External plantar nerve

External Plantar Nerve

The external plantar nerve is a branch of the tibial nerve, which is one of the major nerves in the lower limb. It provides sensory innervation to the lateral and plantar aspects of the foot. In this article, we will explore the anatomy, function, and clinical significance of the external plantar nerve.

Anatomy

The external plantar nerve arises from the tibial nerve just below the medial malleolus, which is the bony prominence on the inner side of the ankle. It descends along the medial side of the foot, running deep to the abductor hallucis muscle. As it reaches the plantar aspect of the foot, it divides into two branches: the lateral plantar nerve and the medial plantar nerve.

The lateral plantar nerve continues along the lateral side of the foot, supplying sensory innervation to the fifth toe and the lateral half of the fourth toe. It also provides motor innervation to the muscles of the lateral compartment of the foot, including the abductor digiti minimi, flexor digiti minimi brevis, and quadratus plantae.

The medial plantar nerve travels along the medial side of the foot, supplying sensory innervation to the medial half of the fourth toe and the entire third toe. It also provides motor innervation to the muscles of the medial compartment of the foot, including the abductor hallucis, flexor digitorum brevis, and flexor hallucis brevis.

Function

The external plantar nerve plays a crucial role in the sensory and motor functions of the foot. Sensory innervation from the lateral plantar nerve allows for the perception of touch, pain, and temperature in the lateral and plantar aspects of the foot. Sensory innervation from the medial plantar nerve provides similar functions in the medial aspect of the foot.

Motor innervation from both branches of the external plantar nerve enables the muscles of the foot to perform various movements. The muscles in the lateral compartment of the foot, innervated by the lateral plantar nerve, contribute to the abduction and flexion of the fifth toe. The muscles in the medial compartment of the foot, innervated by the medial plantar nerve, contribute to the abduction and flexion of the big toe.

Clinical Significance

Injuries or compression of the external plantar nerve can lead to various clinical manifestations. Common conditions affecting this nerve include Morton's neuroma, tarsal tunnel syndrome, and plantar fasciitis.

Morton's neuroma is a painful condition characterized by the thickening of the tissue around the nerve, usually between the third and fourth toes. It can cause pain, tingling, and numbness in the affected area.

Tarsal tunnel syndrome occurs when the external plantar nerve is compressed as it passes through the tarsal tunnel, a narrow space on the inner side of the ankle. This compression can result in pain, burning sensation, and weakness in the foot.

Plantar fasciitis is a condition characterized by inflammation of the plantar fascia, a thick band of tissue that connects the heel bone to the toes. In some cases, the inflammation can irritate the external plantar nerve, leading to pain and discomfort in the foot.