The pectineus muscle is a flat, quadrangular muscle located in the upper inner thigh. It plays a key role in hip movement, primarily assisting with hip flexion and adduction. The muscle originates from the pectineal line of the pubis and inserts into the femur, making it an important muscle for activities like walking and running. This muscle is innervated by the femoral nerve and sometimes receives additional innervation from the obturator nerve. Due to its position, the pectineus muscle also contributes to stabilizing the pelvis during movement, helping maintain balance and proper posture.