The plantaris has an extremely long thin tendon (up to 40 cm) relative to its small belly. It is absent in 7-10% of individuals. Historically described as a "leg lumbrical" for proprioception rather than motor function.
| Origin | Lateral supracondylar ridge of the femur — above the lateral head of gastrocnemius |
|---|---|
| Insertion | Posterior calcaneus — medial to the Achilles tendon |
| Nerve Supply | Tibial nerve (S1, S2) |
| Blood Supply | Sural arteries |
| Actions | Weakly plantarflexes the ankle; Weakly flexes the knee — negligible functional contribution; Provides proprioceptive feedback from the posterior knee |
|---|
Plantaris tendon rupture is a common mimicker of DVT and Achilles rupture — acute posteromedial calf pain from a partial plantaris tear was previously called "tennis leg" (now attributed to medial gastrocnemius tears). The plantaris tendon is harvested for tendon grafts and for vocal cord medialization. MRI distinguishes plantaris from Achilles injury.
Not directly palpable. Its tendon is sometimes visible on MRI and ultrasound medial to the Achilles.
Acute plantaris musculotendinous tear producing posteromedial calf pain and swelling, distinguished from DVT by ultrasound and managed conservatively.
