Anatomical variation of the semitendinosus muscle origin

Introduction The hamstring muscles are frequently implicated in posterior thigh pain due to strains. The hamstring muscles are the three most superficial muscles that span the posterior thigh, and consist of the biceps femoris, semitendinosus, and semimembranosus. The long head of biceps femoris originates from the inferiomedial aspect of the ischial tuberosity and inserts into the head of the fibula. The short head of biceps femoris originates from the linea aspera in the middle third of the femur, and combines with the long head to insert into the head of the fibula. The semimembranosus originates from the superolateral aspect of the ischial tuberosity and inserts into medial tibial condyle, popliteus fascia, and oblique popliteal ligament. The semitendinosus (ST) shares a common origin with the long head of biceps femoris from the inferomedial aspect of the ischial tuberosity and inserts medial to the tibial tuberosity as part of the pes anserinus, together with gracilis and sartorius tendons [1].