Supernumerary semitendinosus muscle: A rare case presentation and its clinical significance

[Extract]
During routine dissection in the anatomy lab, of a 79-year-old Caucasian ethnic-group male cadaver, an aberrant muscle was noticed among the hamstring muscles of the left limb (Fig. 1). This muscle took its origin from the lateral ridge of linea aspera and was located between the tendinous attachments of the short head of biceps femoris and adductor magnus muscle. The muscle had a cord-like appearance, with a total length of 34 cm and a diameter of 2.3 cm. As this muscle coursed distally, it was covered by the long head of biceps femoris muscle and the already bifurcated sciatic nerve. At its distal part, the muscle had an oblique course running from lateral to medial, whereas at the popliteal fossa it was superficial to the popliteal artery and vein, adjacent to the upper corner of the popliteal fossa. The tendon of the muscle was inserted to the medial tibial condyle, medial to the tendon attachment of the semimembranosus muscle. The remaining hamstring muscles, thus the short and long head of the biceps femoris originated typically from the linea aspera and the ischial tuberosity, respectively, and inserted with common tendon to the lateral aspect of the head of fibula, whereas the semitendinosus muscle commenced from the ischial tuberosity and attached to the medial surface of tibia.