|The mucous sheaths of the tendons around the ankle. Medial aspect. (Plantaris labeled at bottom right.)|
|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)|
|Action:||Plantar flexes foot and flexes knee|
|Antagonist:||Tibialis anterior muscle|
It is innervated by the tibial nerve (S1, S2).
Origin and insertion
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.
Plantaris acts to weakly:
- 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." 
- Selim, Jocelyn (2004). "Useless Body Parts". Discover. 25 (6). Retrieved 2007-02-18.
- LUC plnt
- SUNY Labs 15:st-0412
- -1274675120 at GPnotebook
- plantaris+%28muscle%29 at eMedicine Dictionary