Nerve Palsies

Question 1

Where can a nerve be trapped/injured/compressed?

Answer 1

Any point along its course

• nerve root
• plexus
• peripheral

Question 2

What are the upper limb peripheral nerves?

Answer 2

Axillary
Radial
Musculocutaneous
Ulnar
Median

Question 3

What are the lower limb peripheral nerves?

Answer 3

Sciatic
Femoral
Common peroneal
Lateral Femoral Cutaneous Nerve (LFCN)

Question 4

What are the upper limb myotome patterns?

Answer 4

C5; elbow flexors
C6; wrist extensors
C7; elbow extensors
C8; finger extensors
T1; intrinsic hand muscles

Question 5

What are the lower limb myotomes?

Answer 5

L2; hip flexors
L3; knee extensors
L4; ankle dorsiflexors
L5; long toe extenosrs
S1; ankle plantar flexors

Question 6

What are brachial plexus palsies?

Answer 6

Erb’s; upper plexus C5, 6
Klumpke’s; lower plexus C8, T1
Total brachial plexus; C5-T1

Question 7

Describe the presentation of Erb’s palsy

Answer 7

Traction of C5, 6 +/- 7

Waiter’s tip position

• shoulder adducted and IR
• elbow extended and pronated
• wrist flexed

Question 8

Describe the presentation of Klumpke’s palsy

Answer 8

Traction C8, T1

Very rare

Affects small muscles of hand; claw hand

Question 9

Describe Hilton’s law

Answer 9

A sensory nerve supplying a joint, also supplies the muscles moving the joint and the skin overlying the insertions of these muscles

Question 10

Describe the axillary nerve (origin, course etc)

Answer 10

Posterior cord of brachial plexus, C5 C6

Wraps around surgical neck fo humerus

Supplies deltoid and teres minor

Supplies skin over lateral arm; regimental badge area

*Can be damaged with shoulder dislocation and surgical neck humerus fracture

Question 11

Describe the musculocutaneous nerve (origin, course etc)

Answer 11

Lateral cord of brachial plexus, C5 C6 C7

Pierces coracobrachialis, runs inferiorly between biceps and brachialis (supplying both)

Gives supply to elbow joint

Terminates as lateral cutaneous nerve to forearm

Question 12

Describe the radial nerve (origin, course etc)

Answer 12

Posterior cord brachial plexus, C5-T1

Supplies triceps, runs in radial groove of humerus as passes from medial to lateral

Supplies BCR, ECRL, ECRB before dividing into PIN (motor) and SRN (sensory) branches

Question 13

Other terms for radial nerve palsy

Answer 13

Saturday night palsy

Crutch palsy

Question 14

Describe the symptoms of radial nerve palsy

Answer 14

Depend on site of lesion
- in axilla; loss elbow extension, wrist extension and sensory changes in forearm and hand

• in arm; loss wrist extension and sensory loss
• in forearm; loss finger extension (PIN)
• at wrist; loss sensations (SRN) i.e. handcuffs

Question 15

Describe the median nerve (origin, course etc)

Answer 15

Medial and lateral cords, C5-T1

Supplies flexors of forearm (bar FCU and medial FDP), LOAF muscles

LOAF = lateral two lumbricals, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis

Question 16

What does the pneumonic LOAF stand for?

Answer 16

4 small muscles of the hand supplied by median nerve

• Lateral two lumbricals
• Opponens pollicis
• Abductor pollicis brevis
• Flexor pollicis brevis

Question 17

What are the contents of the carpal tunnel?

Answer 17

FDS tendons x4
FDP tendons x4
FPL tendon
Median nerve

9 tendons + nerve

Question 18

What are some causes of carpal tunnel syndrome?

Answer 18

Developmental

Trauma i.e. distal radius fracture

Swellings i.e. ganglia, fibroma, lipoma

Inflammatory; rheumatoid, gout, TB, amyloid

Metabolic; preg, hypothyroidism

Question 19

Describe presentation of carpal tunnel syndrome

Answer 19

• nocturnal pain and paraesthesia in part or all of medial nerve distribution
• wasting of thenar muscles

Question 20

What to look for on examination of carpal tunnel syndrome?

Answer 20

Thenar wasting
Previous scars
Deformity (previous fracture?)

Question 21

What are tests for carpal tunnel syndrome?

Answer 21

Tinnels; tapping over nerve

Phalens; hands in inverted prayer position for 60secs

Question 22

Describe the ulnar nerve (origin, course etc)

Answer 22

Medial cord, C8 T1

No branches in arm; enters forearm between two heads of FCU

Supplies medial FDP, FCU and all intrinsic hand muscles except LOAF

Sensation to ulnar 1.5 digits

Question 23

Where is the cubital tunnel?

Answer 23

Between medial epicondyle and olecranon

Fascial bands from FCU form roof

Question 24

Describe cubital tunnel syndrome

Answer 24

Second most common nerve entrapment

Patient has numbness on ulnar side of hand and difficulty with fine tasks

Question 25

Describe ulnar nerve palsy presentation

Answer 25

Muscle wasting

• 1st webspace (often most marked)
• Guttering
• Hypothenar wasting

Ulnar claw hand; hyperextension MCPJ, flexion IPJ

Question 26

What is the ulnar paradox?

Answer 26

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

Question 27

Describe Froment’s test

Answer 27

Muscles;

• Adductor pollicis (UN)
• Flexor pollicis longus (MN)

If ulnar nerve not working patient will cheat and use FPL to maintain hold of paper instead of Adductor pollicis

Question 28

Describe the common peroneal nerve (origin, course etc)

Answer 28

Branch of sciatic nerve

Wraps around neck of fibula

Divides into deep peroneal (supply ant compartment) and superficial peroneal (supply lat compartment)

Question 29

Describe presentation of common peroneal nerve palsy

Answer 29

Foot drop

Question 30

What is and what causes meralgia parasthetica?

Answer 30

Altered sensation and pain lateral thigh

Compression of lateral femoral cutaneous nerve of thigh as it travels under lateral border of inguinal ligament