Tibial Nerve

The tibial nerve is the major nerve in the lower leg. It comes from as a continuation of the sciatic nerve, which itself comes from the spinal cord, through the buttock, and supplies the lower leg with much of its motor (movement) and sensory function. The sciatic nerve divides into the common peroneal nerve, before continuing as the tibial nerve as it crosses the back of the knee.

The common peroneal nerve supplies the sensation and movement on the outside and and the front of the leg, while the tibial nerve supplies the muscles in the back of the lower leg.

Role of the tibial nerve in movement

The tibial nerve supplies the gastrocnemius and the soleus muscles of the calf, and the flexor muscles of the foot. The motor component of the tibial nerve is to cause the foot and toes to flex down to the floor. The tibial gives off branches into a medial (inner) and lateral (outer) nerve which supplies the outer foot and the inner foot. The tibial nerve thus is the driving power of the lower leg, letting us walk, run and push off the ground. The other branch of the sciatic nerve – the common peroneal supplies the muscles at the front of the lower leg. It also supplies the muscles in the foot that make the toes curl upwards. These muscles are weaker, as they are only designed to lift the weight of the foot, not of the entire body.

Role of the tibial nerve in sensation

The tibial nerve has a very limited role in sensation via the sensory branch which is called the sural nerve. This communicates with the sensory branches of the pernoneal nerve and supplies a small region of skin on the outside of the calf. The peroneal nerve supplies the rest of the outside of the leg.

Injuries to the tibial nerve

The tibial nerve is well protected as it lies deep in the calf muscle. It is cushioned against any blunt trauma and since any fracture normally affects the fibula as opposed to the tibia, it is rarely transected. The tibial nerve can occasionally be damaged if a Bakers cyst compresses the nerve, or if surgery on a Bakers Cyst transects the nerve. Other damage to the nerve can be caused by general disease such as multiple sclerosis, vitamin B12 neuropathy or damage from alcohol abuse.

If the tibial nerve is damaged, then the calf muscles will waste, and the sufferer will have problems walking using that legs. If the peroneal nerve is still working, then the foot will be pulled up by the action of the anterior leg muscles. However, such an injury is rare and would be an exception as opposed to a rule.

Medical role of the tibial nerve

Since the sensory input of the tibial nerve is small, it is commonly used for nerve biopsies and nerve grafts. The sural nerve – the part of the tibial nerve that grants sensation only supplies a small area of feeling on the outside of the calf – since loss of this area of sensation would not cause a significant disability, if nerve tissue is required, this part of the tibial nerve is frequently removed.