An Anomalous Muscular Bundle Connecting Biceps Femoris to Semitendinosus

The hamstring muscle group consists of three muscles in the posterior thigh; the semitendinosus (ST) and the semimembranosus (SM) are located at the medial side, the biceps femoris at the lateral side (BF) [1]. The biceps femoris has two heads, which are anatomically and functionally distinct; the short (BFsh) and the long (BFlh) head. The semitendinosus and long head of the biceps femoris have a common origin from medial facet of ischial tuberosity, whereas the semimembranosus has origin from lateral facet of ischial tuberosity separately [2]. Short head of biceps femoris originates from the linera aspera to join the long head of biceps femoris. The semimembranosus muscle attaches to posteromedial aspect of the tibia while the semitendinosus muscle attach to anteromedial aspect of the tibia by way of a common tendon with gracilis and sartorius muscles. Biceps femoris muscle inserts laterally on the head of the fibula. With the exception of the BFSH, hamstrings are innervated by the tibial part of sciatic nerve. The sciatic nerve passes the proximal hamstring muscle complex on the lateral side at a distance of approximately 1 cm from most lateral aspect [3].