The anatomy of the motor branches of the sciatic nerve: an anatomical study with clinical implications.

Background: The sciatic nerve gave the motor branches supply to: biceps femoris long and short head, semitendinosus, semimembranosus and adductor magnus muscles. The anatomy of these motor branches is highly variable. The aim of this study was to estimate the anatomy and morphometry of hamstring muscles innervation.

Materials and methods: The motor branches of the sciatic nerve were dissected from both sides from 20 cadaveric specimens (9 left and 11 right) from the 11 cadavers (4 females and 7 males) at the Department of Anatomy, Jagiellonian University Medical College Cracow.

Results: The motor branches of the sciatic nerve length, distance from piriformis muscle and number of all branches that exist from tibial nerve and common fibular nerve were measured. In most cases common fibular nerve gave off one branch to the short head of biceps femoris, in most cases the proximal hamstring tendon was innervated only by the first trunk, the highest number of branches were innervating the semimembranosus and the long head of biceps femoris, the longest branches were coming to the semimembranosus and the shortest to the proximal hamstring tendon CONCLUSIONS: The present study shows that there are various innervation types of the posterior group of thigh muscles. Knowledge of possible innervation patterns could be of utmost value to operators performing surgeries on the posterior region of the thigh.