Flexor hallucis brevis

The flexor hallucis brevis (Latin: musculus flexor hallucis brevis) is a small deeply-located foot muscle. It is situated on the medial aspect of the foot within the plantar side. Therefore, it is also known as one of the muscles of the big toe and belongs to the medial plantar foot muscle group. The flexor hallucis brevis is composed of two bellies - lateral and medial, and it aids in flexion of the big toe.

Flexor hallucis brevis
Origin

Lateral belly - lateral cuneiform bone, cuboid bone

Medial belly - tendon of the tibialis posterior muscle

Insertion

Lateral belly - lateral aspect of base of proximal phalanx of hallux

Medial belly - medial aspect of base of proximal phalanx of hallux

ActionFlexion of hallux, supports medial longitudinal arch of foot
InnervationMedial plantar nerve (S1 - S2)
Blood supply Medial plantar and first plantar metatarsal arteries

Origin

The lateral belly of the flexor hallucis brevis muscle originates from the lateral cuneiform bone and cuboid, while the medial belly arises from the tendon of the tibialis posterior muscle.

Insertion

The lateral belly of the muscle inserts on the lateral aspect of the base of the proximal phalanx of the hallux, while the medial belly - on the medial aspect of the base of the proximal phalanx of the first toe.

Action

The flexor hallucis brevis muscle provides flexion of the hallux at the first metatarsophalangeal joint. Also, it supports the medial longitudinal arch of the foot.

Innervation

The flexor hallucis brevis is innervated by the medial plantar nerve (S1 - S2) - one of the terminal branches of the tibial nerve.

Blood supply

The flexor hallucis brevis muscle receives arterial blood supply from the first metatarsal and medial plantar arteries.