The human body is a marvel of integrated systems that enable us to move, feel, and interact with our environment. Each part has a specific function and depends on others to work properly. One such crucial component is the peroneal nerve, which powers the muscles and senses of the foot and ankle. Understanding the anatomy, physiology, and pathology of this nerve can help us appreciate its role in our daily activities and how to care for it.
Anatomy of the Peroneal Nerve
The peroneal nerve is part of the peripheral nervous system, which connects the brain and spinal cord to the limbs and organs. It arises from the sciatic nerve, which originates from the lower back and runs down the thigh. The peroneal nerve splits from the sciatic nerve near the knee joint and descends along the outer side of the leg and the ankle. It divides into two branches: the superficial and deep peroneal nerves.
The superficial peroneal nerve innervates the skin and muscles on the front and outer side of the leg and the dorsum (top) of the foot. The deep peroneal nerve supplies the muscles on the front and inner side of the leg and the dorsum of the foot. It also provides sensory input to the first web space (between the big and second toes) and the distal (far) parts of the dorsal foot.
The peroneal nerve works in concert with other nerves, muscles, bones, and ligaments to enable various movements of the foot and ankle, such as dorsiflexion (lifting the foot and toes up), inversion (turning the foot and toes inward), and eversion (turning the foot and toes outward). It also helps maintain balance and proprioception (sense of where the foot is in space).
Physiology of the Peroneal Nerve
The peroneal nerve is commonly classified as a mixed nerve, meaning it contains both sensory and motor fibers. The sensory fibers convey information about touch, pressure, temperature, and pain from the skin and joints of the foot and ankle to the spinal cord and brain. The motor fibers control the contraction and relaxation of the muscles of the foot and ankle.
The peroneal nerve can be affected by various factors that interfere with its function. For example, compression or stretching of the nerve can cause symptoms such as pain, numbness, tingling, weakness, or clumsiness of the foot and ankle. Trauma, inflammation, infection, tumors, or systemic diseases can also damage the nerve and impair its signals. Understanding the signs and symptoms of peroneal nerve injury can facilitate diagnosis and treatment.
Signs and Symptoms of Peroneal Nerve Injury
- Pain or burning sensation on the outer side of the knee or the top or the bottom of the foot
- Numbness, tingling, or loss of sensation in the first web space or the distal dorsal foot
- Weakening or paralysis of the muscles that lift the foot and toes up or turn the foot and toes outward
- Dropping of the foot and toes down (foot drop) or turning of the foot and toes inward (inverted foot)
- Difficulty walking or balancing, especially on uneven or tilted surfaces
Pathology of the Peroneal Nerve
The peroneal nerve can be affected by various disorders that affect its structure or function. Some of the most common conditions are:
Peroneal Nerve Entrapment
Peroneal nerve entrapment occurs when the nerve is compressed or pinched by surrounding structures, such as muscles, bones, or ligaments. The most common sites of compression are the fibular head (where the nerve divides into its branches) and the lateral ankle (where the nerve runs along the ankle bones). The causes of entrapment can vary, including trauma, repetitive movements, tight footwear or clothing, or anatomical variations.
The symptoms of peroneal nerve entrapment can range from mild and intermittent to severe and constant, depending on the severity and duration of the compression. Treatment may involve rest, immobilization, physical therapy, medication, or surgery.
Peroneal neuropathy refers to any injury or disorder that affects the peroneal nerve, regardless of the underlying cause. Some common causes of peroneal neuropathy are trauma, diabetes, alcoholism, infections, tumors, and autoimmune diseases. The symptoms may resemble those of entrapment, but may involve more widespread areas or systemic effects.
The diagnosis of peroneal neuropathy may involve various tests, such as electromyography, nerve conduction studies, imaging, and blood tests. Treatment may depend on the underlying cause and the severity of the symptoms, and may involve a combination of medications, physical therapy, braces, splints, or surgery.
Peroneal tendonitis is a condition that affects the tendons that attach the peroneal muscles to the bones of the foot and ankle. The tendons can become inflamed, stretched, or torn due to overuse, trauma, or biomechanical imbalances. The symptoms may include pain, swelling, and weakness in the affected area, as well as difficulty moving the foot and ankle properly.
The treatment of peroneal tendonitis may involve rest, ice, compression, elevation, medication, physical therapy, or surgery.
Care of the Peroneal Nerve
The peroneal nerve, like other parts of the body, can benefit from appropriate care and prevention of injury. Some tips on how to maintain the health and function of the peroneal nerve are:
- Wear appropriate footwear that fits well, provides cushioning, support, and stability, and avoids excessive pressure or friction on sensitive areas.
- Warm up and stretch before exercising, especially if you engage in activities that involve repetitive or high-impact movements of the foot and ankle.
- Avoid sudden or excessive twisting, bending, or stretching of the foot and ankle, especially if you have a history of joint problems or muscle weakness.
- Maintain a healthy lifestyle that includes proper nutrition, hydration, rest, and exercise to reduce the risk of systemic diseases that can affect nerve function.
- Follow your healthcare provider’s recommendations for managing any pre-existing conditions that may increase your risk of peroneal nerve injury.
The peroneal nerve is a vital component of foot and ankle mobility and sensation. Understanding its anatomy, physiology, and pathology can help us appreciate its importance and take care of it better. By following some simple preventive measures and seeking prompt medical attention when needed, we can minimize the risk of peroneal nerve injury and maximize the benefits of its function.
Questions and Answers
- What is the peroneal nerve?
- The peroneal nerve is a nerve that powers the muscles and senses of the foot and ankle.
- Where does the peroneal nerve come from?
- The peroneal nerve arises from the sciatic nerve, which originates from the lower back and runs down the thigh.
- What does the peroneal nerve do?
- The peroneal nerve helps enable various movements of the foot and ankle, such as dorsiflexion (lifting the foot and toes up), inversion (turning the foot and toes inward), and eversion (turning the foot and toes outward). It also helps maintain balance and proprioception (sense of where the foot is in space).
- What causes peroneal nerve injury?
- Peroneal nerve injury can be caused by compression, stretching, trauma, inflammation, infection, tumors, or systemic diseases.
- What are the symptoms of peroneal nerve injury?
- The symptoms of peroneal nerve injury can include pain, numbness, tingling, weakness, or clumsiness of the foot and ankle, as well as difficulty walking or balancing.
- How is peroneal nerve injury treated?
- The treatment of peroneal nerve injury may depend on the underlying cause and the severity of the symptoms, and may involve rest, immobilization, physical therapy, medication, or surgery.
Here are some references that I consulted while writing this article:
- Greenberg MS. Handbook of Neurosurgery. 9th ed. Thieme; 2019.
- Malik AA, Khan NA. Peroneal Nerve: Clinical Anatomy, Pathophysiology, and Management. Handbook of Clinical Neurology. 2015;130:305-20.
- Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. 8th ed. Wolters Kluwer; 2018.
- Rice D, McNair PJ, Lewis GN, Dalbeth N. Peroneal motor nerve conduction and strength in runners with unilateral plantar heel pain. J Orthop Sports Phys Ther. 2013;43(12):905-10.
- Spencer PS, Schaumburg HH. Experimental and Clinical Neurotoxicology. 2nd ed. Oxford University Press; 2000.