The tibial nerve is a direct continuation of the largest nerve in the human body, the sciatic nerve. It controls movement and relays sensation for the lower leg and foot. This nerve transmits signals that allow for complex foot and toe movements while also providing feeling to a substantial area of the foot, which is key to mobility and sensation below the knee.
The Path of the Tibial Nerve
The tibial nerve begins in the posterior thigh, forming after the sciatic nerve divides, typically just above the knee joint. It descends into the popliteal fossa, the space located behind the knee. Here, it gives off initial branches that supply muscles in the superficial posterior compartment of the leg.
From the knee, the nerve passes deep to the arch of the soleus muscle to enter the calf, known as the deep posterior compartment of the leg. Throughout this section, it runs alongside the posterior tibial artery, situated close to the tibia bone. This deep location shields it from surface trauma but places it near muscles and bones that can cause compression.
The nerve follows the leg contour until it reaches the inner side of the ankle. Just before entering the foot, it passes through the tarsal tunnel, a narrow anatomical passageway located behind the medial malleolus. The tibial nerve terminates by splitting into its two major terminal branches: the medial and lateral plantar nerves. These final branches distribute throughout the sole of the foot.
Motor and Sensory Responsibilities
The tibial nerve provides motor control to all muscles in the posterior compartment of the leg and the majority of the intrinsic muscles within the foot. This motor supply is responsible for plantar flexion, the action of pointing the foot and toes downward, used when pushing off the ground during walking. It also controls the flexion of both the small and large toes.
The nerve’s sensory role involves relaying information about touch, temperature, and pain from specific areas of the skin. The main areas of sensation it serves are the entire sole of the foot and the skin covering the heel. These sensory fibers enable a person to feel the ground with the foot.
When the Tibial Nerve Causes Pain
The tibial nerve is susceptible to injury, with compression being a common source of dysfunction and pain. Tarsal Tunnel Syndrome (TTS) represents the most frequent pathology, occurring when the nerve is compressed as it travels through the narrow tarsal tunnel at the ankle. This compression can be caused by local swelling from an ankle injury, the presence of a bone spur, or conditions like flat feet or arthritis.
Symptoms of TTS often manifest as a burning sensation, tingling, or numbness felt primarily on the sole of the foot and sometimes radiates toward the heel and toes. This abnormal sensation tends to worsen with activity, such as prolonged standing or walking. If the compression is severe or long-standing, it can lead to weakness in the small muscles of the foot and cause changes in foot posture.
Beyond localized compression at the ankle, the tibial nerve can also be affected by direct trauma to the leg, such as a severe fracture around the knee or tibia. In these proximal injuries, the resulting swelling or direct impact can lead to a loss of function in all the muscles the nerve supplies below the injury site. Such damage significantly impairs the ability to push off the ground with the foot and may result in extensive sensory loss across the sole.