Muscle
Plantaris
Small calf muscle with a long, variable tendon
High-yield
Plantaris makes only a small contribution to knee flexion and ankle plantarflexion. Some people lack the muscle, and its thin tendon can resemble a nerve during dissection.
Overview
Plantaris has a short muscle belly near the back of the knee and a slender tendon descending between gastrocnemius and soleus. The tendon usually approaches the heel along the medial side of Achilles, with several insertion patterns.
Reference facts
- Origin
- Distal lateral supracondylar region of the femur, with possible posterior capsular attachments
- Insertion
- Variable attachment near the posterior calcaneus, separately from or blending with the Achilles tendon
- Action
- Provides weak assistance to knee flexion and ankle plantarflexion
- Innervation
- Tibial nerve branches, usually summarized as S1-S2
- Blood supply
- Small sural arterial branches
Clinical correlation
A plantaris tear can cause calf pain, but imaging studies show that other injuries often explain symptoms called tennis leg. Plantaris may also remain intact when the Achilles tendon is torn.
Frequently asked questions
What does the plantaris do?
The plantaris provides weak assistance to knee flexion and ankle plantarflexion.
What nerve innervates the plantaris?
The plantaris is innervated by the tibial nerve branches, usually summarized as S1-S2.
Where does the plantaris attach?
The plantaris originates from the distal lateral supracondylar region of the femur, with possible posterior capsular attachments and inserts on the variable attachment near the posterior calcaneus, separately from or blending with the Achilles tendon.
What is the blood supply of the plantaris?
The plantaris is supplied by the small sural arterial branches.