Nerve and blood supply to the upper limbs

Question 1

Broadly speaking what is the “stem” artery of the upper limb? Where does it originate?

Answer 1

Subclavian artery

• Right from the brachiocephalic trunk
• Left from arch of the aorta

Question 2

Describe the trajectory of the “stem” artery of the upper limb. State the way in which it divides and the anatomical structure relevant to this

Answer 2

Passes through scalene triangle (over the first rib)

Divided into 3 parts by scalenus anterior

• 1st: Medial to muscle
• 2nd: Behind muscle
• 3rd: Lateral to muscle

Question 3

State the branches of the subclavian artery

Answer 3

1st

• vertebral artery
• thyrocervical trunk (to thyroid, cervical, scapular) it contributes to scapular anastomosis

2nd

3rd
- dorsal scapular artery (from 2nd/3rd part) it contributes to scapular anastomosis

Question 4

Where does the subclavian artery end?

Wheres does the axillary artery end?

Answer 4

Ends as it crosses the outer border of first rib to become the axillary artery

Ends at lower border of teres major to become the brachial artery

Question 5

Describe the divisions of the axillary artery

Answer 5

Divided into three parts by pectoralis minor
1st- medial to muscle
2nd- behind muscle
3rd- lateral to muscle

1st/2nd parts closely associated with the brachial plexus

Question 6

What is the clinical relevance of the surgical neck of the humerus?

Answer 6

• Risk of fracture, trauma to ant/post circumflex humeral arteries (to neck/shaft of humerus)

Question 7

Which division of the axillary artery gives rise to the subcapsular artery and the ant/post circumflex humeral arteries? Where do these vessels supply?

Answer 7

Subcapsular from the 3rd division supplies scapular anastomosis

Ant/post circumflex humeral arteries supply neck/shaft of humerus

Question 8

Describe the brachial artery

consider its location, function and divisions

Answer 8

• Superficial throughout arm
• Supplies flexors
• Large branch = profunda brachii artery (supplies extensors)
• Contributes to anastomosis around elbow
• Divides in cubital fossa into radial and ulnar arteries

Question 9

Describe the profunda brachii artery

How is it clinically relevant?

Answer 9

• It accompanies radial nerve in spiral groove

- Fracture to humerus can result in trauma to profunda brachii artery

Question 10

Describe the radial artery

How does it end in the hand?

Answer 10

• Lateral side of forearm (in anatomical position)
• Smaller of the two terminal branches
• Covered by brachioradialis muscle
• Forms deep palmer arch (below flexor tendons)
• At wrist it winds around to dorsum of hand
• Through anatomical snuff box and pierces first dorsal interosseous muscle

Question 11

Describe the ulnar artery

How does it end in the hand?

Answer 11

• medial side of forearm
• Covered by flexor carpi ulnaris muscle
• Deep branch: common interosseous artery
• Forms superficial palmar arch
• Branch to deep palmer arch to superficial palmer arch (above flexor tendons)
• Gives rise to palmer digital arteries

Question 12

Describe the venous return of the upper limb

Answer 12

• Variable
• Drains into axillary vein into subclavian vein in the deltopectoral groove

DEEP VEINS: paired veins, venae comitantes

SUPERFICIAL VEINS: (from dorsal venous arch, posteriorly)

• cephalic: lateral forearm
• basilic: medial forearm

Question 13

Which vein connects the basilic and cephalic vein

Answer 13

Medial cubital vein

Question 14

Describe the lymphatic drainage of the upper limb

Answer 14

Lymph drains to axillary nodes from

• deltopectoral node (cephalic vein)
• cubital nodes (basilic vein)

Question 15

What is the brachial plexus?

How is it divided?

Answer 15

• Nerve supply to the upper limb
• It carries motor, sensory and sympathetic axons
• Produces mixed nerves (contains axons from multiple spinal nerves which is important in supply of large muscle groups)
• Divided into roots, trunks, division, cords and terminal branches (=mixed nerves)

Question 16

State the roots of the brachial plexus AND the movements facilitated by different by the motor axons within each root

Answer 16

Roots are ventral primary rami of C5-T1

C5- Shoulder abduction and adduction
C6/C7- Elbow flexion and extension
C7/C8- Wrist flexion and extension
C8/T1- Movement of the digits

Question 17

Roots of the brachial plexus form trunks. Where doe these trunks pass through?

Answer 17

Scalene triangle

Trunk- superior + middle + inferior

Question 18

The trunks of the brachial plexus divide into anterior and posterior division. Describe these

Answer 18

ANTERIOR
- Axons to flexor compartments (forms lateral and medial cords)

POSTERIOR
- Axons to extensor compartments (forms posterior cord)

Question 19

The cords of the brachial plexus are found…..

They are named in relation to which artery?

Answer 19

Under pectoralis minor

Cords named in relation to axillary artery (i.e. posterior cord lies behind the axillary artery)

Question 20

How does the lateral cord terminate?

Answer 20

Terminates as musculocutaneous nerve and lateral part of median nerve

• The musculocutaneous nerve provides motor supply to the anterior arm (innervates biceps brachii muscle) and sensory to the lateral forearm (gives rise to lateral cutaneous nerve).

Question 21

How does the medial cord terminate?

Answer 21

Terminates as medial part of median nerve and ulnar nerve

Question 22

State the function of the median nerve

Answer 22

• Motor to anterior forearm and lateral hand

- Sensory to lateral palm hand, d1,2,3 + half d4

Question 23

State the function of the ulnar nerve

Answer 23

• Motor to medial side anterior forearm (flexor carpi ulnaris muscle) and hand
• Sensory to medial hand + half d4, d5

Question 24

How does the posterior cord terminate?

Answer 24

Terminates as radial and axillary nerve

Question 25

State the function of the radial nerve

Answer 25

MOTOR
- Posterior arm (triceps) and posterior forearm (supinator muscle + brachioradialis muscle)

SENSORY
- Posterior arm and posterior forearm + lateral dorsum hand

Question 26

State the function of the axillary nerve

Answer 26

MOTOR
- Deltoid and teres minor

SENSORY
- Badge area of arm

Question 27

What is a dermatome

What is the clinical relevance?

Answer 27

An individual area of skin innervated by a single spinal nerve

• established during development
• lots of overlap/variation

Altered sensation in the region of a dermatome indicates damage to specific spinal nerve of spinal cord segment (i.e. proximal nerve injury)

Question 28

How does the dermatome map differ to cutaneous innervation by terminal branches?

What is the clinical relevance?

Answer 28

Terminal branches contain axons from multiple spinal nerve

Altered sensation in one of the above areas indicates damage to a more distal nerve segment (i.e. distal nerve injury)