Upper Limb

Question 1

Identify the brachial plexus lesions

Answer 1

1. upper/superior trunk lesion: Walter’s tip (Erb’s palsy)
2. lower/inferior trunk lesion –> Claw hand (Klumpke’s palsy)
3. posterior cord lesion –> Wrist drop and some difficulty with shoulder abduction (b/c posterior cord –> axillary nerve and radial nerve)
4. long thoracic lesion –> winged scapula
5. axiliary nerve lesion –> deltoid paralysis
6. radial nerve lesion –> “Saturday night palsy” (wrist drop)
7. musculocutaneous nerve lesion –> difficulty flexing elbow, variable sensory loss
8. median nerve –> decreased thumb function –> Pope’s blessing
9. ulnar nerve –> intrinsic muscles of hand, claw hand

Question 2

Axillary (C5, C6)

typical injury:
motor deficit:
sensory deficit:
sign:

Answer 2

• typical injury: fractured surgical neck of humerus; dislocation of humeral head
• motor deficit: deltoid - arm abduction at shoulder
• sensory deficit: over deltoid muscle
• sign: atrophied deltoid

Question 3

Radial (C5-T1)

typical injury:
motor deficit:
sensory deficit:
sign:

Answer 3

• typical injury:
  
  • fracture at midshaft of humerus
  • Saturday night palsy - extended compression of axilla by back of chair or crutches
• motor deficit: BEST extensors
  
  • brachioradialis
  • extensors of wrist and fingers
  • supinator
  • triceps
• sensory deficit: posterior arm and dorsal hand and thumb
• sign: wrist drop

Question 4

median nerve (C5-8, T1)

typical injury:
motor deficit:
sensory deficit:
sign:

Answer 4

• typical injury: fracture of supracondylar humerus (proximal lesion)
• motor deficit:
  
  • opposition of thumb
  • lateral finger flexion
  • wrist flexion
• sensory deficit:
  
  • dorsal and palmar aspects of lateral 3.5 fingers
  • thenar eminence
• sign:
  
  • ape’s hand
  • Pope’s blessing

Question 5

ulnar nerve (C8, T1)

typical injury:
motor deficit:
sensory deficit:
sign:

Answer 5

• typical injury: fracture of medial epicondyle of humerus, “funny bone” (proximal lesion)
• motor deficit:
  
  • medial finger flexion
  • wrist flexion
• sensory deficit:
  
  • medial 1/2 fingers
  • hypothenar eminence
• sign:
  
  • radial deviation of wrist upon wrist flexion

Question 6

musculocutaneous (C5-7)

typical injury:
motor deficit:
sensory deficit:
sign:

Answer 6

• typical injury: upper trunk compression
• motor deficit:
  
  • biceps
  • brachialis
  • coracobrachialis
  • flexion of arm at elbow
• sensory deficit:
  
  • lateral forearm
• sign: —

Question 7

Caveat . . . always consider the lesion location

Answer 7

Generally, muscles innervated by nerve branches distal to the lesion will be affect. The preceding flashcards are highly simplified.

Question 8

What is the most commonly fractured carpal bone?

Answer 8

the scaphoid

• presentation usu includes pain on lateral side of wrist in anatomic snuffbox esp with dorsiflexon and abduction of hand

Question 9

Describe scaphoid fracture on x-ray.

Answer 9

• fracture hard to detect immediately post-injury
• but within few weeks proximal fragment under goes avascular necrosis –> bone reabsorbed –> noticeable hypodensity on x-ray

Question 10

Explain carpal tunnel syndrome.

Answer 10

• The median nerve is compressed in the carpal tunnel btw the flexor tendons and the flexor retinaculum
• Result:
  
  • decreased sensation on 1st 3.5 digits
  • loss of strength of thumb due to weakness of abductor pollicis brevis & opponens pollicis muscle

Question 11

Thenar Eminence includes which muscles?

Answer 11

OAF

• Opponens pollicis
• ABductor pollicis brevis
• Flexor pollicis brevis

this is all median nerve

Question 12

Hypothenar eminence includes which muscles?

Answer 12

OAF

• Opponens digiti minimi
• ABductor digiti minimi
• Flexor digiti minimi

Question 13

What do the dorsal interosseous muscles do?

Answer 13

ABduct the finger

DAB = Dorsal interosseous ABduct the fingers

Question 14

What do palmar interosseous muscles do?

Answer 14

ADDuct the fingers

PAD = Palmar interosseous muscles ADduct the fingers

Question 15

What do lumbrical muscles do?

Answer 15

flex at the MCP joint, extend PIP and DIP joints

Question 16

“clawing” of hand

Answer 16

loss of lumbricals, which flex the MCP and extend the PIP and PIP joints

Question 17

ulnar claw

Answer 17

• can be caused by longstanding injury to ulnar nerve at hook of hamate (by falling onto outstretched hand)
• distal ulnar nerve lesion –> loss of medial lumbrical fxn –> inability to extend 4th and 5th digits (“clawing”) when trying to open the hand

Question 18

median claw

Answer 18

• some causes:
  
  • carpal tunnel syndrome
  • dislocated lunate
• distal ulnar nerve lesion (after branch containing C5-7 branches off to feed forearm flexors) –> loss of lateral lumbrical fxn
• 2nd and 3rd digits clawed upon attempted finger extension

Question 19

“Pope’s blessing”

Answer 19

• proximal median nerve lesion causes loss of lateral finger flexion and thumb opposition
• when asked to make a fist, 2nd and 3rd digits remain extended and thumb remains unopposed, which looks like the hand of benediction or “Pope’s blessing”

Question 20

Ape hand

Answer 20

Proximal median nerve lesion –> loss of opponens pollicis muscle fxn –> unopposable thumb (inability to abduct thumb), hence “ape hand”

Question 21

Klumpke’s total claw

Answer 21

• lesion of lower trunk (C8, T1) of brachial plexus –> loss of function of all lumbricals
• forearm finger flexors (fed by part of median nerve with C5-7) and finger extensors (fed by radial nerve) are unopposed –> clawing of all digits