Intrinsic Shoulder Muscles

Question 1

O: Supraspinous fossa of scapula
I: Greater tuberosity of humerus, capsule of shoulder joint
N: Suprascapular nerve
A: abducts arm, stabilizes shoulder joint

Answer 1

Supraspinatus

Question 2

O: Infraspinous fossa of scapula
I: Greater tuberosity of humerus, capsule of shoulder joint
N: Suprascapular nerve
A: Laterally rotates arm and stabilizes shoulder joint

Answer 2

Infraspinatus

Question 3

O: lower third of lateral border of scapula
I: medial lip of bicipital groove of humerus
N: Lower subscapular nerve
A: medially rotates and adducts arm and stabilizes shoulder joint

Answer 3

Teres major

Question 4

O: upper 2/3s of lateral border of scapula
I: greater tuberosity of humerus, capsule of shoulder joint
N: Axillary nerve
A: laterally rotates arm and stabilizes shoulder joint

Answer 4

Teres minor

Question 5

O: Subscapular fossa
I: Lesser tuberosity of humerus
N: Upper and lower subscapular nerves
A: Medially rotates arm and stabilizes shoulder joint

Answer 5

Subscapularis

Question 6

O: lateral 3rd of clavicle, acromion, spine of scapula
I: Middle of lateral surface of shaft of humerus
N: Axillary nerve
A: abducts arm, anterior fibers flex and medially rotate the arm, posterior fibers extend and laterally rotate the arm

Answer 6

Deltoid