MSK - The Deep Fibular Nerve

Question 1

What are the nerve roots of the deep fibular nerve?

Answer 1

L4 and L5

Question 2

What are the motor functions of the deep fibular nerve?

Answer 2

Innervates the muscles in the anterior compartment of the leg, as well as some of the intrinsic muscles of the foot

Question 3

What are the sensory functions of the deep fibular nerve?

Answer 3

Supplies the triangular region of skin between the 1st and 2nd toes

Question 4

From what nerve does the deep fibular nerve arise from?

Answer 4

Common Fibular Nerve

Question 5

Where does the deep fibular nerve arise?

Answer 5

In the superolateral aspect of the leg, between the fibularis longus muscle and the neck of the fibula

Question 6

From what compartment does the deep fibular nerve move from and to which compartment does the deep fibular nerve travel to?

Answer 6

Moves from the lateral compartment to the anterior compartment of the leg

Question 7

The deep fibular nerve follows the course of what vascular structure through the leg?

Answer 7

Anterior tibial artery

Question 8

With the anterior tibial artery, the deep fibular nerve pass between what two muscles in the superior part of the leg and what two muscles in the inferior part of the leg?

Answer 8

Superior - Tibialis anterior and Extensor digitorum longus

Inferior - Tibialis anterior and the Extensor hallucis longus

Question 9

The deep fibular nerve crosses what joint?

What direction does it pass the distal tibia?

Into what does it travel?

Answer 9

Crosses the ankle joint

Anterior

Extensor Retinaculum

Question 10

How and where does the deep fibular nerve terminate?

Answer 10

In the dorsum of the foot, where it divides into a lateral and medial branch

Question 11

What is the motor function of the lateral branch of the deep fibular nerve after it terminates?

What is the cutaneous function of the medial branch of the deep fibular nerve after it terminates?

Answer 11

Some of the intrinsic muscles of the foot

Skin between the 1st and 2nd toes

Question 12

The deep fibular nerve innervates what muscles in the anterior compartment of the leg?

What are these muscles responsible for?

Answer 12

Tibialis anterior

Extensor halucis longus

Extensor digitorum longus

Fibularis tertius

Dorsiflexion of the foot

Question 13

During what parts of the gait cycle for walking is dorsiflexion required?

Answer 13

1 - When a person strikes their heel on the floor in the stance phase

2 - During the swing phase

Question 14

What intrinsic muscle of the foot does the deep fibular nerve innervate?

What are these muscles responsible for?

Answer 14

Extensor digitorum brevis

Extensor hallucis brevis

Extending the toes at the metatarsophalangeal joints and interphalangeal joints

Question 15

Where and as what does the deep fibular nerve terminate?

What part of the skin does it innervate?

Answer 15

Dorsum of the foot as a cutaneous nerve

Webbed space of skin between the great toe (hallux) and the second toe

Question 16

What would compression or entrampment of the deep fibular nerve clinically present?

Answer 16

Paralysis of the muscles in the anterior compartment of the leg

Loss of the ability to dorsiflex the foot

Question 17

With unopposed plantarflexion, their foot drops

Describe the appearance of characteristic of foot drop

Answer 17

Gives the patient’s foot difficulty in clearing the ground during the swing phase of walking

Limb looks too long

Foot will slap down on the floor when the patient walks, because it can’t be lowered in a controlled manner.

Question 18

How does a patient compensate for foot drop?

Answer 18

Develops an abnormal gait

Question 19

What are the three abnormal gaits that can be developed to compensate for foot drop?

Describe them

Answer 19

Waddling gait - The patient leans excessively onto the normal limb

Swing-out gait - The patient abducts the abnormal limb

High steppage gait - The patient flexes the hip and knee excessively on the abnormal limb, so as to clear the dropped foot from the floor

Question 20

What are the two main reasons that the deep fibular nerve could be compressed?

Answer 20

1 - Anterior leg muscles have been excessively used and so are compressing the nerve within the anterior compartment, the patient will experience pain in the anterior leg

**2 - ** Tight-fitting shoes, compressing the nerve beneath the extensor retinaculum. This commonly occurs with wearing tight ski boots (referred to asski boot syndrome). The patient will experience pain in the dorsum of the foot