Nerve Palsies

Question 1

Define Hilton’s Law?

Answer 1

Any nerve supplying a joint will also supply:

• The muscles moving that joint
• Skin over the insertion of those muscles

Question 2

Example of a nerve following Hilton’s Law?

Answer 2

Musculocutaneous nerve supplies the anterior capsule of the elbow, as well as:

• Muscles biceps, coracobrachialis and brachialis
• Skin over these muscle insertion

All via the lateral cutaneous nerve of the forearm (one of its terminal branches)

Question 3

Infant presents with the classic “Waiters Tip” position, what is this position?

Answer 3

Shoulder adducted and Internally rotated
Elbow extended and pronated
Wrist flexed

Question 4

What does the “Waiter’s Tip” position suggest pathologically?

Answer 4

Erb’s palsy, Traction of the brachial plexus (specifically C5/6 aka the superior trunk) e.g. during forceps delivery

Question 5

Patient presents with a clawed hand, what injury to the brachial plexus could cause this?

Answer 5

Klumpke’s Palsy, i.e. injury to the Inferior trunk (C8/T1). It affects the small hand muscles

Question 6

Other than Erb’s (sup trunk) & Klumpke’s (Inf Trunk) what other common nerve palsies affect the brachial plexus?

Answer 6

Total Brachial Plexus Palsy.

Affecting C5-T1

Question 7

Patient presents with a wasted deltoid and loss of sensation in their regimental badge area. They also mentioned having had a recent fracture of their arm?

Answer 7

Axillary nerve (C5/6) palsy, commonly associated with surgical neck fractures of the humerus and shoulder dislocation.

It supplies the deltoid, teres minor and regimental badge area

Question 8

What does the radial nerve arise from and supply?

Answer 8

C5-T1, arising from the post cord

Supplies:

• Triceps
• Brachioradialis
• ECRL & ECRB
• Finger extensors via PIN
• Posterior hand sensation via SRN

Question 9

How would compression or entrapment of the radial nerve present?

Answer 9

Depends on the level its injured at:

• Compress SRN at wrist –> lose sensation in hands (e.g. handcuffs)
• Compress PIN in forearm –> Lose finger extension
• Compress Radial in arm –> lose above + wrist extension
• Compress Radial in axilla –> Above + Elbow extension

Question 10

From where does the median nerve arise and what does it supply?

Answer 10

C5-T1, arises from medial & Lateral cords
Supplies:
- All forearm flexors except FCU & Medial half of FDP
- Sensation to radial 3.5 digits

Question 11

What condition comes with median nerve palsy?

Answer 11

Carpal Tunnel Syndrome

Question 12

What causes carpal tunnel syndrome? [5]

Answer 12

Developmental
Trauma (Distal radial fracture)
Ganglia, fibroma or lipoma swelling
Inflammatory - Gout, rheumatoid, TB or Amyloid
Metabolic - Pregnancy, mucopolysaccharides & Hypothyroidism

Question 13

How does carpal tunnel syndrome present?

Answer 13

Nocturnal pain & paraesthesia
Abductor Pollicis Brevis weakness
+ve Tinnels/Phalen’s Signs
Thenar wasting & ~scars + deformity

Question 14

Where does the ulnar nerve arise and what does it supply?

Answer 14

C8/T1, arising from medial cord

Supplies FCU & medial 1/2 of FDP
+ Intrinsic hand muscles except LOAF
Sensation to Ulnar 1.5 digits

Question 15

What are the LOAF Muscles?

Answer 15

The only intrinsic hand muscles not supplied by the ulna, they’re innervated by the median nerve:

• Lateral 2 Lumbricals
• Oppenens Pollicis
• Abductor Pollicis Brevis
• Flexor Pollicis Brevis

Question 16

What condition affects the ulnar nerve?

Answer 16

Cubital Tunnel Syndrome

Question 17

What is the cubital tunnel?

What is the ulnar paradox?

Answer 17

Tunnel between medial epicondyle & olecranon with the FCU fascia forming the roof. Contains the ulnar nerve

Distal lesion has worse clawing than a proximal lesion due to intact long flexors with distal lesion

Question 18

How does Cubital Tunnel Syndrome present?

Answer 18

Numbness on ulnar side of hand and fine dexterity loss
Hypothenar & 1st webspace wasting + guttering
Ulnar claw hand
+ve Froment’s Test (Tests Adductor pollicis)

Question 19

How does Cubital Tunnel syndrome cause a claw hand?

Answer 19

Ulnar claw hand involves hyperextension of the MCPJ and flexion of IPJs

Question 20

Patient presents with acute foot drop and pain under their knee?

Answer 20

FIbula fracture causing Common Peroneal Nerve Palsy

This presetns with Weakness in Dorsiflexion or “Foot Drop”

Question 21

Where does the Common Peroneal Nerve arise?

Answer 21

From the Sciatic nerve (L4-S3) which itself arises from the sacral plexus (L4-S4)

Question 22

Patient experiences altered sensation and pains in their lateral thigh, likely diagnosis?

Answer 22

Meralgia Parasthetica
The Lateral Cutaneous femoral Nerve (a branch of the lumbar plexus) is compressed as it travels under the lateral border of the inguinal ligament

This causes altered sensation and pain in the lateral thigh