Expansion
Supraspinatus abducts, Infraspinatus and Teres minor laterally rotate, Subscapularis medially rotates
Mnemonic
SITS, the four rotator cuff muscles in order around the joint:
- S - Supraspinatus, abducts the first 15 degrees
- I - Infraspinatus, externally rotates
- T - Teres minor, externally rotates
- S - Subscapularis, internally rotates
Subscapularis is the only one attaching to the lesser tubercle, and the only internal rotator; the other three insert on the greater tubercle.
Expansion
- Supraspinatus - initiates abduction
- Infraspinatus - lateral rotation
- Teres minor - lateral rotation
- Subscapularis - medial rotation
Beyond movement, the whole cuff works together to hold the humeral head in the glenoid and stabilise the shoulder.