OIAN: Posterior Scapula Muscles

Rotator Cuff Muscles

(SITS)

Supraspinatus

Infraspinatus

Teres Minor

Subscapularis

• these muscles function in order to stabilize the shoulder

• keeps the head of the humerus in contact w/ glenoid

• ABduction for first 15 degrees

• depress humeral head during elevation

Supraspinatus

O: supraspinous fossa of the scapula

I: superior facet of the greater tubercle of the humerus

A: initiate first 15 degrees of shoulder abduction

N: suprascapular nerve

Infraspinatus

O: infraspinous fossa of the scapula

I: middle facet of the greater tubercle of the humerus

A: externally rotate the shoulder

N: suprascapular nerve

Teres Minor

O: superior 2/3 of the lateral border of scapula

I: inferior facet of the greater tubercle of the humerus

A: externally rotate the shoulder

N: axillary nerve

Teres Major

O: inferior 1/3 of the lateral border of the scapula

I: medial lip of the intertubercular groove of the humerus

A: internally rotate and extend the shoulder

N: lower scapular nerve

Subscapularis

O: subscapular fossa

I: lesser tubercle of the humerus

A: internally rotate the shoulder

N: upper and lower subscapular nerves

Deltoid

O:

• Posterior fibers: inferior edge of the spine of the scapula

• Middle fibers: lateral acromion

• Anterior fibers: lateral 1/3 of the clavicle

I: deltoid tuberosity of the humerus

A:

• Posterior fibers: extend the shoulder

• Middle fibers: ABduct the shoulder

• Anterior fibers: flex the shoulder

N: axillary nerve

Triceps Brachii

O:

Long head: infraglenoid tubercle of the scapula

Lateral head: posterior, superior humerus, lateral to the radial groove

Medial head: posterior, inferior humerus,  medial  to the radial groove

I: olecranon process of the ulna

A:

Long head: Extend and adduct the shoulder, extend the elbow

Medial and Lateral heads: Extend the elbow 

N: radial nerve