Intrinsic muscles of the shoulder

Question 1

What is the generic name for the intrinsic muscles and where are they found?

Answer 1

Scapulohumeral group

Scapula/clavicle + insert to humerus

Question 2

What are the 6 intrinsic muscles?

Answer 2

Deltoid, teres major, 4 rotator cuff

Question 3

Describe the origin, insertion, innervation + action of teres major

Answer 3

Post. scapula @ inferior angle
Medial lip of intertubercular sulcus
Lower subscapular nerve
Adducts arm @ shoulder, medially rotates arm

Question 4

What is the collective function of the rotator cuff muscles?

Answer 4

Pull humeral head into glenoid fossa

Question 5

Describe the origin, insertion, innervation + action of supraspinatus

Answer 5

Supraspinous fossa of scapula
Greater tubercle of humerus
Suprascapular nerve
Abducts arm 0-15 degrees (assists deltoid 15-90)

Question 6

Describe the origin, insertion, innervation + action of infraspinatous

Answer 6

Infraspinous fossa of scapula
Greater tubercle of humerus
Suprascapular nerve
Laterally rotates arm

Question 7

Describe the origin, insertion, innervation + action of subscapularis

Answer 7

Subscapular fossa
Lesser tubercle
Upper + lower subscapular nerves
Medially rotates arm

Question 8

Describe the origin, insertion, innervation + action of teres minor

Answer 8

Posterior scapula
Greater tubercle
Axillary nerve
Laterally rotates arm

Question 9

What are the 4 rotator cuff muscles?

Answer 9

SITS
Supraspinatus
Infraspinatus
Subscapularis
Teres minor