Muscle · Foot

Flexor hallucis brevis

Musculus flexor hallucis brevis

A muscle in the sole running along the underside of the big toe's metatarsal, arising from the bones and tendon-sheath at the middle of the foot and splitting into two heads that pass either side of the joint at the ball of the foot. Each head contains a sesamoid — a small free bone inside the tendon — and those two sesamoids are what the body actually stands on when weight goes through the ball of the big toe. That is the point of the muscle: it bends the big toe down at its knuckle, and in doing so it holds a pair of bearing surfaces under the joint that carries more load at push-off than any other point in the foot.