Lecture 9: Neurovasculature of the Upper Limb

Question 1

What are the roots of the brachial plexus?

Answer 1

convergence of ventral primary rami of spinal nerves C5-T1

at either end there may be some contribution from adjacent ventral rami, ie. C4 or T2

Question 2

What does the initial combination of roots form?

Answer 2

the trunks

Question 3

What does each trunk give off?

Answer 3

each gives off anterior and posterior divisions

Question 4

What are anterior divisions?

Answer 4

motor and sensory innervation for anterior of limb

Question 5

What are posterior divisions?

Answer 5

motor and sensory for posterior of limb

Question 6

What do the divisions join to form?

Answer 6

cords
anterior divisions of the upper and middle trunks form the lateral cord
anterior division of the lower trunk forms the medial cord
all posterior divisions converge to form the posterior cord

Question 7

What form the roots of the plexus?

Answer 7

ventral primary rami from individual spinal nerves

Question 8

What does injury to the ulnar nerve result in?

Answer 8

paresthesia of the ulnar 1.5 finger margins
if prolonged intrinsic muscle wasting -> best observed in posterior tissue mass between thumb and index finger
hypothenar muscle wasting may also be evident

Question 9

What is the hand posture of someone who has experienced an injury to the ulnar nerve?

Answer 9

hand posture most likely IP flexion with MCP extension i.e. claw hand

Question 10

What does injury to the median nerve due to carpal tunnel syndrome result in?

Answer 10

paraesthesia of radial 2.5 finger margins

if prolonged: thenar muscle wasting

Question 11

What does injury to the median nerve if impaction is proximal result in?

Answer 11

negative “OK sign”

Question 12

What does injury to the radial nerve result in?

Answer 12

loss/weakness of elbow, wrist and finger extensors -> wrist drop and perhaps elbow flexion

Question 13

Through which veins does blood flow out of the tissues of the hand?

Answer 13

tissue -> dorsal digital vv. -> dorsal metacarpal vv. -> dorsal venous arch -> major superficial vv.

Question 14

Where does the basilic vein run?

Answer 14

starts on the ulnar (little finger) side of the hand and runs up the arm

Question 15

Where does the cephalic vein run?

Answer 15

starts on the radial (thumb) side of the hand and runs up the arm

Question 16

Why are veins superficial to muscle?

Answer 16

if veins were amongst the muscle this would be a problem because the swelling and contracting muscle would compress the veins and stop blood return

Question 17

What is the vena comitans?

Answer 17

an alternative to an extensive deep venous network

Question 18

Where does the vena comitans travel?

Answer 18

alongside the arterial supply of the limb

Question 19

What is the role of the vena comitans?

Answer 19

drain both the thick walls of larger arteries, and the surrounding tissues

Question 20

Through which arteries does blood flow from the arm down to the hand?

Answer 20

axillary a. -> brachial a. which branches off into the radial a. and the ulnar a. -> superficial and deep palmar arches