Lower limb - nerves

Question 1

In a patient with traumatic damage to the femoral nerve at the level of the inguinal ligament, why would sensation be preserved over the lateral thigh?

Answer 1

The lateral cutaneous nerve does not originate from the femoral nerve, so will be unaffected.

Question 2

What are the nerve roots of the sciatic nerve?

Answer 2

L4-S3

Question 3

What are the nerve roots of the obturator nerve and femoral nerve?

Answer 3

L2-L4

Question 4

What are the nerve roots of the superior gluteal nerve?

Answer 4

L4, L5 and S1

Question 5

What are the nerve roots of the inferior gluteal nerve?

Answer 5

L5, S1 and S2

Question 6

What motor functions would be affected by damage to the femoral nerve?

Answer 6

Loss of hip flexion and knee extension

Question 7

What sensory effects would you see if the femoral nerve is damaged?

Answer 7

Loss of sensation in anterior thigh and medial leg (saphenous stems from femoral)

Question 8

What motor signs would you expect to see if the obturator nerve is damaged?

Answer 8

Loss of adduction of thigh

Question 9

What sensory signs would you expect to see if the obturator nerve is damaged?

Answer 9

Loss of sensation inner thigh

Question 10

What would you expect to see if the inferior gluteal nerve is damaged?

Answer 10

Loss of extension of hip

Buttock wasting

Question 11

What motor functions would be compromised if the sciatic nerve is damaged?

Answer 11

Loss of all except adduction and flexion of thigh and extension of knee

Question 12

What sensory problems would you see if the sciatic nerve is damaged?

Answer 12

Loss of sensation lateral leg and foot

Question 13

What motor sign would you expect to see if the common fibular nerve is damaged?

Answer 13

Loss of extension of toes and foot (foot drop)

Question 14

What sensory changes would you see if the common fibular nerve is damaged?

Answer 14

Lossof sensation over lateral lower leg and upper foot

Question 15

What motor problems would you see if the tibial nerve was damaged?

Answer 15

Loss of plantar flexion, loss of flexion of toes and weakened inversion (tibialis anterior can still invert)

Question 16

Name the artery that accompanies the sciatic nerve as it exits posterior to the piriformis muscle.

Answer 16

Inferior gluteal artery

Question 17

If the sciatic nerve is damaged inferior to the point that it leaves the pelvis, will hip extension be present, absent or compromised?

Answer 17

Compromised - as gluteus maximus is mostly unaffected

Question 18

Will knee flexion and dorsiflexion be present or absent after damage to the sciatic nerve?

Answer 18

Absent

Question 19

What is the name given to nerve injury when axons distal to the injury undergo degeneration.

Answer 19

Wallerian degeneration

Question 20

What is a traumatic neuroma?

Answer 20

A lesion that occurs after a nerve has been severed when there is poor alignment of the cut ends of the nerves.
A disordered proliferation of axons resulting in a tangled mass

Question 21

Apart from a nodule, what is the commonest symptom associated with a neuroma?

Answer 21

Pain!

Question 22

What is the most common mechanism of saphenous nerve injury?

Answer 22

Operation stripping of long saphenous vein - nerve accompanies vein

Question 23

What symptom is present if the saphenous nerve is damaged?

Answer 23

Loss of sensation over medial leg

Question 24

What sensory loss if the deep peroneal nerve is damaged?

Answer 24

1st web space

Question 25

What sensory loss would you see if the superficial peroneal nerve is damaged?

Answer 25

Sensory loss over most of skin of dorsum of foot (not first web space) and anterolateral calf

Question 26

What is the course of the gluteal nerves?

Answer 26

Leave pelvis via greater sciatic foramen.

Superior gluteal nerve passes superior to piriformis muscle and inferior gluteal nerve passes inferior to piriformis.