Nerve palsies in limbs

Question 1

Where is the axillary nerve at risk of injury?

Answer 1

At surgical neck of humerus

Question 2

What may cause axillary nerve injury?

Answer 2

Fracture of humeral neck, shoulder dislocation, Saturday night palsy (pressure on the posterior cord of brachial plexus)

Question 3

What motor and sensory deficits would you see in axillary nerve damage?

Answer 3

Motor deficit – loss of shoulder abduction (deltoid)

Sensory deficit – regimental badge area (skin over lateral arm)

Question 4

Where is the radial nerve at risk of injury?

Answer 4

Spiral groove of humerus + lateral intermuscular septum (+ posterior interosseous branch at the radial neck)

Question 5

What may cause injury to the radial nerve?

Answer 5

Fracture of the humeral shaft, Saturday night palsy (pressure on posterior cord of the brachial plexus), exposure of proximal radius

Question 6

What motor and sensory deficits may you see in radial nerve injury?

Answer 6

Motor – wrist drop (extensor muscles affected)

Sensory – 1st web space dorsally

Question 7

Where is the median nerve at risk of getting injured?

Answer 7

Volar aspect of the wrist (+ cubital fossa)

Question 8

What is median nerve injury a complication of

Answer 8

Carpal tunnel syndrome, wrist lacerations (+supracondylar fractions, Struthers’s ligament)

Question 9

What motor and sensory deficits would be a result of median nerve injury?

Answer 9

Motor – thenar wasting (Monkey’s hand), pointing finger

Sensory deficit – volar aspect of thumb (palm)

Question 10

Where is the ulnar nerve at risk of getting injured?

Answer 10

Behind medial epicondyle of the humerus (&wrist, canal of Guyon)

Question 11

What is ulnar nerve injury a complication of?

Answer 11

Fracture of the humeral epicondyles (and wrist lacerations)

Question 12

What motor and sensory deficits would we see in ulnar nerve injury?

Answer 12

Motor deficit – claw hand (hyperextension MCPJ, flexion at IPJ’s), hypothenar + 1st dorsal interosseous wasting (may be visible)
Sensory deficit – little finger

Question 13

Describe femoral nerve supply and its termination

Answer 13

L2-L4, supplies quadriceps in thigh (anterior). Terminates in a long fine sensory branch (saphenous nerve)

Question 14

Describe lateral cutaneous femoral nerve supply and effects of its injury

Answer 14

Purely sensory to lateral aspect of thigh. Compression causes “meralgia paraesthetica” (tingling, numbness, burning pain in outer thigh)

Question 15

Describe sciatic nerve supply and what can cause its injury

Answer 15

Supplies hamstring muscle in thigh (posterior) and part of adductor magnus, and all lower leg and foot muscles via terminal branches (tibial and common fibular nerves). At risk from posterior dislocation of hip, IM injections and during surgery (its division is devastating).

Question 16

Describe common fibular nerve and effect of its injury

Answer 16

Passes around lateral aspect of neck of fibula (at risk! – deficit causes foot drop and slapping gait – most commonly injured nerve in lower limb). Has a communication branch to sural nerve and divides into superficial and deep fibular nerves.

Question 17

Describe carpal tunnel syndrome and its effects

Answer 17

Caused by pressure on median nerve as it passes through the wrist (through the carpal tunnel). Causes a combination of paraesthesia, numbness, pain (usually gets worse at night along w/ other symptoms). Usually affects the thumb, index, and middle fingers, sometimes extending to medial aspect of fourth finger (median nerve distribution). Can also cause wasting of thenar muscles causing weakness of grip (longstanding).

Question 18

What may be causative factors for carpal tunnel syndrome

Answer 18

Pressure may result from continuous repetitive movements of the hand, such as keyboarding, or any conditions causing local swelling. Potential causative factors: developmental, trauma (distal radius fracture), swellings (ganglion, fibroma, lipoma), Inflammatory (rheumatoid, gout, TB, amyloid), metabolic (pregnancy, mucopolysaccharidoses, hypothyroidism).

Question 19

What may you do on examination and investigation of carpal tunnel syndrome

Answer 19

LOOK for thenar wasting, prev scars, deformity (prev fracture). FEEL – test sensation. MOVE – APB power. SPECIAL TESTS – Tinnels (percussing over nerve) & Phalens (pushing dorsal aspects of hands together). Surgical repair – CT release.

Question 20

Describe what cubital tunnel syndrome is

Answer 20

2nd most common nerve entrapment, is between medial epicondyle + olecranon, w/ fascial bands from FCU as roof. Condition involves pressure or stretching of the ulnar nerve (‘funny bone’ nerve), can cause numbness or tingling in the ring and small fingers (ulnar side of hand), pain in the forearm, and/or weakness in hand, difficulty with fine tasks.