Plantaris muscle

From Wikipedia, the free encyclopedia

Plantaris muscle

The mucous sheaths of the tendons around the ankle. Medial aspect. (Plantaris labeled at bottom right.)
Latin	musculus plantaris
Gray's	subject #129 483
Origin:	Lateral supracondylar ridge of femur above lateral head of gastrocnemius
Insertion:	Tendo calcaneus (medial side, deep to gastrocnemius tendon)
Artery:	sural arteries
Nerve:	tibial nerve
Action:	Plantar flexes foot and flexes knee
Antagonist:	Tibialis anterior muscle
Dorlands/Elsevier	m_22/12550213

Plantaris is a vestigial structure and one of the superficial muscles of the posterior crural compartment of the leg.

It is innervated by the tibial nerve (S1, S2).

1 Origin and insertion
2 Functions
3 Additional images
4 References
5 External links

[edit] Origin and insertion

It arises from the inferior part of the lateral supracondylar line of the femur at a position slightly superior to the origin of the lateral head of gastrocnemius.

Also, it may arise from the oblique popliteal ligament.

Passing inferomedially posterior to the knee joint, it becomes tendinous while passing distally to insert into the tendo calcaneus, or occasionally separately inserting into the medial side of the calcaneus.

[edit] Functions

Plantaris acts weakly to:

plantarflex the ankle joint
flex the knee joint

Plantaris may also provide proprioceptive feedback information to the central nervous system regarding the position of the foot. The unusually high density of proprioceptive receptor end organs supports this notion.

Its motor function is so minimal that its long tendon can readily be harvested for reconstruction elsewhere with little functional deficit. "Often mistaken for a nerve by freshman medical students, the muscle was useful to other primates for grasping with their feet. It has disappeared altogether in 9 percent of the population." ^[1]