Science Fair Project Encyclopedia
These muscles all connect to the head of the humerus forming a cuff at shoulder joint. They are important because they hold the head of the humerus in the small and shallow glenoid fossa of the scapula. The rotator cuff is continuous with the joint capsule of the shoulder.
The four muscles that compose this group are:
- Supraspinatus muscle , which comes from the supraspinous fossa of the scapula. This abducts the arm.
- Infraspinatus muscle , which comes from the infraspinous fossa of the scapula. This laterally rotates the arm.
- Teres minor muscle, comes from the lateral border of the scapula, and also laterally rotates the arm.
- Subscapularis muscle , originating from the subscapular fossa of the scapula. This muscle medially rotates the humerus.
This group of tendons can become torn, leading to pain and restricted movement of the arm.
A mnemonic to remember what muscles form the rotator cuff is SITS (supraspinatus, infraspinatus, teres minor, subscapularis) - someone with a rotator cuff injury sits out.
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