MSK - The Common Fibular Nerve

Question 1

What are the nerve roots of the common fibular nerve?

Answer 1

L4-S3

Question 2

What are the motor functions of the common fibular nerve?

Answer 2

Innervates the short head of the biceps femoris directly, also supplies (via branches) the muscles in the lateral and anterior compartments of the leg

Question 3

What are the sensory innervations of the common fibular nerve?

Answer 3

Innervates the skin over the upper lateral and lower posterolateral leg, also supplies (via branches) cutaneous innervation to the skin of the anterolateral leg, and the dorsum of the foot

Question 4

Where does the common fibular nerve begin?

Answer 4

Popliteal fossa, where the sciatic nerve bifurcates into the tibial and common fibular nerves

Question 5

After arising, where does the common fibular nerve follow?

Where does the common fibular nerve give rise to two cutaneous branches?

Answer 5

Follows the medial border of the biceps femoris, running in a lateral and inferior direction, over the lateral head of the gastrocnemius

At this point, the nerve gives rise to two cutaneous branches, which contribute to the innervation of the skin of the leg

Question 6

How does the common fibular nerve enter the lateral compartment of the leg, and how does it finally terminate?

Answer 6

Nerve wraps around the neck of the fibula, passing between the attachments of the fibularis longus

Here, the common fibular nerve terminates by dividing into the superficial fibular and deep fibular nerves

Question 7

What part of the biceps femoris muscle does the common fibular nerve innervate?

Answer 7

The short head of the biceps femoris

Question 8

In addition, its terminal branches also provide innervation to muscles

What is the motor innervations of the superficial fibular nerve?

Answer 8

Muscles of the lateral compartment of the leg;

Fibularis longus and brevis

These muscles act to evert the foot

Question 9

In addition, its terminal branches also provide innervation to muscles

What are the motor innervations of the deep fibular nerve?

Answer 9

Muscles of the anterior compartment of the leg;

Tibialis anterior

Extensor digitorum longus

Extensor hallucius longus

These muscles act to dorsiflex the foot, and extend the digits. It also innervates some intrinsic muscles of the foot

Question 10

If the common fibular nerve is damaged, what actions might be lost?

Answer 10

Loss of the ability to dorsiflex and evert the foot, and extend the digits

Question 11

What are the two cutaneous branches that arise from the common fibular nerve as it passes over the gastrocnemius?

Answer 11

Sural commicating nerve

Lateral sural cutaneous neve

Question 12

The sural commicating nerve combines with a branch of the tibial nerve to form what nerve?

What does this nerve innervate?

Answer 12

Sural Nerve

The sural nerve innervates the skin over the lower posterolateral leg

Question 13

What does the lateral sural cutaneous nerve innervate?

Answer 13

Skin over the upper lateral leg

Question 14

What are the terminal branches of the common fibular nerve?

Answer 14

Superficial fibular nerve

Deep fibular nerve

Question 15

The terminal branches of the common fibular nerve also have a cutaneous function

What is the cutaneous function of the Superficial Fibular Nerve?

Answer 15

Innervates the skin of the anterolateral leg, and dorsum of the foot (except the skin between the first and second toes)

Question 16

The terminal branches of the common fibular nerve also have a cutaneous function

What is the cutaneous function of the deep fibular nerve?

Answer 16

Innervates the skin between the first and second toes

Question 17

Label the cutaneous innervation of the leg

Answer 17

Question 18

How is the common fibular nerve most commonly damaged by?

Answer 18

Fracture of the fibula, or the use of a tight plaster cast

Question 19

How will patients with common fibular nerve damage present in relation of motor function?

Answer 19

Lose the ability to dorsiflex the foot at the ankle joint. Hence the foot will appear permanently plantarflexed – known as footdrop. They may also present with a characteristic gait, as a result of the footdrop

Question 20

How will patients with common fibular nerve damage present clinically in term of sensory function?

Answer 20

Loss of sensation over the dorsum of the foot, and lateral side of the leg. Innervation is preserved on the medial side of the leg (supplied by the saphenous nerve, a branch of the femoral), and the heel and sole (supplied by the tibial nerve, a branch of the sciatic)