Deep Fibular Nerve

Question 1

What is the deep fibular nerve?

Answer 1

One of the terminal branches of the common fibular nerve

Question 2

What are the nerve roots of the deep fibular nerve?

Answer 2

L4 and L5

Question 3

What are the motor functions of the deep fibular nerve?

Answer 3

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

Question 4

What are the sensory functions of the deep fibular nerve?

Answer 4

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

Question 5

How does the deep fibular nerve originate?

Answer 5

The sciatic nerve bifurcates into the common fibular and the tibial nerves at the apex of the popliteal fossa, at the back of the knee. The common fibular nerve wraps around the neck of the fibula, moving anterolaterally, and gives rise to the two terminal branches- superficial and deep fibular nerve

Question 6

Where does the deep fibular nerve arise?

Answer 6

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

Question 7

What is the anatomical course of the deep fibular nerve?

Answer 7

The nerve moves from the lateral compartment to the anterior compartment of the leg. It then follows the course of the anterior tibial artery, in an inferomedial direction. Together, the two structures pass between the tibialis anterior and the extensor digitorum longus in the superior portion of the leg, and between the tibialis anterior and the extensor hallucis longus in the inferior leg
The deep fibular nerve crosses the ankle joint, passing anterior to the distal tibia, and travels deep to the extensor retinaculum

Question 8

Where does the deep fibular nerve terminate?

Answer 8

In the dorsum of the foot

Question 9

How does the deep fibular nerve terminate?

Answer 9

It divides into a lateral branch and a medial branch do

Question 10

What does the lateral branch of the deep fibular nerve do?

Answer 10

Supplies motor innervation to some of the intrinsic muscles of the foot

Question 11

What does the medial branch of the deep fibular nerve do?

Answer 11

Innervates the skin between the 1st and 2nd toes

Question 12

Where are the muscles that the deep fibular nerve innervates found?

Answer 12

In the anterior compartment of the leg

Some intrinsic muscles of foot

Question 13

What muscles of the anterior leg does the deep fibular nerve innervate?

Answer 13

Tibialis anterior
Extensor halucis longus
Extensor digitorum longus
Fibularis tertius

Question 14

What are the muscles of the anterior leg innervated by the deep fibular nerve responsible for?

Answer 14

Dorsiflexion of the foot

Question 15

When is dorsiflexion of the foot required during the gait cycle for walking?

Answer 15

When a person strikes their heel on the floor in the stance phase
During the swing phase

Question 16

Which intrinsic muscles of the foot are innervated by the deep fibular nerve?

Answer 16

The extensor digitorum brevis and extensor hallucis brevis

Question 17

What are the intrinsic foot muscles innervated by the deep fibular nerve responsible for?

Answer 17

Extending the toes at the metatarsophalangeal joints and interphalangeal joints

Question 18

Where does the deep fibular nerve terminate?

Answer 18

In the dorsum of the foot as the cutaneous nerve

Question 19

What does the cutaneous nerve of the deep fibular nerve innervate?

Answer 19

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

Question 20

When can the deep fibular nerve become entrapped or compressed?

Answer 20

During its course through the anterior compartment of the leg

Question 21

What does entrapment or compression of the deep fibular nerve cause?

Answer 21

Paralysis of the muscles in the anterior compartment of the leg, and so a patient loses the ability to dorsiflex the foot

Question 22

What happens with unopposed plantarflexion?

Answer 22

The foot drops

Question 23

What does footdrop give?

Answer 23

The patien’t foot difficulty in clearing the ground during the swing phase of walking, and the limb looks too long
The foot will slap down on the floor when the patient walks, because it can’t be lowered in a controlled manner

Question 24

How is footdrop compensated for when walking?

Answer 24

The patient develops an abnormal gait

Question 25

What abnormal gaits may arise from footdrop?

Answer 25

Waddling gait
Swing-out gait
High steppage gait

Question 26

What happens in waddling gait?

Answer 26

The patient leans excessively onto the normal limb

Question 27

What is swing-out gait?

Answer 27

The patient abducts the abnormal limb

Question 28

What is high-steppage gait?

Answer 28

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

Question 29

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

Answer 29

Anterior leg muscles may have been excessively used, and so are compressing the nerve within the anterior compartment
Tight-fitting shoes may compress the nerve beneath the extensor retinaculum

Question 30

What will the patient experience when the deep fibular nerve is compressed because of excessive anterior leg muscle usage?

Answer 30

Pain the anterior leg

Question 31

What will the patient experience when the deep fibular nerve is compressed because tight fitting shoes?

Answer 31

Pain in the dorsum of the foot