Rotator Cuff Muscles: Location & Function

Infraspinatus & Teres Minor

LATERAL rotation w/ posterior deltoid (& adduction)

Supraspinatus

1 ABDUCTION 2 STABILIZATION of humerus' head in glenoid cavity * assists deltoid - main abduction agonist for first 10-15 degrees - until deltoid action. * resists gravitational pull by weight of upper limb. * presses humerus head medially against glenoid fossa * moves ARM at shoulder joint

Teres Minor Function

1 LATERAL ROTATION 2 ADDUCTION 3 STABILIZATION of humerus' head in glenoid cavity * Infraspinatus & posterior deltoid assist w/ lateral rotation *laterally rotates, extends, and adducts arm * Moves ARM at shoulder joint

Subscapularis

1 MEDIAL ROTATION 2 STABILIZATION of humerus' head in glenoid cavity * draws humerus forward and downward to prevent displacement * pectoralis major assists w/ rotating * moves ARM at shoulder joint

Stabilizes Humerus

ALL = Infraspinatus, Subscapularis, Supraspinatus, Teres Minor

Lateral Rotation of Arm

Infraspinatus, Teres Minor

Acronym SITS

SIT w/ Subscapularis muscle, which unlike the other rotator cuff muscles, attaches to the lesser tubercle of the humerus.

Medially rotates arm

Subscapularis

Abducts arm

Supraspinatus

Acronym SIT

Supraspinatus, Infraspinatus Teres minor 3 rotator cuff muscles (superior to inferior) that insert into greater tubercle of the humerus

Infraspinatus

- Infraspinous fossa of scapula - Greater tubercle of humerus * Superficial muscle * POSTERIOR trunk * Inferior to spine of scapula * Partially covered by deltoid

Teres minor

- Lateral border of scapula - Greater tubercle of humerous * Superficial muscle * POSTERIOR TRUNK * Inferior to infraspinatus * Partially covered by deltoid

Subscapularis

- Subscapular fossa - LESSER tubercle of humerus * Deep muscle * Ventral side of scapula * ANTERIOR tunk * Front of capsule of shoulder-joint. * Large triangular muscle

Supraspinatus

- Supraspinous fossa - Greater tubercle of humerus * Deep Muscle * POSTERIOR TRUNK * Superior to spine of scapula. * Completely covered by deltoid.

Infraspinatus

1 LATERAL ROTATION 2 STABILIZATION of humerus' head in glenoid cavity * assists teres minor w/ lateral rotation & adduction * moves ARM at shoulder joint

Adducts arm

Teres Minor

Rotator Cuff Injury

tear in the tendon of any of the rotator cuff muscles, most often the the supraspinatus. caused by strenuous circumduction of the arm shoulder dislocation hard falls or blows to the shoulder or repetitive use of the arm in a position above horizontal. common in baseball pitchers

Rotator Cuff Function

flexion, extension, abduction, adduction, rotation, and circumduction