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Y1 - MSK > Upper Limb Nerve Injuries > Flashcards

Upper Limb Nerve Injuries Flashcards

1
Q

What is a myelopathy?

A

Spinal cord injury

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2
Q

What is affected in a Myelopathy (spinal cord injury)?

A

Anything below the injury

So you get a neural level

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3
Q

What is a clinical neural level?

A

The lowest functional level of sensation and motor function

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4
Q

What is a radiculopathy?

A

Spinal nerve injury

Only the 1 spinal nerve is damaged

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5
Q

What is affected as a result of a radiculopathy (spinal nerve injury?

A

Only the affected spinal nerves Dermatome and Myotome

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6
Q

What is peripheral neuropathy?

A

A peripheral nerve injury (made up from multiple spinal nerves)

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7
Q

What is affected as a result of a peripheral nerve injury?

A

Loss of that specific nerves function

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8
Q

What is the most common direction of intervertebral disc herniation?

A

Posterolateral/paracentral

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9
Q

In the lumbar spine where does the nerve root emerge with respect to its corresponding spinal vertebra?

A

Below its vertebra

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10
Q

In the cervical spine where does the spinal nerve root emerge with respect to its corresponding vertebra?

A

Above its corresponding vertebra

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11
Q

What spinal nerve root is compressed in a paracentral disc herniation of the lumbar spine?

A

Traversing root

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12
Q

What spinal nerve root is compressed in a paracentral disc herniation of the cervical spine?

A

The emerging root

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13
Q

What are the 4 types of nerve injury?

A

4 S’s
Stretched (traction)
Squashed (compressed)
Severed (laceration)
Stressed (underlying conditions)

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14
Q

What are the 3 types of nerve damage in the Sedonn classification?

A

I Neuropraxia
II Axonotmesis
III Neurotmesis

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15
Q

What is neuropraxia?

Is the axon in tact?

Is the connective tissue in tact (endo, peri and Epineurium)?

Does wallerian degeneration happen?

A

When the myelin sheath is damaged affecting conduction

Yes

Yes

No Wallerian degeneration

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16
Q

What is Axonotmesis?

Is the axon in tact?

Is the connective tissue in tact (endo, peri and Epineurium)?

Does wallerian degeneration happen?

A

Disruption of the axon

Axon not in tact

Connective tissue in tact

Yes Wallerian degeneration distal from damage

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17
Q

What is Neurotmesis?

Is the axon in tact?

Is the connective tissue in tact (endo, peri and Epineurium)?

Does wallerian degeneration happen?

A

When the axon and the connective tissue is cut

Axon not in tact

CT not in tact

Yes Wallerian degeneration

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18
Q

What are the nerve roots of the Musculocutaneous nerve?

A

C5, C6 and C7

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19
Q

What is the mechanism of damage to the Musculocutaneous nerve?

A

Trauma to the armpit (axilla)/Iatrogenic

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20
Q

What is the motor innervation of the musculocutaneous nerve?

A

Biceps brachii
Brachialis
Coracobrachialis

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21
Q

Why when the musculocutaneous nerve is damaged is Flexion at the elbow only weakened not lost?

A

Brachioradialis is a flexor of the elbow but is supplied by the radial nerve

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22
Q

What sensory supply is lost as a result of musculocutaneous nerve damage?

A

Lateral cutaneous nerve of the forearm

(The lateral aspect of the forearm)

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23
Q

What are the nerve roots of the Axillary nerve?

A

C5 and C6

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24
Q

What can lead to Axillary nerve damage?

A

Anterior shoulder dislocation
Surgical neck of humerus fracture
Compression in axilla

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25
Q

What 2 muscles are supplied by the Axillary nerve?

A

Deltoid
Teres Minor

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26
Q

What is the function of deltoid?

A

Abduction 15-90º

Flexion, internal rotation, extension and external rotation

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27
Q

What is the function of teres minor?

A

External rotation

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28
Q

What motor function is affected as a result of Axillary nerve damage?

A

Abduction 15-90º lost due to deltoid affected

External rotation weakness due to deltoid and teres minor affected

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29
Q

What sensory region is lost as a result of Axillary nerve damage?

A

Regimental badge region

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30
Q

What nerve roots form the long thoracic nerve?

A

C5, C6 and C7

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31
Q

What is the mechanism of damage to the long thoracic nerve?

A

Blunt trauma
Iatrogenic (mastectomy, when the lymph nodes in the axilla are removed

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32
Q

What muscle loses its innervation when the long thoracic nerve is damaged?

A

Serratus anterior

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33
Q

What is seen with long thoracic nerve damage?

Why is this seen?

A

Winging of the scapula

Serratus anterior does protraction of the scapula and holds the scapula against the rib cage

34
Q

What are the nerve roots of the radial nerve?

A

C5, C6, C7, C8 and T1

35
Q

What are the cords in the brachial plexus?

A

Lateral cord
Posterior cord
Medial cord

36
Q

What cord does the radial nerve come from?

A

Posterior cord

37
Q

What is the course of the radial nerve?

A

Starts posterior to the Axillary artery, goes laterally and runs in spiral groove of humerus. Passes between the Brachialis and brachioradialis and is lateral in the cubital fossa passing anteriorly to the lateral epicondyle
Splits into superficial and deep branch and passes between 2 heads of supinator

38
Q

What muscles does the Radial nerve pass between?

A

Brachioradialis and Brachialis

2 heads of supinator

39
Q

What motor functions does the radial nerve have?

A

Extension of elbow, wrist, MCPJ and IPJ

40
Q

What is the sensory region of the radial nerve?

A

Radial portion of dorsum of the hand and 3.5 digits but not their finger tips (superficial branch)

41
Q

What nerve can be damaged as a result of a Mid-shaft humeral fracture?

What type of damage is it normally?

A

Radial nerve
(Radial nerve palsy)

Neuropraxia

42
Q

What usually causes a mid-shaft humeral fracture?

A

Direct blow to arm
FOOSH

43
Q

Can a patient with damage to their radial nerve in the radial groove following a mid-shaft humeral fracture extend at the elbow and feel their arm and forearm?

44
Q

Why is a patient with a mid-shaft fracture of the humerus with radial nerve palsy still able to extend at the able no still feel their arm and forearm?

A

The nerves to the triceps (long and lateral head) give off before entering the spiral groove
Same it’s the sensory supply to the arm and forearm

45
Q

What is the characteristic presentation of a radial nerve palsy (damage, can happen in mid-shaft humeral fracture)?

A

Wrist drop

46
Q

Why does wrist drop occur in Radial nerve palsy when the wrist is pronated?

A

Extensor compartment of the posterior forearm supplying/causing extension at the wrist and extension at the fingers lose innervation

So unopposed Flexion at the wrist and fingers and gravity when pronated causes wrist drop

47
Q

Where is the sensory impairment as a result of radial nerve palsy?

Which branches are unaffected?

Which branch is affected?

A

Paraesthesia in dorsum of hand and dorsum of radial 3.5 digits

Posterior cutaneous nerve of arm, lower lateral cutaneous nerve of arm and posterior cutaneous nerve of forearm are usually unaffected

Superficial branch of radial nerve affected

48
Q

How can you test for the sensation of the radial nerve supplied areas?

A

Touch the first webbed space of the dorsum of the hand

49
Q

What are the nerve roots of the median nerve?

A

C5, C6, C7, C8 and T1

50
Q

What cord does the median nerve come from?

A

Medial and Lateral Cord

51
Q

What is the course of the median nerve

A

From medial aspect of arm, passing anterior to medial epicondyle, passes though 2 heads of Pronator teres to anterior forearm, pass between FDS and FDP in forearm.
Enters hand via carpal tunnel

52
Q

What muscles does the Median nerve run through and/or between?

A

Runs through 2 heads of Pronator teres to anterior forearm

Passes between FDS (Flexor Digitorum Superficialis) and FDP (Flexor Digitorum Profundus)

53
Q

What is the motor innervation of the Median nerve?

A

All anterior forearm except Flexor Carpi Ulnaris and Ulnar half of FDP

LOAF muscles

54
Q

What are the LOAF muscles?

A

Muscles innervated by the median nerve in the hand

Lumbricals (lateral/radial 2)
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis

55
Q

What is the sensory area supplied by the median nerve?

A

The palmar aspect of the radial 3.5 digits and the dorsal fingertips of these digits

56
Q

What type of injury can cause a high median nerve injury?

A

Supracondylar fracture at elbow (humerus)

57
Q

What is the sign that a patient gives when asked to make a fist when they have a HIGH median nerve injury?

A

Hand of Benediction

58
Q

What is the hand of benediction?

A

When the patient try’s to make a fist, they cant flex 2nd and 3rd finger and their thumb is Adducted and interphalangeal joint is extended

59
Q

In a high median nerve injury why are the 2nd and 3rd fingers unable to be flexed?

A

FDS and radial half of FDP lost nervous supply
They remain flexed due to the tone of the extensors

60
Q

In a high median nerve injury why is the thumb Adducted and Extended at the IPJ?

A

Adducted: Abductor pollicis brevis lost innervation (ADductor pollicis goes unopposed)

Extended IPJ: Flexor Pollicis Longus and Flexor Pollicis Brevis lost innervation (Extensor pollicis longus goes unopposed)

61
Q

What is the supply to adductor pollicis?

A

Ulnar nerve

62
Q

What supplies Extensor Pollicis longus?

A

Radial nerve

63
Q

What is ape hand deformity?

A

Long standing high median nerve injury producing a deformity at rest

Thumb can still be flexed by FPB deep head at the MCPJ but not at the Interphalangeal joint so remains extended here

64
Q

What can cause a low median nerve injury? (At the wrist)

A

Carpal tunnel syndrome compresses it

Laceration

65
Q

What is different to a median nerve injury at the wrist compared to a high median nerve injury?

A

The forearm muscles are still intact (So not constantly supinated like in a high median nerve injury)

But like high median nerve injury LOAF muscles compromised

Only sensory loss to the radial 3.5 digits

66
Q

Why in a median nerve injury at the wrist (carpal tunnel syndrome) is sensory loss only at the radial 3.5 digits and not the radial palm too?

A

Palmar cutaneous branch of median given off to supply palmar surface of hand before the carpal tunnel

67
Q

What are the spinal nerve roots of the ulnar nerve?

68
Q

What cord does the ulnar nerve come from?

A

Medial cord

69
Q

What is the course of the ulnar nerve?

A

Medial aspect of arm passes posteriorly to medial epicondyle in cubital tunnel. Passes through 2 heads of flexor carpi ulnaris to enter anterior forearm and branches deep to this muscle in forearm.
Enters hand via Guyons canal

70
Q

What is the motor function of the ulnar nerve?

A

Flexor carpi ulnaris
Ulnar 1/2 of FDP
Ulnar 2 lumbricals
All interossei (PADs + DABs)
Hypothenar eminence
Adductor pollicis

71
Q

What is the sensory innervation of the ulnar nerve?

A

Ulnar 1.5 digits of hand
Ulnar part of palm

72
Q

What can cause a distal/low ulnar nerve injury?

A

Laceration
Compression in Guyons canal

73
Q

What muscles would be affected by a distal/low ulnar nerve injury?

A

Intrinsic hand muscles except the LOAF muscles

Ulnar 2 lumbricals, interossei lost

74
Q

Describe the ulnar claw seen in a distal/low ulnar nerve injury:

A

Happens at rest

Affects digits 4 and 5
Hyperextension at MCPJs
Flexion at PIPJs
Flexion at DIPJs

75
Q

Why is Hyperextension at MCPJs and Flexion at PIPJs and DIPJs seen at digits 4 and 5 in a distal/low ulnar nerve injury?

A

Ulnar 2 lumbricals lost innervation

Lumbricals flex at the MCPJ and extend at the PIPJ and DIPJ

So the forearm extensors at the MCPJ go unopposed causing hyperextension
The forearm flexors at the DIPJ and PIPJs go unopposed (FDP + FDS)

76
Q

What can cause a proximal/high ulnar nerve injury?

A

Medial epicondyle fracture (humerus)
Cubital tunnel syndrome

77
Q

What muscles lose innervation as a result of a high/proximal ulnar nerve injury?

A

Intrinsic hand muscles except LOAF
Flexor Carpi Ulnaris
Ulnar half of Flexor Digitorum Profundus (so the ulnar supplied forearm muscles also affected)

78
Q

What sensory loss takes place as a resul of a high/proximal ulnar nerve injury?

A

All branches lost

79
Q

Describe the ulnar claw seen in a high/proximal ulnar nerve injury:

A

Seen at rest at 4th and 5th digits

Hyperextension at MCPJs
Flexion at PIPJs
Normal/extended DIPS

80
Q

Why is Hyperextension at MCPJs and Flexion at PIPJs and Extension at DIPJs seen at digits 4 and 5 in a high/proximal ulnar nerve injury?

A

Hyperextension at MCPJs due to loss of ulnar 2 lumbricals ability to flex

Flexion at PIPJs due to FDS having reduced extension to oppose

Extension at DIPJs due to loss of Ulnar Half of FDP
FDP flexes at the DIPJs. So despite lumbricals lost the main flexor for this is lost so it stays extended

81
Q

What is the Ulnar paradox?

A

A high/proximal ulnar nerve injury creates a ulnar claw deformity that doesn’t appear as deformed as a low/distal ulnar nerve injury

Despite the high/proximal ulnar nerve injury leading to more muscles losing innervation

Y1 - MSK (36 decks)

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