Plantaris

Original Editor - Samuel Adedigba

Top Contributors - Samuel Adedigba, Kim Jackson and Eugenie Lamprecht

Description

The Plantaris muscle is a small muscle with a short belly and long slender tendon that is located at the posterior compartment of the leg and along with the Gastrocnemius and Soleus muscles, forms the Triceps Surae. The long, thin tendon of plantaris is humorously called the freshman's nerve, as it is often mistaken for a nerve by first-year medical students.

Anatomy

Origin

It originates from the lower part of the lateral supracondylar line of the femur and from the oblique popliteal ligament of the knee joint and the muscle belly crosses the popliteal fossa inferomedially. In the proximal third of the leg, the muscle belly is situated between the popliteus muscle anteriorly and the lateral head of the gastrocnemius muscle posteriorly. Its long slender tendon courses distally between the medial head of the gastrocnemius muscle and the soleus muscle in the middle third of the leg.

Insertion

The muscle inserts in association with the Achilles tendon on the calcaneus or independently on calcaneus.

Nerve

Neural innervation of the plantaris muscle is provided by the tibial nerve (S1, S2).

Function

In terms of function, the plantaris muscle acts with the gastrocnemius but is insignificant as either a flexor of the knee, or a plantar flexor of the ankle.