Nerve Injuries In The Lower Limb Flashcards

1
Q

What is the term for a spinal cord injury?

A

Myelopathy

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2
Q

What is the term for a spinal nerve root injury?

A

Radiculopathy

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3
Q

What is the term for a Peripheral nerve injury?

A

Peripheral Neuropathy

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4
Q

What affect does Myelopathy have on the body?

A

No communication (paralysis) below point of damage

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5
Q

What affect does Radiculopathy have on the body?

A

Only affects specific Dermatome and myotome supplied by the spinal nerve root

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6
Q

What affect does Peripheral Neuropathy have on the body?

A

Loss of that specific nerves function

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7
Q

What are the 4 S’s for describing the ways nerves can become damaged?

A

Stretched (“Traction”)
Squashed (“Compressed”)
Severed (“Laceration”)
Stressed (By medical conditions)

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8
Q

Briefly, what is the structure of a nerve?

A

Axon
Surrounded by Endoneurium
Many parallel axons surrounded by perineurium to form a fascicle
Many fascicles surrounded by Epineurium forms the nerve

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9
Q

What are the 3 classifications of nerve injury in Seddon Classification?

A

Class I = Neuropraxia
Class II = Axonotmesis
Class III = Neurotmesis

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10
Q

What is Wallerian degeneration?

A

The degeneration of axons distal to an injury

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11
Q

What is Class I Neuropraxia nerve injury?

A

Temporary physiological block of conduction along axon

No disruption to nerve structure (NO Wallerain degeneration)
ENDO/PERI/EPIneurium intact

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12
Q

What is the recovery like for Neuropraxia?

A

FULL recovery in days-weeks

Mildest form of nerve damage

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13
Q

What is Class II Axonotmesis?

A

Axons divided
Axon and myelin sheath disrupted (Wallerian degeneration)
EPI/PERI/ENDOneurium still intact

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14
Q

What is recovery like from an Axonotmesis injury?

A

Axon regeneration can occur
Don’t normally need surgery
Recovery time depends on the cut axons distance from target site

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15
Q

What is Class III Neurotmesis?

A

Partial or full disruption to the nerve structure (ENDO/PERI/EPI and axons)

Wallerian degeneration

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16
Q

What is recovery like for a Neurotmesis injury?

A

Needs surgery since scar tissue between the divided fascicles prevents regeneration

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17
Q

What cells guide the direction an axon regenerates in?

A

Schwann cells

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18
Q

In an intervertebral disc prolapse/herniation, which direction does this normally happen?

A

Paracentrally

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19
Q

Which nerve is typically affected with a paracentral disc herniation?

A

Traversing root

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20
Q

What is the traversing root?

A

So at the L4-L5 level L4 is the exiting root
L5 is the traversing root

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21
Q

What does Iatrogenic injury mean?

A

Injury caused by doctor intervention (surgery may damage a nerve)

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22
Q

What are the ways that the Femoral nerve can be damaged?

A

Direct trauma
Iatrogenic
Nerve blocks

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23
Q

What are the 2 branches of the femoral nerve

A

Anterior femoral cutaneous nerve

Saphenous nerve

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24
Q

Where does the femoral cutaneous nerve inveterate?

A

Anteromedial thigh

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25
Q

Where does the saphenous nerve supply?

A

Medial leg

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26
Q

Where does the femoral nerve branch into the saphenous nerve?

A

Quite high up in the femoral triangle

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27
Q

What is the motor function of the femoral nerve?

A

Hip Flexion
Knee extension

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28
Q

What muscles does the femoral nerve innervate?

A

Quadriceps:
Rectus femoris
Vastus medialis/intermedius/lateralis

Sartorius

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29
Q

If the femoral nerve is damaged will hip Flexion be weakened or absent and why?

A

Weakened
Other muscles like Iliacus, Pectineus and psoas major are hip flexors and have other innervations
However, these muscles are mainly innervated by the femoral nerve

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30
Q

If the femoral nerve is damaged will knee extension be weakened or absent and why?

A

Absent

All the muscles which extend the knee supplied by femoral nerve

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31
Q

How can the sciatic nerve be damaged?

A

Compression in gluteal region (Piriformis syndrome)
Iatrogenic (IM injections)
Direct trauma like posterior hip dislocation

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32
Q

What is Piriformis syndrome?

A

The sciatic normal emerges inferior to piriformis or sometimes between piriformis

If the piriformis has spasms it can compress the sciatic nerve

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33
Q

Why can the sciatic be damaged with a posterior hip dislocation?

A

Sciatic close to femur

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34
Q

What is the sensory function of the sciatic?

A

Associated with its branches:
-Common fibular nerve
-Superficial fibular nerve
-Deep fibular nerve
-Tibial nerve

35
Q

What is the motor function of the sciatic nerve?

A

Posterior compartment of thigh (Hamstrings):
-Knee Flexion
-Hip extension

Movement of ankle, mid foot and toes lost due to the more distal tibial and common fibular nerve being affected

36
Q

If the sciatic nerve is damaged will knee Flexion be weakened or absent and why?

A

Absent

Biceps femoris, semitendinosus and Semimembranosus main knee flexors not receiving innervation

Sartorius and Gracilis are knee flexors but aren’t strong enough to do by themselves

37
Q

If the sciatic nerve is damaged will Hip extension be weakened or absent and why?

A

In tact

Gluteus maximus is powerful hip extensor and is innervated by the inferior gluteal nerve

38
Q

What innervates gluteus medius and minimis?

A

Superior gluteal nerve

39
Q

What is the function of gluteus medius and minimis?

A

ABduction
Internal rotation

40
Q

What sign is produced by loss of innervation of the gluteus medius and minimis by the superior gluteal nerve?

A

Trendelenburg sign

41
Q

What is the Trendelenburg sign?

A

Sound side sags when the healthy foot is lifted off the floor

Since contralateral muscles support the pelvis

42
Q

Where does the Tibial nerve run?

A

Branches from the sciatic and runs through the popliteal fossa
Travels between the superficial and deep compartments of the posterior leg
Travels down to the medial malleolus into the foot

43
Q

How can the Tibial nerve be damaged?

A

In the popliteal fossa

Trauma (medial malleolus fracture)

Compression in the tarsal tunnel

44
Q

How can the tibial nerve be damaged in the popliteal fossa?

A

Aneurysm (popliteal artery enlarges)
Popliteal cyst (bakers cyst)
Iatrogenic (knee surgery)
Direct trauma (knife in back of knee)

45
Q

Where is the Tarsal tunnel?

A

Where the nerve runs from the medial malleolus to the heel

46
Q

What is the sensory function of the tibial nerve?

A

Posterilateral leg
Sole of the foot (medial and plantar nerves)
Lateral foot
Heel (medial calcaneal nerve)

47
Q

What is the motor function of the Tibial nerve?

A

Posterior compartment of the leg:
Plantarflexion
Toe Flexion
Inversion

Intrinsic foot muscles

48
Q

If the tibial nerve is damaged will plantarflexion be weakened or absent and why?

A

Absent

Since only the posterior leg muscles do plantarflexion (Tibialis posterior , Gastrocnemius, plantaris and Soleus)

49
Q

If the tibial nerve is damaged will Toe Flexion be weakened or absent and why?

A

Absent

Only flexor hallucis longus and flexor digitorium longus do this

50
Q

If the tibial nerve is damaged will Inversion be weakened or absent and why?

A

Weakened

Since Tibialis anterior is still functional and this is supplied by the DEEP FIBULAR NERVE

51
Q

Damage to motor function really depends on the site of injury, if injury to the Tibial nerve is distal, how may this affect motor function compared to if the damage was proximal?

A

Distal e.g at medial malleolus plantar Flexion unaffected, toe Flexion likely weakened and inversion fine

52
Q

How can the common fibular nerve be damaged?

A

Fibular fracture due to being close to fibular neck (strike to lateral side of leg can cause this)

Compression (plaster cast) due to proximity to fibula

53
Q

What is the sensory function for the common fibular nerve?

A

Small proximal part of lateral leg

54
Q

What is the motor function of the common fibular nerve?

A

No direct motor function
But when it branches to its superficial fibular nerve and deep fibular nerve it has motor function

55
Q

Which nerve supplies the anterior compartment of the leg?

A

Deep fibular nerve

56
Q

Which nerve supplies the lateral compartment of the leg?

A

Superficial fibular nerve

57
Q

What major motor function does the deep fibular never do and what is this called when its absent?

A

Dorsiflexion

Foot drop

58
Q

What nerves will consequently be affected if the common fibular nerve is damaged?

A

Deep/superficial nerves affecting anterior and lateral compartments of leg causing foot drop

59
Q

What can damage the superficial fibular nerve?

A

Direct trauma
Iatrogenic (lateral approach ankle surgery)
Common fibular nerve injury

60
Q

What is the sensory function of the superficial tibial nerve?

A

Anterolateral leg
Dorsum of foot (NOT FIRST WEBBED SPACE THO)

61
Q

What is the motor function of the superficial fibular nerve?

A

Lateral compartment of the leg:
Eversion of the foot

62
Q

If the superficial fibular nerve is damaged is Eversion of the foot weakened or absent?

A

Absent

Fibularis longus and Fibularis brevis are the everters of the foot

62
Q

If the superficial fibular nerve is damaged is Eversion of the foot weakened or absent?

A

Absent

Fibularis longus and Fibularis brevis are the everters of the foot

63
Q

What can damage the deep fibular nerve?

A

Mononeuropathy (it’s a very common peripheral nerve to be affected by other conditions like):

-motor neurons disease
-diabetes
-vasculitis

64
Q

What is the sensory function of the deep fibular nerve?

A

The small 1st webbed space on the Dorsum of the foot (between toes 1 and 2)

65
Q

What is the motor function of the deep fibular nerve?

A

Anterior compartment of leg:
-Dorsiflexion
-Toe extension

66
Q

If the deep fibular nerve is damaged is dorsiflexion of the foot weakened or absent?

A

Absent (foot drop)

Tibialis anterior, extensor hallucis longus, extensor digitorium brevis and Fibularis tertius (if present) are the only dorsiflexors of the foot and they are all innervated by the deep fibular nerve

67
Q

If the deep fibular nerve is damaged is Toe extension of the foot weakened or absent?

A

Absent

Extensor hallucis longus and extensor digitorium longus only toe extenders

68
Q

What are sensory nerves?

A

Nerves that only have sensory function

69
Q

What are 3 sensory nerves in the lower limb?

A

Lateral femoral cutaneous nerve
Sural nerve
Saphenous nerve (branch off femoral nerve forms in femoral triangle)

70
Q

What spinal nerve roots in the lumbosacral plexus contribute to the lateral femoral cutaneous nerve?

A

L2 and L3

71
Q

Where does the lateral femoral cutaneous nerve supply sensation?

A

Anterolateral thigh

72
Q

How can the lateral femoral cutaneous nerve of the thigh be damaged?

A

Compression (tight clothing around waist, belts, pregnancy obesity)

73
Q

What is compression of the lateral femoral cutaneous nerve of the thigh as it exits the pelvis called and what symptoms does it cause?

A

Meralgia paraesthetica

Burning, parasthesia on the anterolateral side of thigh wich worsens with walking/standing

74
Q

What nerves contribute to the formation of the sural nerve?

A

Tibial and common fibular branches

75
Q

What is the sensory distribution of the sural nerve?

A

Lateral ankle/foot
Part of posterior leg

76
Q

What can the sural nerve be used for and why?

A

Nerve grafts
Only has sensory function not motor function

77
Q

What vein is the sural nerve close to?

A

Short saphenous

78
Q

What nerve does the saphenous nerve branch from and where does this branching happen?

A

From femoral nerve
In femoral triangle

79
Q

How can the saphenous nerve be damaged?

A

Iatrogenic damage:
Close to great/long saphenous vein which is often removed in vein grafts

80
Q

What is the sensory functions f the saphenous nerve?

A

Medial leg
Medial border of foot

81
Q

Where is the L4 dermatome?

A

Medial leg runs to the MediaL maLLeoLus

82
Q

Where is the L5 dermatome?

A

Lateral leg inserting onto the dorsum of the foot covering digitis 1,2 and 3

83
Q

What is a way to remember which side of the leg the L4 dermatome is?

A

L4 covers the MediaL maLLeoLus
MediaL maLLeoLus has 4 Ls for L4