Nerve injuries to the upper limb

Question 1

In a radial nerve injury in the spiral groove, can the patient still extend their elbow? What muscle is paralysed?

Answer 1

Yes
Nerve to medial head triceps = before spiral groove
Nerve to lateral head = in spiral groove, prox. to fracture
Aconeus paralysed = minor role elbow ext.

Question 2

In what position will the wrist and fingers be when the wrist is pronated in a radial nerve injury in the spiral groove?

Answer 2

Flexed from paralysis of brachioradialis + all ext. muscles of wrist + fingers = wrist drop

Question 3

Where is sensory impairment in radial nerve injury in spiral groove?

Answer 3

Superficial branch radial nerve
(Post. Cutaneous nerve of arm branches above spiral groove, lower lat. + post cutaneous forearm = branch high in spiral groove = unaffected)

Question 4

In a high median nerve injury above the elbow (from supracondylar fracture), what muscles are paralysed?

Answer 4

Pronator teres/flexor carpi radialis/palmaris longus/flexor digitorum superficialis + any others supplied by median nerve

Question 5

In a high median nerve injury, what position will the patient be in?

Answer 5

Supinated forearm (as both supinators not median nerve = unopposed)
Weak wrist flexion, adduction from flexor carpi ulnaris (ulnar nerve)

Question 6

In a high median nerve injury, what happens to the fingers + thumb?

Answer 6

Opposition + palmar abduction thumb absent
FDS paralysed to 4 fingers, FDP to index + middle
Radial 2 lumbricals paralysed but MCPJs can still flex from interossei

Question 7

In a high median nerve injury, what happens when the patient attempts to make a fist?

Answer 7

Hand of Benediction
Ring + little fingers flex (FDP + lumbricals intact to these), but index + middle extended
Thumb ext. (EPL unopposed) + adducted (adductor pollicis unopposed)
Thumb lateral rotation from loss of opponens pollicis

Question 8

In long-standing high median nerve lesions, what deformity in the hand may result?

Answer 8

Ape hand deformity with thenar wasting
Thumb flexed @ MCPJ by FPB
No flexion @ IPJ thumb as FPL paralysed

Question 9

In a low median nerve injury, from a penetrating injury/compression in carpal tunnel, what muscles are paralysed?

Answer 9

LOAF (muscles @ common flexor origin intact)
Palmar cutaneous branch median nerve
Ape hand deformity (thumb adducted + externally rotated), thenar muscle wasting

Question 10

In an ulnar nerve injury of the wrist, what will the hand look like? What muscles are paralysed?

Answer 10

All muscles supplied by ulnar nerve

Claw hand = little/ring fingers hyperextended @ MCPJ (ext. digitorum unopposed), flexed @ IPJ (FDS + FDP unopposed)

Question 11

In an ulnar nerve injury, where is sensation lost? What happens to the interossei, hypothenar eminence and adductor pollicis?

Answer 11

Palmar aspect of ulnar 1 1/2 digits + dorsum of distal phalanges

Wasting of interossei = guttering between metacarpals
Atrophy adductor pollicis = loss of bulk 1st webspace
Atrophy hypothenar eminence

Question 12

In a high ulnar nerve injury, from compression in the cubital tunnel/medial epicondylar fracture, what muscles are paralysed?

Answer 12

Same as low ulnar nerve injury BUT also FCU, ulnar half FDP, loss sensation to dorsal + palmar cutaneous branches (+ palmar digital)

Question 13

In a high ulnar nerve injury, why is the clawing less pronounced?

Answer 13

FDP paralysed = no flexion @ distal IPJ of ring + little finger (only hyperextending MCPJ + flexion of PIPJ)
ULNAR PARADOX