Muscles of the Shoulder

Question 1

What are the superficial extrinsic shoulder muscles?

Answer 1

Latissimus Dorsi

Trapezius

Question 2

What nerve causes motor innervation of the Trapezius muscle?

Answer 2

The accessory nerve

Question 3

What causes sensory innervation of the Trapezius muscle?

Answer 3

C3 and C4 spinal roots

Question 4

What is the main action of the upper fibres of the Trapezius?

Answer 4

Elevate the scapula and rotate it during abduction of the shoulder

Question 5

What is the main action of the middle fibres of the Trapezius?

Answer 5

Retract the Scapula

Question 6

What is the main action of the lower fibres of the Trapezius?

Answer 6

Pull the Scapula inferiorly

Question 7

How can you test the function of the accessory nerve?

Answer 7

See how the Trapezius muscle functions by asking the patient to elevate the shoulder against resistance.

Question 8

What nerve innervates Latissimus Dorsi?

Answer 8

The thoracodorsal nerve

Question 9

What are the main actions of Latissimus Dorsi?

Answer 9

Extension of the arm at the shoulder
Adduction at the shoulder
Medial rotation of the arm

Question 10

What are the deep extrinsic muscles of the shoulder?

Answer 10

Levator scapulae

Rhomboids

Question 11

What nerve innervates the Levator scapulae?

Answer 11

The Dorsal scapular nerve

Question 12

What are the main actions of the Levator scapulae?

Answer 12

Elevates scapula

Rotates scapula to tilt the Glenohumeral joint inferiorly

Question 13

What are the two Rhomboid muscles?

Answer 13

Rhomboid major

Rhomboid minor

Question 14

What innervates the Rhomboid muscles?

Answer 14

The Dorsal scapular nerve

Question 15

What are the actions of the Rhomboid muscles?

Answer 15

Retracts the scapula
Fix scapula to thoracic wall
Rotates scapula to tilt the Glenohumeral joint inferiorly

Question 16

What are the Scapulohumeral muscles?

Answer 16

Deltoid

Teres major

Question 17

What innervates the Deltoid?

Answer 17

The axillary nerve

Question 18

What is the main action of the anterior fibres of the Deltoid?

Answer 18

Flex the arm at the shoulder

Question 19

What is the main action of the posterior fibres of the Deltoid?

Answer 19

Extend the arm at the shoulder

Question 20

What is the main function of the middle fibres of the Deltoid?

Answer 20

Major abductors of the arm, from 15 degrees onwards

Question 21

What innervates Teres major?

Answer 21

The lower subscapular nerve

Question 22

What are the main actions of the Teres major?

Answer 22

Adductors the shoulder

Medially rotates the arm

Question 23

What are the 4 rotator cuff muscles?

Answer 23

Supraspinatus
Infraspinatus
Teres minor
Subscapularis

Question 24

What is main function of the rotator cuff muscles?

Answer 24

Add stability to the glenohumeral joint

Question 25

What innervates the Supraspinatus muscles?

Answer 25

Suprascapular nerve

Question 26

What is the main action of the Supraspinatus muscle?

Answer 26

First 15 degrees abduction of the arm | Aids the Deltoid for the rest

Question 27

What innervates the Infraspinous muscle?

Answer 27

Suprascapular nerve

Question 28

What is the main action of the Infraspinous muscle?

Answer 28

Lateral rotation of the arm

Question 29

What innervates the Subscapularis muscle?

Answer 29

Upper and lower Subscapular nerve

Question 30

What is the main action of the Subscapularis muscle?

Answer 30

Medially rotates the arm

Question 31

What innervates Teres minor?

Answer 31

The axillary nerve

Question 32

What is the main action of Teres minor?

Answer 32

Lateral rotation of the arm

Question 33

What is a sign of rotator cuff tendonitis?

Answer 33

Painful arc syndrome

Question 34

What is painful arc syndrome?

Answer 34

Pain in the middle of abduction of the arm due to the affected area coming into contact with the acromion

Question 35

What is the pathology of rotator cuff tendonitis?

Answer 35

Degenerative changes in the subacromial bursa and supraspinatus tendon due to repetitive use.