Innervation of flexor hallucis longus muscle: an anatomical study for selective neurotomy

Background: The aim of the study was to describe the innervation of flexor hallucis longus (FHL) and obtain its surgical coordinates to facilitate selective neurotomy. Materials and methods: Fifteen embalmed lower limbs of adults were studied. Anatomical dissections to isolate the innervating branches of FHL were performed. Distance between the supplying nerve of FHL, including both its origin and termination, and the medial malleolus were obtained, providing anatomical coordinates beneficial for surgery. Results: In all cases, FHL was innervated by only one branch, which originated from the tibial nerve. Mean distance between the medial malleolus and the nervous branch origin was 21.39 +/- 3.05 cm. Mean distance between the medial malleolus and the nervous branch termination was 12.7 +/- 1.59 cm. Length of the nervous branch innervating FHL was proportional to the length of the leg, measuring 8.69 +/- 2.45 cm. All nerves were located 15-17.4 cm above the medial malleolus. Conclusions: This anatomical study traced valuable surgical coordinates useful for performing selective peripheral neurotomy on the nerve branch innervating the FHL.