The plantaris
Plantaris · musculus plantaris
A tiny calf muscle with an extraordinarily long tendon, missing in some people.
What it does
The plantaris has a small muscle belly behind the knee and a very long, thin tendon that runs down between the calf muscles to the heel. It contributes little force to pointing the foot or bending the knee.
Surprising fact
The plantaris tendon is one of the longest in the body, and the muscle is absent in roughly one in ten people.
Why it matters
Surgeons can harvest its tendon for repairs elsewhere with little loss of function. A sudden "whack" in the calf during sport is sometimes blamed on it rupturing.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.