Nerve injuries to the lower limb

Question 1

What would be result of common peroneal (fibular) nerve (bit before it divides into superficial and deep, around knee joint) injury?

Answer 1

• foot drop (loss of dorsiflexion

- loss of sensation on lateral calf and dorsum of foot

Question 2

which area of skin does the sural nerve innervate? (it has no motor functions)

Answer 2

lateral sole of foot and posteriolateral aspect of calf

Question 3

What would be the result of a superficial peroneal (fibular nerve) injury?

Answer 3

weakness in eversion

loss of sensation to dorsum of foot and lower, anteriolateral aspect of lower leg

Question 4

When can sural nerve be damaged?

Answer 4

• surgery to posterior ankle eg for achilles tendon rupture

- also commonly used as nerve graft

Question 5

What is the result of a deep peroneal nerve injury?

Answer 5

loss of dorsiflexors (tibialis anterior, extensor hallucis longus, extensor digitoum longus)–> foot drop
sensory loss of 1st webspace
- upper anteriolateral aspect of lower leg still has sensation as this is supplied by the common peroneal nerve

Question 6

What are the 3 seddon levels of nerve injury?

Answer 6

Neurapraxia
axonotmesis
neurotmesis

Question 7

Which area of the leg does the saphenous nerve innervate?

Answer 7

the anteriomedial aspect below the knee to the ankles

Question 8

Which movements does the obturator control?

Answer 8

thigh adduction (adductor longus, brevis and magnus)

Question 9

Where does the sciatic nerve go?

Answer 9

exits sciatic notch below to piriformis muscle but in front of the short external rotators then goes behind biceps femoris

Question 10

Describe the dermatomes of the lower limb

Answer 10

• top front is L1
• L2 is thigh
• L3 is knee
• L4 inner calf
• L5 outer calf and top of foot
• S1 little toe and sole of foot
• S2 back of all of leg
• S3 buttocks

Question 11

What can cause a superifical peroneal (fibular) nerve injury?

Answer 11

ankle fractures

ankle surgery

Question 12

Describe the 3 seddon levels of nerve injury

Answer 12

Neurapraxia- a conduction block in the axon meaning signals arnt transmitted properly. axons are still in tact however. this is caused by pressure or stretching.
Axonotmesis- axon is broken by myelin is still in tact so axon can regrow
Neurotmesis- axon, swchann cell and endoneurium completely divided, potential for regrowth unpredictable

Question 13

What is piriformis syndrome?

Answer 13

sciatic symptoms (buttock pain/ pain down leg) due to overuse of the piriformis muscle leading it to spasm and put pressure on the sciatic nerve

Question 14

How do you commonly damage the common peroneal nerve?

Answer 14

Blow to outside side of knee- hit by car

Question 15

How can the saphenous nerve commonly be damaged?

Answer 15

during surgery of stripping of saphenous vein varicosities

Question 16

What is meralgia paraesthetica?

Answer 16

compression of the lateral cutaneous nerve as it passes through the inguinal ligament or as it pierces the fascia lata

Question 17

What causes meralgia paraesthetica?

Answer 17

compression by abdo fat (obesity), pregnancy, tight clothing, wearing tool belt

Question 18

What is result of tibial nerve injury?

Answer 18

loss of planterflexion and inversion leads to foot permenantly everted and dorsiflexed- calcaneovalgus foot
loss of sensation on sole of foot

Question 19

Which movements does the common fibular nerve control?

Answer 19

the toe extensors and dorsiflexors

Question 20

What are the clinical features of meralgia paraesthetica?

Answer 20

burning or stinging sensation of anteriolateral aspect of thigh, made worse by walking or standing and relieved by lying down with hip flexed.
tenderness on palpation with reduced sensation.
no motor control loss

Question 21

What is the name of the system for classifying nerve injuries?

Answer 21

the seddon classification