Branching pattern of tibial nerve in the tarsal tunnel - a cadaveric study

Background and aims: Tibial nerve is the larger terminal branch of sciatic nerve, ends by dividing into medial and lateral plantar nerves beneath the flexor retinaculum [Tarsal tunnel]. The level of bifurcation of the tibial nerve is differently quoted in text books and articles. The aim of the present study is to localize the level of bifurcation of tibial nerve. Materials and methods: 50 lower limbs from 25 cadavers available in the Department of anatomy, M.S. Ramaiah medical college and Bangalore medical college were used for the study. A reference line of 1 cm width ‘Medio Malleolar Calcaneal axis’ [MMC axis] made with OHP sheet was placed from tip of the medial malleolus of tibia to the medial tubercle of calcaneus and used as grid to classify the level of bifurcation of tibial nerve into 3 types. Type I, II, III represented the bifurcation proximal to, deep to and distal to this axis respectively. Results: Tibial nerve bifurcation was found to be type I in 92%, type II in 6%, type III in 2% of specimens. Most of the cases [32.6%] bifurcated between 5.1 to 10 mm proximal to MMC axis. The median distance of medial plantar nerve from medial malleolus was 21.28mm on left side and 20.735mm on right side. The mean of lateral plantar nerve from medial tubercle of calcaneus was 29.61mm on left side, and 28.6mm on right side. Conclusion: Detailed anatomical knowledge of tibial nerve prevents the damage to tibial nerve during various surgical procedures like fixation of fractures with external nailing of tarsal bones, medial displacement osteotomies and in tarsal tunnel surgeries.