Intrinsic Muscles of the Shoulder

Question 1

Origin of the supraspinatus

Answer 1

medial 2/3 of supra spinous fossa of scapula

Question 2

Insertion of supraspinatus

Answer 2

uppermost facet of greater tuberosity of humerus

(its tendon passes deep to the coracoacromial arch and separated from it by the subacromial bursa)

Question 3

Nerve supply of supraspinatus

Answer 3

Suprascapular nerve

Question 4

Actions of supraspinatus

Answer 4

1. abduction of the arm (from 0 to 15 degrees)
2. helps keep the head of the humerus in the glenoid cavity during the action of other muscles

Question 5

Origin of infraspinatus (2)

Answer 5

1. medial 2/3 of infraspinous fossa
2. from fascia covering the muscle

Question 6

Insertion of Infraspinatus

Answer 6

into the middle facet of greater tuberosity of humerus

Question 7

Nerve supply of infraspinatus

Answer 7

Suprascapular nerve

Question 8

Actions of infraspinatus

Answer 8

1. adduction of the arm
2. lateral rotation of the arm
3. steadies shoulder joint

Question 9

Origin of teres minor

Answer 9

Upper 2/3 of dorsal aspect of lateral border of scapula

Question 10

Insertion of teres minor

Answer 10

lowermost facet on the back of greater tuberosity of humerus

Question 11

Nerve supply of teres minor

Answer 11

axillary nerve (circumflex)

Question 12

Actions of teres minor

Answer 12

1. Lateral rotation of the arm
2. Adduction of the arm
3. Steadies shoulder joint

Question 13

Origin of teres major

Answer 13

an oval area on the lower 1/3 of dorsal aspect of lateral border of scapula

Question 14

Insertion of teres major

Answer 14

into medial lip of bicipital groove of humerus

Question 15

Nerve supply of teres major

Answer 15

lower subscapular nerve

Question 16

Actions of teres major

Answer 16

1. Adduction of the arm
2. Medial rotation of the arm
3. Extension of the arm

Question 17

Origin of subscapularis

Answer 17

Medial 2/3 of subscapular fossa of scapula

Question 18

Insertion of subscapularis

Answer 18

into lesser tuberosity of humerus and extending for 1/2 an inch on the shaft

Question 19

Nerve supply of subscapularis

Answer 19

Upper and lower subscapular nerves

Question 20

Actions of subscapularis

Answer 20

1. Adduction of the arm
2. Medial rotation of arm
3. Steadies shoulder joint