The flexor hallucis has a medial and a lateral head inserted laterally to the abductor hallucis.
It is at first situated above the abductor hallucis, and then between it and the flexor digitorum brevis, both of which it supplies.
Adductor hallucis acts as a tensor of the plantar arches and also adducts the big toe and then might plantar flex the proximal phalanx.
Below the soleus muscle the nerve lies close to the tibia and supplies the tibialis posterior, the flexor digitorum longus and the flexor hallucis longus.
Some sources also state that the triceps surae and extensor hallucis longus invert.
In other words, the flexor hallucis longus arises laterally, while the flexor digitorum longus arises medially.
The form "hallux" (genitive, "hallucis") currently in use is however a blend word of the aforementioned forms.
Medially to adductor hallucis are the two heads of flexor hallucis brevis, below the tendon of flexor hallucis longus.
