Flexor Hallucis Brevis - Lateral Head
Foot
One of the two heads that helps push off through the big toe — the lateral sesamoid under the big toe joint sits within this tendon and distributes ground forces.
Function
Flexes great toe at MTP joint; supports medial longitudinal arch
Origin
Plantar surfaces of cuboid and lateral cuneiform; slip from tibialis posterior tendon
Insertion
Lateral side of base of proximal phalanx of great toe, via lateral sesamoid
Innervation
Medial plantar nerve, with variable contribution from lateral plantar nerve (S1-S3)