Nerve Lesions of Lower LImb

Question 1

The knee cannot be extended in a patient! What nerve is injured?

Answer 1

Femoral nerve (supplies quadriceps femoris)

Question 2

Which fibers of the sciatic nerve lie most superficial? Why is this significant?

Answer 2

Common fibular nerve - it is most affected by sciatic nerve lesions

Question 3

The sciatic nerve is lesioned in an intramuscular injection in the gluteal region. What muscles in the posterior thigh are paralyzed?

Answer 3

Hamstring muscles - flex the knee/leg

Question 4

Why is flexion at the knee still possible in a lesion of the sciatic nerve?

Answer 4

Action of sartorius (which also flexes at the hip) and gracilis (which also adducts the thigh)

Question 5

The sciatic nerve is lesioned in an intramuscular injection in the gluteal region. What muscles in the leg are paralyzed?

Answer 5

All muscles below the knee.

Question 6

The sciatic nerve is lesioned in an intramuscular injection in the gluteal region. What does the foot look like now?

Answer 6

Foot is plantar-flexed (“foot drop”)

Question 7

A nerve is trapped in the callus that forms on the fibular neck. What does the foot do as a result of the loss of this nerve?

Answer 7

Foot is plantar-flexed (foot drop) and inverted (Equinovarius)
(Loss of anterior/lateral compartments means no dorsiflexion and eversion)

Question 8

In a tibial nerve lesion, what will the foot do after the corresponding muscles are paralyzed?

Answer 8

Foot is dorsiflexed and everted (Calcaneovalgus)

Question 9

Anterior dislocations of the hip joint cause possible loss of what nerve?

Answer 9

Obturator

Question 10

Anterior dislocations of the hip joint may result in the inability to perform what action?

Answer 10

Adduction of thigh, via obturator nerve lesion

Question 11

Posterior dislocations of the hip joint may result in the loss of what nerve?

Answer 11

Sciatic nerve