Peripheral Nerve

Question 1

Anterior interosseous nerve muscles

Answer 1

Prone on all Fours (Pronator Quadratus) F PLease DP. Anterior interosseous. (Palmaris longus is superficial, therefore not supplied by AIN)

3 muscles.
PQ
FPL
FDP

Pain in forearm, unable to make pincer

Question 2

Sign of Benediction

Answer 2

Proximal median nerve injury.
Active.
Loss of the radial flexor muscles, therefore during active finger flexion, there is the hand of benediction. Only ulnar two digits can flex (supplied by ulnar nerve)

Question 3

Ape Hand

Answer 3

Median nerve injury.
Loss of thenar muscles (Abd Pollicis, flexor pollicis)
Unopposed Adductor pollicis, and **extensor pollicis, **that pulls thumb into same plane as other fingers.

Question 4

Ulnar paradox

Answer 4

Proximal ulnar nerve injury leads to straight hand, whereas distal ulnar nerve injury leads to claw hand.
Due to whether FDP is affected.
Unaffected in distal injury, therefore there is unopposed action (lose the finger extension contribution by lumbricals and interossei)
Affected in proximal lesion, therefore there is no opposed finger flexion.
Seen at rest, unlike hand of benediction.

Question 5

Wartenberg sign:

Answer 5

Abducted little finger, due to loss of the third (3 = W) interossei muscle in ulnar nerve compression.

Catch little finger when putting into pocket.

Question 6

Martin Gruber anastomosis NCS findings

Answer 6

Poor amplitude of ulnar nerve throughout, (at wrist, above elbow, below elbow, axilla etc.)

Good amplitude at wrist, due to anastomosis from median nerve.

FDI (first dorsal interossei) and ADM (abductor digiti minimi) signal from median nerve stimulation, both are normally supplied by ulnar nerve

Question 7

Erb palsy

Answer 7

C5/6 injury, at birth.

Erb = Extended waiter tip.

Unopposed extension of arm due to loss of arm flexors.
Pronator and hand muscles intact, due to lower root supply.

Question 8

Klumpke Palsy

Answer 8

Klumpke Claw

C8/T1 root injuries

Loss of intrinsic hand muscles.

Forearm supinated, loss of pronator tone.

Question 9

Nerve supply to lat Dorsi

Answer 9

ThoracoDorsal

(Tom Doke likes boobs, lat dorsi flap)

Question 10

Common sites of radial nerve compression

Answer 10

Proximal humerus: Saturday night palsy

Humerus fracture through spinal groove

Arcade of Frohse (at supinator). PIN wrist and finger drop.

Cheralgia paraesthetica
WArtenburg Syndrome

Question 11

Common sites of ulnar nerve compression

Answer 11

Arcade of Struthers
Osborne membrane
FCU muscle
Guyon canal

Question 12

Pronator syndrome

Answer 12

median nerve entrapment in the proximal forearm. Get proximal arm pain and tenderness. See it in patients with well developed pronators and forearm muscles, eg muscle builders.

Question 14

Struther ligament vs.
Arcade of Struthers

Answer 14

Ligament: tip of supracondylar process to the medial epicondyle.

Arcade: 6cm proximal to the medial epicondyle, and is formed from medial head of triceps muscle with intermuscular septum.

Question 15

Principles of Peripheral nerve sheath tumour surgery:

Answer 15

• Find the fascicles
• Find epineurium of the tumour, and incise this
• Widen exposure, ensure entire tumour is visualised.
• Find fascicle where the tuour is arising from. Usually this is sensory, and can be sacrificed. Dissect out and push the rest of the fascicles down and out of the way.

Question 17

C5 vs Axillary nerve palsy

Answer 17

Ask to externally rotate and feel for Teres minor muscle, if absent, Axillary. Also feel deltoid.

C5 includes rhomboids and Supraspinatus, and also help to elevate deltoid. Feel for Supraspinatus during shoulder abduction