Nerve Pathologies

Question 1

CN XI

Answer 1

Posterior cervical triangle and can be injured with cervical lymph node biopsy
-leads to shoulder drooping/weakness

Question 2

Brachial Plexus: upper trunk pathology

Answer 2

• Nerves involved: suprascapular, musculocutaneous, axillary, partis of medial and radial
• Weakness: SHOULDER flex, abd, ext; ELBOW flex, supination, pronation WRIST flexion
• Paresthesias in lateral hand and forearm and thumb = index finger

Question 3

Brachial plexus: middle trunk pathology

Answer 3

• Rarely injured in isolation

- presents as radial nerve palsy but affects triceps and spares BR

Question 4

Brachial plexus: lower trunk lesion

Answer 4

• Motor weakness in muscles innervated by ulnar nerve, C8 components of radial, distal median nerve (thenar and lumbricals)
• Paresthesias at medial forearm, hand and 4th and 5th digits

Question 5

Brachial plexus: lateral cord lesion

Answer 5

similar to upper trunk lesion but SPARES suprascapular and partially affects axillary and radial
-Look for normal shoulder function with musculocutaneous nerve palsy signs/Sx

Question 6

Brachial plexus: medial cord lesion

Answer 6

Similar to lower trunk lesions but normal finger extension strength

Question 7

Brachial plexus: posterior cord lesion:

Answer 7

rare in isolation

Question 8

Suprascapular Nerve:

Answer 8

C5-6 from upper trunk

• travels through suprascapular notch under transverse scapular ligament and then through spinoglenoid notch
• *if compressed at scapular spine or spinoglenoid ligament may cause infraspinatus wasting w/ supraspinatus sparring

Question 9

Axillary Nerve

Answer 9

C5-6 from posterior cord

• @ greatest risk with dislocation. proximal humeral Fx, shoulder surgery
• supplies delt and teres minor

Question 10

Long Thoracic nerve:

Answer 10

C5-7 direct from roots

• supplies SA
• Ruckshack palsy: upper trunk and/or long thoracic nerve palsy (named for Vietnam soldiers who carried heavy ammunition in packs)

Question 11

Musculocutaneous nerve

Answer 11

C5-7 from lateral cord

• Supplies b/brachii and brachialis
• also branches to supply lateral forearm (lateral antebrachial cutaneous)
• MOI: distal humeral Fx, clavicular Fx, entrapment of brachioradialis, shoulder harness after MVA

Question 12

Radial Nerve: pathway

Answer 12

C5-C8 (sometimes T1); posterior cord

• Exits axilla distal to t.major
• Travels along humerus in radial groove
• posterior brachial cutaneous and posterior antebrachial cutaneous branch provide sensory innervation from axilla distally to wrist
• Divides into superficial and deep branches in antecubital space
• Superficial branch: sensory to distal PL wrist–> terminates as digital nerves (sensory to back of hand)
• Deep branch passes beneath supinator, innervates it, and becomes PIN (**common entrapment site)

Question 13

Ulnar nerve: pathway

Answer 13

C8-T1; medial cord

• NO major branches in arm/brachium
• passes through medial intermuscular septum
• 1st branch @ elbow level to innervate JC-passes posterior to medial epicondyle emerging through cubital tunnel
• cutaneous branches innervate medial side of wrist and hand

Question 14

Median nerve: pathyway

Answer 14

• medial side of antecubital fossa beneath brachial aponeurosis
• passes through P.teres and arises as AIN
• Median N innervates FCR, P.longus, and FDS
• AIN innervates FPL, lateral 1/2 of FDP, thumb intrinsics and radial lumbricals
• cutaneous innervation at posterior side digits 1-3 and 1/2 digit 4

Question 15

Median nerve: motor loss, Sensory loss and Functional loss

Answer 15

M: P.teres, P.quadratus, FCR, P.longus, FDS, lateral 1/2 FDP, thenar eminence, lateral 2 lumbricals

S: Palmar aspect of hand with thumb, index, middle, and lateral 1/2 ring

F: pronation weakness, wrist flex/abd weak, loss RD at wrist, can’t oppose/flex thumb, thumb abduction weakness, weak grip, weak/no pinch (APE hand)

Question 16

AIN: motor loss, sensory loss, functional loss

Answer 16

M: FPL, lateral 1/2 FDP, P.quadratus, thenar eminence mms, lateral 2 lumbricals

S: NONE

F: pronation weakness, esp in 90 deg elbow flexion, weak thumb opposition/flexion, weak finger flexion, weak pinch (no tip to tip)

Question 17

Ulnar nerve: motor loss, sensory loss, functional loss

Answer 17

M: FCU, medial 1/2 FDP, P. brevis, hypothenar eminence, Add policis, medial 2 lumbricals, ALL interossei

S: posterior and palmar aspect of little and medial 1/2 ring finger

F: weak wrist flex, no UD, loss distal finger flex at 5th digit, loss ABD/ADD fungers, can’t extend 4th and 5th distal and middle PH, loss thumb adduction

Question 18

Radial nerve loss motor, sensory, function

Answer 18

M: Anconeus, BR, ECRL, ECRB, ED, ECU, EPL, EPB, APL, IE, EDM

S: posterior aspect of hand (lateral 2/3), poserior and lateral aspects of thumb, prox 2/3 posterior aspect of index and 1/2 ring finger

F: loss supination, loss wrist ext, can’t grip/stabilize wrist, loss finger ext, cant abduct thumbs

Question 19

PIN: motor loss, sensory loss, functional loss

Answer 19

M: ECRB, EPL, ED, EPB, ABD PL, ECU, EI, EDM

S: NONE

F: weak wrist/finger ext, can’t stabilize wrist, can’t grasp, can’t abduct thumb

Question 20

Saphenous Nerve

Answer 20

largest cutaneous branch of femoral nerve; sensory to medial foot/arch

Question 21

Common fibular (peroneal) Nerve: Branches and innervation

Answer 21

Splits into superficial and deep peroneal nerves

SUP: sensory to dorsum of foot (NOT 1st web space); motor to peroneals

DEEP: Sensory to 1st web space; motor to ankle/toe DF

Question 22

Sural Nerve

Answer 22

Sensory to posterolateral foot

Question 23

Tibial nerve divisions and innervation

Answer 23

sural, medial calcaneal, medial plantar and lateral plantar nerves

tibial nerve motor to PFs and intrinsics