The Back

Question 1

What are the superficial, extrinsic muscles of the back?

Answer 1

Trapezius and latissimus dorsi

Question 2

What are the deep extrinsic muscles of the back?

Answer 2

Levator scapulae and rhomboid

Question 3

What are the scapulo-humeral muscles in the back?

Answer 3

Deltoid, teres major and the four rotator cuff muscles

Question 4

What affixes the trapezius to the spine?

Answer 4

Ligamentum nuchae

Question 5

What are the three bundles of fibres in the trapezius and what is their function?

Answer 5

Superior - clavicle (elevates)
Middle - inner lip of the acromium (retracts)
Inferior - spine of the scapula (pulls inferiorly)

Question 6

Innervation of the trapezius

Answer 6

Accessory nerve (cranial nerve XI)

Question 7

Function of the trapezius

Answer 7

Superior and inferior bundles act together to rotate the scapula upwards so the glenoid cavity can move up and out.
The arm can be abducted to 90 degrees before the trapezius is required.

Question 8

Describe how you would clinically test the accessory nerve

Answer 8

Get the patient to shrug their shoulders against resistance.

Question 9

Function of latissimus dorsi

Answer 9

Adduction of the arm, extends at the shoulder joint.
Medial rotation (arm inwards)

Question 10

Innervation of latissimus dorsi

Answer 10

Thoracodorsal nerve from the posterior cord of the brachial plexus

Question 11

Function of the rhomboid

Answer 11

Retraction and rotation of the scapula inferiorly so the glenoid cavity points upwards.

Question 12

Innervation of the rhomboid

Answer 12

Dorsal scapular nerve from the C5 root of the brachial plexus

Question 13

Function of the levator scapulae

Answer 13

Elevates and rotates the scapula

Question 14

Innervation of the levator scapulae

Answer 14

Dorsal scapular nerve and cervical nerves

Question 15

Function of the teres major

Answer 15

Adduction and medial rotation of the arm

Question 16

Innervation of the teres major

Answer 16

Lower scapular nerve