Our Flexor Hallucis Longus Muscle Anatomy
This muscle is present on the backside of lower leg and is called FHL for short.
The name though large and sounds complicated but is self-explanatory. Flexor is a muscle that flexes or bends the body part, it is attached to; Hallucis refers to big toe and Longus defines its greater length compared to the other shorter flexor muscle of the big toe.
Flexor hallucis longus is present deep in the posterior compartment of the lower leg.It arises from the lower two third of the fibula, on its back. Fibula is the smaller of the two leg bones and is present on the outer side of the leg. A part of the muscle also arises from the connecting membrane present between tibia and fibula.
The muscle descends downwards and converts into a tendon (muscle to bone fibrous attachment). This tendon travels behind the inner bump of the ankle and goes under the foot. In the sole of the foot it runs, alongside the other flexor muscle of the big toe, the short one, called flexor hallucis brevis.
It finally inserts on the lower or under surface of the distal phalanx of the big toe. The big toe consists of two bones called phalanges. Distal phalanx is the one present towards the nail side of the toe.
Posterior tibial fibular vessels
Tibial nerve S2, S3
When flexor hallucis longus muscle contracts, its tendon pulls the lower surface of the big toe bone and therefore, bends the toe downwards.It also acts to bend the foot downwards (plantarflexion) and twist it inwards (inversion).
It helps to push off the surface during walking.Injuries of flexor hallucis longus tendon are quite common in ballet dancers a condition termed as Dancer’s tendonitis. The reason being the dancer’s continuous and repetitive downward bending of the toes.