The deep peroneal nerve, also called the deep peroneal nerve, is the peripheral nerve in the lower leg. It is the terminal branch of the common peroneal nerve , which is a branch of the sciatic nerve . The deep peroneal nerve contains motor and sensory fibers.
All nerves, except the cranial ones , branch off from the spinal cord. The nerves that extend from the spine to the extremities are called peripheral nerves. As your peripheral nerves travel through your arms and legs, they send out branches that connect to various muscles and other tissues to provide motor function (movement), sensory function (sensation), or both.
The roots of the sciatic nerve exit the spinal cord between the vertebrae in the lumbar and sacral regions of the lower back. The roots then join together and become a single nerve that travels through the buttocks and down the back of the thigh.
When the sciatic nerve reaches the so-called popliteal fossa (colloquially known as the "knee fossa"), it distinguishes two main branches:
The tibial nerve continues down the back of the leg, while the common peroneal nerve runs down the outside of the knee to reach the front of the lower leg. Just below the knee, the common peroneal nerve divides into two terminal branches :
- Superficial peroneal nerve
- Deep peroneal nerve
The deep peroneal nerve sends motor branches to various muscles in the lower leg, including :
- Tibialis anterior muscle
- Extensor hallucis longus
- Long toe extender
- Third fibularis
It also sends a branch to the ankle and then deposits two branches to the foot:
- The lateral branch, which connects to the muscles of the extensor brevis brevis and the extensor brevis brevis.
- The medial branch, which is the cutaneous nerve.
The lateral and medial branches are the terminal branches of the deep peroneal nerve.
From where it originates between the greater peroneal muscle and the neck of the fibula (the bone on the outside of the tibia), the deep peroneal nerve travels to the anterior tibia and down the anterior tibial artery.
It then travels between the tibialis anterior muscle and the extensor digitorum longus, and then along the extensor digitorum longus, sending motor branches to connect with these muscles, as well as the tertiary peroneal muscle in the lower third of the foot. leg.
Continuing down, it crosses the ankle and splits into terminal branches along the top of the foot.
The upper part of the deep peroneal nerve provides motor function to the muscles, while the lower part provides motor and sensory function to parts of the foot .
By innervating the tibialis anterior muscle, the extensor digitorum longus, the extensor digitorum longus, and the third peroneal muscle, the deep peroneal nerve is responsible for pulling the foot back, a movement opposite to the movement of the fingers. This movement, called dorsiflexion, is important for walking. Dorsiflexion is necessary both when the heel hits the ground and when the leg moves forward .
Through a lateral branch, this nerve allows the muscles to extend the toes.
The medial branch of the deep peroneal branch is sensory: a very small point on the top of the foot. It transmits information about the temperature and sensation of the skin between the big toe and the second toe ( the terminal branch of the superficial peroneal nerve provides sensory information to the rest of the upper surface of the foot).
The underlying condition associated with the deep peroneal nerve is called foot drop. This condition is the most common mononeuropathy (nerve injury) in the legs.
Foot drop is a loss of dorsiflexion of the foot due to a pinched or pinched nerve. This can happen at any point along the path of the nerve down the calf or to the foot. The squeeze usually occurs from overuse of tight shoes, especially tight ski boots. It can also be due to tumors or other growths that put pressure on the nerve. Also, the nerve can be damaged during knee surgery.
Other conditions that can cause sagging feet include:
A fall in the foot can also be caused by problems unrelated to the deep peroneal nerve, including an overgrowth of bone in the spinal canal, a tumor, or cyst compressing a nerve along the common sciatic or peroneal nerve.
Lowering the foot keeps the toes pointed as you walk, which can make it difficult for them to lift off the ground when you swing your foot. The foot tends to click when it lands on the ground with each step, because you cannot control its movement when it comes down.
Doctors can determine the cause of foot drop through a variety of tests and scans, including:
- Computed tomography
- Magnetic resonance imaging (MRI)
- Electromyography (EMG): checks the electrical activity of the muscles.
- Nerve conduction tests, which measure how fast electrical signals travel along the nerves.
How to treat a flabby foot depends on the cause. In some cases, this may be incurable and the associated pain and disability will be permanent.
Treatment may include :