The fibularis tertius
Fibularis tertius · musculus fibularis tertius
A small muscle on the front of the ankle found in humans but rarely in apes.
What it does
The fibularis tertius is a small slip of muscle at the lower end of the long toe extensor, attaching to the fifth metatarsal. It lifts the outer edge of the foot and helps it clear the ground during walking.
Surprising fact
It is found in most humans but is rare in other apes, so it is thought to be linked to walking upright, although some people lack it.
Why it matters
It is a small example of how evolution has tuned the human foot and leg for walking on two feet.
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.