Muscles of the Hip and Lower Limb

The muscles of the hip and lower limb are listed in Table 7.5 and shown in Figures 7.17 to 7.20. These muscles, particularly those of the hips and thigh, tend to be large and heavy because they are used to move the entire weight of the body and to resist the force of gravity. Therefore, they are important for movement and balance.

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. 7.17 and Fig. 7.18). Before studying the action of these muscles, review the movement of the hip joint when the thigh flexes, extends, abducts, and adducts. Iliopsoas (includes psoas major and iliacus) originates at the ilium and the bodies of the lumbar vertebrae, and inserts on the femur anteriorly (Fig. 7.17). 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. We will consider only the gluteus maximus and the gluteus medius, both of which are illustrated in Figure 7.18.

Figure 7.17 Muscles of the anterior right hip and thigh.

     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 (Fig. 7.18). 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 (Fig. 7.17).

     All of these muscles originate from the pubis and ischium, and insert on the femur; the deep adductor magnus is shown in Figure 7.17. Adductor muscles adduct the thigh-that is, they lower the thigh sideways from a horizontal position. Because they press the thighs inward, these are the muscles that keep a rider on a horse. Notice that the gluts and the adductor group are antagonistic muscles.

Muscles That Move the Leg
The muscles that move the leg originate from the pelvic girdle or femur and insert on the tibia. They are listed in Table 7.5 and illustrated in Figures 7.17 and 7.18. Before studying these muscles, review the movement of the knee when the leg extends and when it flexes.
     Quadriceps femoris group (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), also known as the “quads,” is found on the anterior and medial thigh. The rectus femoris, which originates from the ilium, is external to the vastus intermedius, and therefore the vastus intermedius is not shown in Figure 7.17. These muscles are the primary extensors of the leg, as when you kick a ball by straightening your knee.
     Sartorius is a long, straplike muscle that has its origin on the iliac spine and then goes across the anterior thigh to insert on the medial side of the knee (Fig. 7.17). Because this muscle crosses both the hip and knee joint, it acts on the thigh in addition to the leg. The insertion of the sartorius is such that it flexes both the leg and the thigh. It also rotates the thigh laterally, enabling us to sit crosslegged, as tailors were accustomed to do in another era. Therefore, it is sometimes called the “tailor’s muscle,” and in fact, sartor means tailor in Latin.
     Hamstring group (biceps femoris, semimembranosus, semitendinosus) is located on the posterior thigh (Fig. 7.18). Notice that these muscles also cross the hip and knee joint because they have origins on the ischium and insert on the tibia. They flex and rotate the leg medially, but they also extend the thigh. Their strong tendons can be felt behind the knee. These same tendons are present in hogs and were used by butchers as strings to hang up hams for smoking-hence, the name. Notice that the quadriceps femoris group and the hamstring group are antagonistic muscles in that the quads extend the leg and the hamstrings flex the leg.

Muscles That Move the Ankle and Foot
Muscles that move the ankle and foot are shown in Figures 7.19 and 7.20.
     Gastrocnemius is a muscle of the posterior leg, where it forms a large part of the calf. It arises from the femur; distally, the muscle joins the strong calcaneal tendon, which attaches to the calcaneus bone (heel). The gastrocnemius is a powerful plantar flexor of the foot that aids in pushing the body forward during walking or running. It is sometimes called the “toe dancer’s muscle” because it allows a person to stand on tiptoe.
     Tibialis anterior is a long, spindle-shaped muscle of the anterior leg. It arises from the surface of the tibia and attaches to the bones of the ankle and foot. Contraction of this muscle causes dorsiflexion and inversion of the foot.

Figure 7.18 Muscles of the posterior right hip and thigh.

Peroneus muscles (peroneus longus, peroneus brevis) are found on the lateral side of the leg, connecting the fibula to the metatarsal bones of the foot. These muscles evert the foot and also help bring about plantar flexion. Flexor (not shown) and extensor digitorum longus muscles are found on the lateral and posterior portion of the leg. They arise mostly from the tibia and insert on the toes. They flex and extend the toes, respectively, and assist in other movements of the feet.

Figure 7.19 Muscles of the anterior right leg.

Figure 7.20 Muscles of the lateral right leg.