Intrinsic Muscles of the Shoulder

Question 1

Which muscles make up the intrinsic muscles of the shoulder

Answer 1

Deltoid
Teres major
Rotator cuff muscles

Question 2

What are the rotator cuff muscles

Answer 2

Supraspinatus
Infraspinatus
Subscapularis
Teres minor

Question 3

Where does deltoid originate

Answer 3

Scapula

Clavicle

Question 4

Where does deltoid insert

Answer 4

Deltoid tuberosity on the lateral surface of the humerus

Question 5

Which nerves innervate deltoid

Answer 5

Axillary nerve

Question 6

What is the action of the anterior fibres of deltoid

Answer 6

Flex the arm at the shoulder

Question 7

What is the action of the posterior fibres of deltoid

Answer 7

Extend the arm at the shoulder

Question 8

What is the action of the middle fibres of deltoid

Answer 8

Major abductor of the arm

Question 9

What is the quadrangular space

Answer 9

The gap that the axillary nerve and posterior circumflex humeral artery pass through to reach the posterior scapula region

Question 10

What forms the inferior border of the quadrangular space

Answer 10

Teres major

Question 11

Where does teres major originate

Answer 11

Posterior surface of the inferior angle of scapula

Question 12

Where does teres major insert

Answer 12

Medial lip of the intertubercular groove of humerus

Question 13

Which nerves innervate teres major

Answer 13

Lower subscapular nerve

Question 14

What is the action of teres maor

Answer 14

Adducts at the shoulder

Internal rotation of the arm

Question 15

What is the collective function of the rotator cuff muscles

Answer 15

Pulls humeral head into the glenoid fossa providing stability to the glenohumeral joint

Question 16

Where does supraspinatus originate

Answer 16

Supraspinous fossa of the scapula

Question 17

Where does supraspinatus insert

Answer 17

Greater tubercle of the humerus

Question 18

Which nerve innervates supraspinatus

Answer 18

Suprascapular nerve

Question 19

What is the action of supraspinatus

Answer 19

Abducts the arm 0-15 degrees

Assists deltoid for 15-90 degrees abduction

Question 20

Where does the infraspinatus originate

Answer 20

Infraspinous fossa of the scapula

Question 21

Where does infraspinatus insert

Answer 21

Greater tubercle of the humerus

Question 22

Which nerve innervates infraspinatus

Answer 22

Suprascapular nerve

Question 23

What is the action of infraspinatus

Answer 23

Externally rotates the arm

Question 24

Where does subscapularis originate

Answer 24

Subscapular fossa on the costal surface of the scapula

Question 25

Where does subscapularis insert

Answer 25

Lesser tubercle of the humerus

Question 26

Which nerves innervate subscapularis

Answer 26

Upper subscapular nerves

Lower subscapular nerves

Question 27

What is the action of subscapularis

Answer 27

Internally rotates the arm

Question 28

Where does teres minor originate

Answer 28

Posterior surface of the scapula, adjacent to its lateral border

Question 29

Where does teres minor insert

Answer 29

Greater tubercle of the humerus

Question 30

Which nerve innervates teres minor

Answer 30

Axillary nerve

Question 31

What is the action of teres minor

Answer 31

Externally rotates the arm

Question 32

Which rotator cuff muscle is most commonly affected with tendonitis

Answer 32

Supraspinatus - during abduction it rubs against the coraco-acromial arch