Upper limb nerve injuries

Question 1

Raidal nerve injury in spiral groove of humerus

Can elbow extension still occur?

What position will wrist be when pronated and why?

Likely distribution of sensory impairement?

Answer 1

• Yes. Nerve supply to long and m heads of tricepsgiven off prior to radial nerve entry into spiral groove.
• Flexed. Paralysis of all extensor muscles of wrist and fingers + unopposed flexor muscle and gravity > wrist drop
• superificial branch of radial nerve distribution

Question 2

Median nerve injury at arm

Which muscles will be affected?

How will the hand be presented?

What happens when patients attemp to make a fist?

What will happen to thumb?

What are the complications?

Answer 2

• most of anterior forearm muscles except FCU and ulnar half of FDP
• forearm supinated, wrist adduction
• ring and little finger will flex normally - FDP and lumbricals intact to these digits, Index and middle finger remain extended (hand of benediction)
• IPJ and MCPJ extended - unopposed action of EPL, thumb adducted - x opponens pollicis
• Ape hand deformity + thenar wasting

Question 3

Median nerve injury at wrist

What causes it?

Which muscles will be affected?

What will the resulting deformity be? Describe it.

Answer 3

• carpal tunnel syndrome
• lumbricals of index & middle finger, opponens pollicis, APB, FPB (LOAF)
• Ape hand deformity. Thumb adducted, externally rotated, thenar eminence flattened.

Question 4

Ulnar nerve injury at wrist

Which muscles will be affected?

What is the complication?Describe it

Why does distal ulnar claw happen?

Answer 4

• hypothenar eminence, AdP, FPB, interossei, lumbricals to ring and middle finger, palmaris brevis
• Distal ulnar claw. Ring and middle finger hyperextended at MCPJ and flexed at both IPJs
• 3rd and 4th lumbrical muscles supplied by ulnar nerve - paralysed. Lumbricals flex at MCPJ and extend at IPJs. In ulnar claw, MCPJ hyperextend due to unopposed extension from extensor digitorum. IPJs flex due to unopposed flexion from FDS & FDP

Question 5

Ulnar nerve injury at elbow

What causes it?

Which muscle will be affected?

What is the complication and describe it

What is the ulnar paradox?

Answer 5

• medial epicondylar fracture, cubital tunnel compression
• ulnar half of FDP
• high ulnar claw. hyperextension at MCPJ and flexion at PIPJ. Less evident claw produced.
• a more proximal injury is expected to produce a more pronounced deformity but the opposite occurs