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Anatomy Upper Limbs > Brachial plexus and nerve lesions > Flashcards

Brachial plexus and nerve lesions Flashcards

1
Q

what does the posterior cord supply?

A

extensors

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2
Q

main nerves coming off the posterior cord?

A

axillary and radial nerves

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3
Q

what does the lateral cord supply?

A

flexors

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4
Q

what does the medial cord supply?

A

flexors

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5
Q

roots of the axillary nerve?

A

Roots: C5 and C6.

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6
Q

motor function of the axillary nerve?

A

Motor Functions: Innervates the teres minor and deltoid muscles.

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7
Q

sensory function of the axillary nerve?

A

Sensory Functions: Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid (“regimental badge area”).

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8
Q

roots of the musculocutaneous nerve?

A

C5, C6, C7

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9
Q

motor function of the musculocutaneous nerve?

A

Innervates the brachialis, biceps brachii and coracobrachialis muscles.

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10
Q

sensory function of the muscuocutaneous nerve?

A

Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm.

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11
Q

roots of the median nerve?

A

C6 – T1. (Also contains fibres from C5 in some individuals).

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12
Q

motor function of the median nerve?

A

Innervates most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbricals associated with the index and middle fingers.

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13
Q

sensory function of the median nerve?

A

Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand.

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14
Q

roots of the radial nerve?

A

C5 – T1

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15
Q

motor function of the radial nerve?

A

Innervates the triceps brachii, and the muscles in the posterior compartment of the forearm (which are primarily, but not exclusively, extensors of the wrist and fingers).

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16
Q

sensory function of the radial nerve?

A

Innervates the posterior aspect of the arm and forearm, and the posterolateral aspect of the hand.

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17
Q

roots of the ulnar nerve?

A

C8 and T1

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18
Q

motor function of the ulnar nerve?

A

Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus.

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19
Q

sensory function of the ulnar nerve?

A

Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area.

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20
Q

which spinal levels contribute to the brachial plexus?

A

C5-T1

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21
Q

what palsy is caused by damage to the upper brachial plexus roots?

A

C5/C6 injury leads to Erb-Duchenne Palsy

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22
Q

what are the causes of upper root injury?

A

Shoulder dystocia (during delivery of the baby, a shoulder is stuck behind the mother’s pubic bone)

Tugging of the neck during delivery

stretching of the neck relative to the shoulder

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23
Q

what nerves are affected by Erb’s palsy?

A

C5 or C6 roots: musculocutaneous
axillary
suprascapular
nerve to subclavius.

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24
Q

what muscles are affected by Erb’s palsy?

A

Supraspinatus, infraspinatus, subclavius, biceps brachii, brachialis, coracobrachialis, deltoid and teres minor.

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25
Q

what are the features of Erb’s Palsy?

A

Wasted deltoid and biceps/brachialis
Arm is pronated and medially rotated
Elbow extended
Dermatomal sensory loss

“Waiter’s tip” position: forearm is pronated due to the loss of biceps brachii. wrist is weakly flexed due to the normal increased tone of the wrist flexors relative to the wrist extensors

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26
Q

what palsy is caused by injury to the lower Brachial plexus roots?

A

Klumpke’s Palsy

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27
Q

what is the cause of Klumpke’s palsy?

A

excision abduction of the arm e.g. when breaking a fall by catching a branch, falls from ladders etc

can occur during birth when the child’s arm is pulled out (rare)

this had a lower incidence than Erb’s palsy

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28
Q

which nerves are affected in Klumpke’s Palsy?

A

Nerves derived from the T1 root – ulnar and median nerves.

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29
Q

which root is more commonly affected in Klumpke’s?

A

T1 (or can be C8 aswell)

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30
Q

which muscles are affected in Klumpke’s?

A

All the intrinsic hand muscles

31
Q

features of Klumpke’s

A

Possible Horner’s syndrome (if T1 affected)
Intrinsic hand muscles paralysed
“Claw Hand” supinated forearm with flexed wrist and fingers
Dermatomal sensory loss (medial side of arm)

32
Q

what causes the “claw hand” in Klumpke’s?

A

Unopposed action of the finger extensor muscles.
The lumbrical muscles flex the metacarpophalangeal joints and extend the interphalangeal joints, so their paralysis will cause the opposite: extension of the MCP and flexion of the IP joints.

33
Q

how can the musculocutaneous nerve be damaged?

A

in surgery for breast cancer due to the location of lymph nodes

shoulder dislocation

weight lifters are prone to this

34
Q

what is the effect of a damage musculocutaneous nerve?

A
  • Weak elbow flexion and supination
  • Absent biceps reflex
  • Lateral forearm sensory loss (lateral cutaneous nerve)
35
Q

how can the axillary nerve be damaged?

A

shoulder dislocations

humeral head and neck fractures

36
Q

what is the effect of axillary nerve damage?

A
  • deltoid wastage (flat shoulder deformity alongside teres minor wastage)
  • Loss of abduction (from >15°)
  • Sensory loss on lateral upper arm in the
    Regimental badge patch
37
Q

what can cause a radial nerve injury?

A

injury to the axilla
humeral shaft fracture
fracture of the radial neck below the elbow

38
Q

what are the effects of a radial nerve injury?

A
  • Wrist drop: cannot extend the wrist, elbow or fingers
  • muscle wastage (when the lesion is higher up)
  • Sensory loss to posterior forearm and dorsum of hand (anaesthesia)
  • loss of the power grip due to loss of wrist extension
39
Q

what are the causes of median nerve injury?

A
  • supracondylar humeral fracture
  • wrist lacerations
  • carpal tunnel syndrome (compression)
40
Q

what are the effects of median nerve damage?

A
  • Loss of sensation in lateral three and a half fingers
  • Loss of wrist flexion, elbow pronation, flexion of radial ½ of digits
  • Presence of “benediction sign”
  • Presence of ape hand deformity
  • loss of thenar eminence due to wasting
41
Q

what are the 4 pillars of the carpal tunnel?

A

hook of hamate
pisiform
crest of trapezium
tubercle of scaphoid

42
Q

what are the causes of ulnar nerve injury?

A
  • elbow fractures
  • wrist trauma (e.g. self harm)
  • funny bone trauma
43
Q

what are the effects of ulnar nerve damage?

A
  • Sensory loss in medial 1½ fingers (palmar and dorsal)

- Ulnar claw

44
Q

ulnar claw

A

Hyper-extended 4th and 5th digits at MCP
Hyper-flexed 4th and 5th digits at IPJs
Weak thumb adduction “Froment’s sign”
Claw worse on extension (unlike median nerve)

the lumbricals contraction loss leads to no flexion at knuckles
PAD and DAB affected

45
Q

what is the ulnar paradox?

A

claw deformity is more severe with wrist damage than with elbow damage

“the closer to the paw, the worse the claw”

46
Q

what is the effect of damage to the long thoracic nerve?

A

winging of the scapula (unopposed action of the rhomboids pushes scapula back)

paralysis of serratus anterior

47
Q

what is the function of the serratus anterior?

A

protect and stabilise the scapula

48
Q

proximal and distal attachment of the serratus anterior muscle?

A

upper 8/9 ribs

medial margin of scapula

49
Q

what can cause long thoracic nerve damage?

A

surgery for breast cancer

50
Q

what are the muscles of the rotator cuff?

what is each muscle innervated by?

A
  • Supraspinatus (suprascapular n)
  • Infraspinatus (suprascapular n)
  • Teres minor (axillary n)
  • Subscapularis (lower subscapular n)
51
Q

what is the function of the rotator cuff muscles as a whole?

A

keep the humeral head inside the glenoid fossa

52
Q

myotomes

A

the more distal the movement occurs at, the lower down the spinal root

opposing movements tend to be innervated from adjacent spinal segments

53
Q

Shoulder Abduction

A

C5 (axillary)

54
Q

Shoulder Adduction

A

C6/7/8

55
Q

Elbow Flexion

A

C5 (musculocutaneous)

56
Q

Elbow extension

A

C7 (radial)

57
Q

Wrist Flexion & Extension

A

C6/7 (radial)

58
Q

Finger Flexion

A

C8 (median)

59
Q

Finger Extension

A

C7 (radial)

60
Q

Finger Abduction –

A

T1 (ulnar)

61
Q

Abductor pollicis brevis

A

T1 (median)

62
Q

which nerves are tested by the biceps jerk?

A

C5/C6

63
Q

what nerves are tested by the triceps jerk?

A

C6/C7

64
Q

what nerves are tested by the brachioradialis reflex?

A

C6/C7

65
Q

signs of tendon sheath infection

A

Finger held in flexion
Swelling
Tenderness along the flexor tendon sheath
Pain with passive extension of the digit

66
Q

how can bacterial infection spread to the hand and wrist

A

FDM tendon sheath to ulnar bursa

FP tendon sheath to radial bursa

67
Q

why are flexor tendons enclosed in a sheath?

A

for lubrication and as a pulley

68
Q

frozen shoulder (Adhesive capsulitis”)

A 
Seen in trauma
Chronic pain and cramps, worse on moving
NSAIDs and steroids can help
Physiotherapy or manipulation under anaesthetic can help break up the adhesions
Surgery only if very severe
69
Q

shoulder impingement

A

Tendons of rotator cuff become inflamed as they pass under the acromion
Can be due to trauma or age-related degeneration
Weakness, pain and reduced movement

70
Q

diagnosing and testing shoulder impingement

A

Hawkins-Kennedy test

Treatment:

  • Conservative (PT and pain relief)
  • Steroid or local anaesthetic injection
  • Surgery if severe
71
Q

What is a colles fracture?

A

Fall onto outstretched arm with wrist extended

Distal radial fracture with dorsal displacement of the distal radial fragment (Dinner form deformity)

72
Q

why is a scaphoid bone fracture clinically significant?

A

Scaphoid bone supplied by radial artery branches
Fracture in proximal 1/3 leads to avascular necrosis of proximal fragment (blood supply runs from distal to proximal)

therefore snuff box injuries need to be taken seriously and an MRI may need to be done (x-ray can be non disclosing)

73
Q

acromioclavicular joint damage

A

Usually sports injuries where fall onto point of shoulder

Scapula forced downward and clavicle looks very prominent

Anatomy Upper Limbs (3 decks)

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