The pectineus muscle is a flat, quadrangular muscle, situated at the anterior part of the upper and medial (inner) aspect of the thigh. Origin: pectineal line of the pubis Insertion: pass downward, backward, and lateral, to be inserted into the pectineal line of the femur which leads from the lesser trochanter to the linea aspera. Relations: The pectineus is in relation by its anterior surface with the pubic portion of the fascia lata. By its posterior surface with the capsule of the hip joint,