Planes of motion in the foot Pronation and supination are a combination of the motion of the three main joints of the foot Pronation Supination Ankle joint dorsiflexion plantar flexion Subtalar joint eversion inversion Transverse tarsal joint abduction adduction Anterior tibial muscle / tendon Origin Gerdy's tubercle Innervation DPN (L3-4) Function ankle dorsiflexion Clinical conditions Anterior tibialis rupture presents as sudden onset of dorsiflexion weakness in the active elderly patient Mononeuralgia diabetica foot drop in diabetics Posterior tibial muscle / tendon Insertion inserts on or has confluence with ligamentous structures with every tarsal and metatarsal bone except 1st metatarsal Innervation L4-5 Function supinates and inverts the hindfoot Injury will lead to inability to initiate heel rise from stance position Physical exam when checking muscle strength of the tibialis posterior muscle, keep the foot everted and plantar flexed to negate recruitment of the anterior tibial muscle with inversion Flexor hallucis longus tendon / muscle Anatomy lies deep and dorsal to FDL tendon at Henry's knot Vulnerable At risk during at posteromedial corner of subtalar joint during arthrodesis Valuable for augmentation in chronic insertional Achilles tendonitis close to distal Achilles tendon can be harvested as vascularized substitute Abductor Hallucis Function primary antagonist to adductor hallucis innervation comes from proximal 3rd of muscles allows you to be aggressive with mobilization and plantarward retraction which is required in adequate release of PTN in distal tarsal tunnel release Baxter's nerve release (must incise deep fascia) decompressing deep plantar space in compartment syndrome exposing Henry's knot for flexor transfer in PTTI