Lower Extremity Nerves

Question 1

What dermatome does the obturator nerve innervate?

Answer 1

L2-L4

Question 2

What causes injury to the obturator nerve?

Answer 2

1. Pelvic Surgery

Question 3

What is the presentation of an obturator nerve injury?

Answer 3

Decrease thigh sensation medially and decrease adduction

Question 4

What dermatome does the femoral nerve innervate?

Answer 4

L2-L4

Question 5

What causes injury to the femoral nerve?

Answer 5

1. Pelvic Surgery

Question 6

What is the presentation of a femoral nerve injury?

Answer 6

1. Decreased thigh flexion

2. Decreased thigh extension

Question 7

What dermatome does the common peroneal nerve innervate?

Answer 7

L4-S2

Question 8

What causes injury to the common peroneal nerve?

Answer 8

1. Trauma or compression of the lateral aspect of the leg

2. Fibular neck fracture

Question 9

What is the presentation of a common peroneal nerve injury?

Answer 9

1. Foot drop: inverted and plantarflexed at rest, loss of eversion and dorsiflexion
2. Steppage gait: loss of sensation on dorsum of foot

Question 10

What dermatome does the tibial nerve innervate?

Answer 10

L4-S3

Question 11

What causes injury to the tibial nerve?

Answer 11

1. Knee trauma
2. Baker cyst (proximal lesion)
3. tarsal tunnel syndrome (distal lesion)

Question 12

What is the presentation of a tibial nerve injury?

Answer 12

1. Inability to curl toes
2. Loss of sensation on sole of the foot
3. In proximal lesions due to a baker cyst, foot is everted at rest with loss of inversion and plantarflexion.

Question 13

What dermatome does the superior gluteal nerve innervate?

Answer 13

L4-S1

Question 14

What causes injury to the superior gluteal nerve?

Answer 14

Iatrogenic due to intramuscular injection to the upper medial gluteal cleft

Question 15

What is the presentation of a superior gluteal nerve injury?

Answer 15

1. Trendelenburg sign/Giat: pelvis tilts because weight-bearing leg cannot maintain alignment of pelvis through hip abduction.

The lesion is contralateral to the side of the hip that drops, ipsilateral to the extremity on which the patient stangs.

Question 16

What dermatomes does the inferior gluteal nerve innervate?

Answer 16

L5-S2

Question 17

What causes injury to the inferior gluteal nerve?

Answer 17

1. Posterior hip dislocation

Question 18

What is the presentation of an inferior gluteal nerve injury?

Answer 18

1. Difficulty climbing stairs
2. Difficulty rising from a seated position
3. Loss of hip extension

Question 19

What muscles does the superior gluteal nerve innervate?

Answer 19

1. gluteus medius
2. gluteus minimus
3. tensor fascia latae

Question 20

What muscles does the inferior gluteal nerve innervate?

Answer 20

1. gluteus maximus

Question 21

What is the function of the Peroneal nerve?

Recall PED

Answer 21

The peroneal nerve everts and dorsiflexes the foot.

If injured, the foot is dropPED.

Question 22

What is the function of the tibial nerve?

Recall TIP

Answer 22

The tibial nerve inverts, and plantarflexes the foot.

If injured, the patient cannot stand on TIPtoes.

Question 23

What does the pudendal nerve innervates?

Answer 23

Perineum

Question 24

How is the pudendal nerve blocked?

Answer 24

The pudendal nerve can be blocked with local anesthesia during childbirth using the ischial spine as a landmark for injection

Question 25

What is the site to inject in the buttocks to avoid nerve injury?

Answer 25

Choose the superolateral gluteal quadrant to avoid nerve injury.