Muscles That Move the Thigh
The muscles that move the thigh have at least one origin on the pelvic girdle and insert on the femur. Notice that the iliopsoas is an anterior muscle that moves the thigh, while the gluteal muscles (”gluts”) are posterior muscles that move the thigh. The adductor muscles are medial muscles (Fig. 1.19).
Iliopsoas (includes psoas major and iliacus) originates at the ilium and the bodies of the lumbar vertebrae, and inserts on the femur anteriorly. This muscle is the prime mover for flexing the thigh and also the trunk, as when we bow. As the major flexor of the thigh, the iliopsoas is important to the process of walking. It also helps prevent the trunk from falling backward when a person is standing erect. The gluteal muscles form the buttocks
Gluteus maximus is the largest muscle in the body and covers a large part of the buttock (gluteus means buttocks in Greek). It originates at the ilium and sacrum, and inserts on the femur. The gluteus maximus is a prime mover of thigh extension, as when a person is walking, climbing stairs, or jumping from a crouched position. Notice that the iliopsoas and the gluteus maximus are antagonistic muscles.
Gluteus medius lies partly behind the gluteus maximus. It runs between the ilium and the femur, and functions to abduct the thigh. The gluteus maximus assists the gluteus medius in this function. Therefore, they are synergistic muscles.
Adductor group muscles (pectineus, adductor longus, adductor magnus, gracilis) are located on the medial thigh. All of these muscles originate from the pubis and ischium, and insert on the femur; the deep adductor magnus. Adductor muscles adduct the thigh that is, they lower the thigh side ways from a horizontal position. Because they press the thighs inward, these are the muscles that keep a rider on a horse.
