Cambodia, one of our group members, Craig, tore his rotator cuff badly and ended up in agonizing pain. He became an overnight patient in a Cambodian hospital not once, but twice. Lets explore the job of the rotator cuff.
The four rotator cuff muscles secure the humeral head into the shallow glenoid cavity. They are intrinsic shoulder muscles, the tendons of which gather together to “cuff” the shoulder joint and provide stability for our complex arm movements. The 4 muscles are referred to as the SITS muscles (supraspinatus, infraspinatus, teres minor and subscapularis) and all of them, except for the supraspinatus, mainly function to assist with rotation.
The supraspinatus (which I suspect Craig severely tore) is a band of muscle, which occupies the top fossas of the scapula and attaches to the middle (greater tubercle) of the humeral head .The supraspinatus abducts the arm with the help of the deltoid.
The infraspinatus lays in the fossa below the spine of the scapula and is partially covered by the deltoid and trapezius. It is a strong lateral rotator or the upper arm bone.
The teres minor is a long lateral muscle that runs below the infraspinatus on the lateral border of the scapula and assists with lateral rotation. It also attaches to the head of the humerus on the greater tubercle, next to the infraspinatus.
The subscapularis is a thick muscle that lines the anterior wall of the scalupa and forms part of the posterior wall of the axilla. It’s the primary medial rotator of the arm and assists with adduction and also attaches to the humerus,
These 4 rotator cuff muscles all work together and hold the humeral head in the glenoid fossa; and assist with the actions of abduction, adduction, lateral and medial rotation. Traumatic injury is very possible, especially with the supraspinatus, and degenerative tendonitis is also quite common- especially with repetitive use above the horizontal line. Degenerative tendonitis prevents a person from smoothly lowering an abducted arm, and a tear of the supraspinatus will prevent initiation of abduction.
With Craigs permission I will update us with news of his rotator cuff.