The Anatomy of the Superficial Peroneal Nerve

Provides motor and sensory function in the calf and foot

In This Article

A woman's calf is colored red along the outside, where the superficial peroneal nerve runs.

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The superficial peroneal nerve, also called the superficial fibular nerve, is a peripheral nerve of the calf. It's a terminal branch of the common peroneal nerve, which itself is a branch of the sciatic nerve. The superficial peroneal nerve contains both motor and sensory fibers, meaning it provides both motion and sensation.

Anatomy

Most of the nerves in your body branch off from the spinal cord. The nerves that extend away from the spine and into the limbs are called peripheral nerves. As the peripheral nerves make their way through the limbs, they send off branches that connect to various tissues to provide them with motor function, sensory function, or both.

The sciatic nerve's roots leave the spinal cord through the spaces between the vertebrae in the lumbar and sacral regions of the lower spine. The roots then combine into a single nerve (one on each side) and run down through the buttocks and the back of your thigh.

As the sciatic nerve reaches the back of your knee, which is called the popliteal fossa, it separates into two main branches:

  1. The tibial nerve, which is primarily a motor nerve
  2. The common peroneal nerve, which is primarily a sensory nerve

The tibial nerve continues down the back of the leg while the common peroneal nerve wraps around the outside of the knee to reach the front of your calf. Not far below the knee, the common peroneal nerve divides into its two terminal branches:

  1. The deep peroneal nerve
  2. The superficial peroneal nerve

Structure

The superficial peroneal nerve sends off motor branches to the fibularis longus and fibularis brevis muscles and cutaneous (meaning of the skin) sensory branches to a portion of the lower leg. It then splits into two more cutaneous sensory branches called:

  1. Medial dorsal cutaneous nerve
  2. Intermedial dorsal cutaneous nerve

Those are the terminal branches of the nerve.

Location

From where the superficial peroneal nerve gets its start at the neck of the fibula, which is the bone on the outside of your calf, it runs down between the fibularis muscles and the outside of the extensor digitorum longus muscle. That's where it branches off to the muscles along the outside of the leg.

Continuing its journey down the leg, it connects to the skin on the right front quadrant of your calf.

Once the superficial peroneal nerve gets down toward the ankle, it goes through connective tissue called the deep crural fascia, which holds the tendons of the lower leg in place. That's where it divides into the medial and intermedial dorsal cutaneous branches.

Function

Early on in its journey, the superficial peroneal nerve plays a role in motor function of the muscles. Farther down, its role becomes purely sensory and cutaneous.

Motor Function

The muscles the superficial peroneal nerve innervates are:

  • Peroneus longus
  • Peroneus brevis

These muscles work with the subtalar joint just below your ankle to allow you to rotate the tips of your feet outward. They also have some involvement with plantar flexion (pointing your toes), although this motion is mostly due to the action of the gastrocnemius and soleus muscles in the back of your calf.

Working with the deep peroneal nerve, the superficial branch also provides motor function to the extensor digitorum brevis.

Sensory Function

Below the branches to the peroneus longus and brevis muscles, the superficial peroneal nerve becomes sensory only. It provides feeling to:

  • The skin of the right front quadrant of your calf
  • By way of the medial and intermedial dorsal cutaneous nerves, the skin across most of the top of your foot

One small spot—between the first and second toes—is the only part of the top of the foot not innervated by the superficial peroneal nerve. It receives feeling via the deep peroneal nerve, instead.

Associated Conditions

Superficial peroneal nerve damage and entrapment are both somewhat common.

Nerve Damage

The nerve can be damaged by injury due to any kind of trauma along its course or by diseases such as:

Symptoms of neuropathy (nerve damage) in the superficial peroneal nerve may include:

  • Pain in the calf or foot
  • Decreased sensation, numbness, or tingling in the skin innervated by this nerve or its branches
  • Weakness in the foot and ankle due to loss of function in the muscles innervated by this nerve or its branches
  • Loss of muscle mass due to lack of nerve stimulation

Neuropathy can be diagnosed using a variety of methods generally selected due to specific symptoms and suspected causes. Diagnostic methods include:

Nerve Entrapment

Superficial peroneal nerve entrapment can result from fascial swelling or dysfunction where the nerve runs through the deep crural fascia near the ankle, which can result from injury. Ankle sprains and twists can also lead to entrapment from the nerve becoming over-stretched.

Symptoms of entrapment include:

  • Pain
  • Abnormal sensation (paresthesia) such as tingling or burning

Rehabilitation

In cases of nerve damage or entrapment, the typical approach is to treat the underlying injury or disease. Other options include:

  • Physical therapy, to improve muscle strength
  • Occupational therapy, to improve mobility and function
  • Braces, splints, orthopedic shoes, or other equipment to help you walk

Over-the-counter pain medications may help ease the symptoms. If they don't provide enough relief, your doctor may prescribe other medications for nerve pain, including:

In cases of severe pain, you may want to see a pain specialist.

Surgery may be an option in cases where:

  • Entrapment is caused by the deep crural fascia
  • Movement is seriously impaired
  • Treating the underlying cause doesn't relieve the neuropathy
  • The nerve axon is damaged
  • Something (such as a tumor or growth) is putting pressure on the nerve
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