Common Fibular Nerve: The common fibular nerve, further known as the common peroneal nerve, is one of two main branches of the sciatic nerve. Common fibular nerve later divides into the deep and superficial fibular nerves.
Nerve roots: L4 – S3
Motor: Innervates the short head of the biceps femoris muscle directly. Additionally, supplies (via branches) the muscles in the lateral and anterior compartments of the leg muscles.
Sensory: Innervates the skin over the upper lateral and lower posterolateral of the leg. Further supplies (via branches) cutaneous innervation to the skin of the anterolateral leg, and the dorsum of the foot.
Anatomical Course of the Common Fibular Nerve
The nerve starts at the apex of the popliteal fossa, where the sciatic nerve bifurcates toward the tibial and common fibular nerves.
The common fibular nerve follows the medial border of the biceps femoris muscle, traveling in a lateral and inferior direction, over the lateral head of the gastrocnemius muscle. At the point, the nerve gives rise to two cutaneous branches, that contribute to the innervation of the skin of the leg.
To penetrate the lateral compartment of the leg, the nerve wraps nearby the neck of the fibula, passing within the attachments of the fibularis longus muscle. Here, the common fibular nerve ends by dividing into the superficial fibular and deep fibular nerves.
Function of the Common Fibular Nerve
The common fibular nerve supplies the short head of the biceps femoris muscle (part of the hamstring muscles, that flex the knee joint)
In addition, its terminal branches also contribute innervation to muscles:
- Superficial fibular nerve: Innervates the muscles of the lateral compartment of the leg; fibularis longus and brevis muscle. Those muscles act to evert the foot.
- Deep fibular nerve: Supplies the muscles of the anterior compartment of the leg; tibialis anterior, extensor hallucis longus and extensor digitorum longus . Those muscles work to dorsiflex the foot and extend the digits. It further innervates some intrinsic muscles of the foot.
If the common fibular nerve is injured, the patient may lose the capability to dorsiflex and evert the foot and extend the digits.
There are two cutaneous branches that emerge directly from the common fibular nerve as it moves over the lateral head of the gastrocnemius muscle.
- Lateral sural cutaneous nerve: Supplies the skin over the upper lateral leg.
- Sural communicating nerve: This nerve connects with a branch of the tibial nerve to form the sural nerve. The sural nerve supplies the skin over the lower posterolateral leg.
In addition to these nerves, the terminal branches of the common fibular nerve further have a cutaneous function:
- Superficial fibular nerve: Supplies the skin of the anterolateral leg, and dorsum of the foot (except the skin among the first and second toes).
- Deep fibular nerve: Innervates the skin among the first and second toes.