19: Nerve Injuries/Palsies in the Limbs

Question 1

give examples of injuries that could cause brachial plexus lesions

Answer 1

• downward traction (e.g. fall on side of neck) > C5,6 damage (deltoid & shoulder muscles, brachialis & biceps)
• upward traction (e.g., breech delivery) > T1 damage (intrinsice muscles)

Question 2

what is the name of this

Answer 2

Erb’s palsy

Question 3

what is the name of this palsy?

Answer 3

Klumpke’s palsy

Question 4

which nerve of the brachial plexus wraps around the surgical neck of humerus?

Answer 4

axillary nerve (C5,6)

Question 5

which nerve innervates the deltoid, teres minor and skin over lateral arm?

Answer 5

axillary nerve (C5,6)

Question 6

give a couple of examples of injuries that can cause axillary nerve palsy (C5,6)

Answer 6

Question 7

the radial nerve divides into which branches?

Answer 7

• posterior interosseous nerve (motor, deep branch) and
• superficial radial nerve (sensory) branches

Question 8

give a couple mechanisms of radial nerve palsy

Answer 8

Question 9

what will a radial nerve palsy in the axillary region cause?

Answer 9

• loss of elbow extension
• wrist extension
• sensory changes in forearm and hand

Question 10

what will a radial nerve palsy in the arm (not forearm) cause?

Answer 10

• loss of wrist extension and sensory loss

Question 11

what will a radial nerve palsy in the forearm region cause?

Answer 11

loss of finger extension (posterior interosseous nerve PIN)

Question 12

what will radial nerve palsy in the wrist region cause?

Answer 12

loss of sensation (superficial radial nerve SRN) e.g. handcuffs

Question 13

list the causes of carpal tunnel syndrome (median nerve compression)

Answer 13

• developmental
• trauma > distal radius fracture
• swellings e.g. ganglion, fibroma, lipoma
• inflammatory e.g. rheumatoid, gout, TB, amyloid
• metabolic e.g. pregnancy, mucopolysaccharidoses, hypothyroidism

Question 14

carpal tunnel syndrome clinical features

Answer 14

• nocturnal pain and paraesthesia in part or all of the median nerve distribution
• wasting of the thenar muscles
• experience symptoms when performing Tinnel’s and Phalen’s test
• reduced abductor pollicis brevis power

Question 15

what does the ulnar nerve innervate?

Answer 15

• supplies medial hald of flexor digitorum profundus, flexor carpi ulnaris and all intrinsic muscles in the hand except from FOAL: flexor pollicis brevis, opponens pollicis, abductor pollicis brevis, lateral two lumbricals
• sensation to ulnar 1.5 digits.

Question 16

which intrinsic muscles of the hand are innervated by the median nerve?

Answer 16

FOAL: flexor pollicis brevis, opponens pollicis, abductor pollicis brevis, lateral two lumbricals

Question 17

what is the 2nd most common nerve entrapment syndrome?

Answer 17

cubital tunnel syndrome

Question 18

ulnar nerve palsy clinical presentation

Answer 18

• patient has numbness on ulnar side of hand and difficult with fine tasks
• muscle wasting: 1st webspace (often most marked), guttering, hypothenar wasting

Question 19

what test can be used to assess an ulnar nerve palsy?

Answer 19

Froment’s test
- If ulnar nerve not working, the patient will cheat and use FPL instead of adductor pollicis

Question 20

what does the lateral femoral cutaneous nerve (L2,3) innervate?

Answer 20

• purely sensory to lateral aspect of thigh

Question 21

meralgia paraesthetic is caused by palsy to which nerve?

Answer 21

lateral femoral cutaneous nerve (L2,3)

Question 22

what is the largest nerve in the body called?

Answer 22

Sciatic nerve
- main branch of sacral plexus; broad and flat with accompanying artery

Question 23

what are the roots of the sciatic nerve?

Answer 23

L4-S3

Question 24

what does palsy to the common fibular nerve (L4-S2) cause?

Answer 24

• deficit causes foot drop and slapping gait
• nerve passes around lateral aspect of neck of fibula

Question 25

what is the most commonly injured nerve in the lower limb?

Answer 25

common fibular nerve L4-S2