Size and Function of the Muscles.

Function and Location of the Muscles of the Thigh, Leg, and Foot.

There are certain muscles essential for the proper function of the thigh, which are not visible externally. The Psoas muscle, mainly internal, helps to lift the thigh (37). It is one of the two muscles that flex the thigh and extend into the abdomen, originating from the upper vertebrae of the lower back and attaching with a strong tendon to the small Trochanter (39). Its counterpart, the Iliacus muscle, also belongs to the iliac region. The second muscle, which flexes the thigh, can be partially seen in illustration A, near the Longus and Membranosus muscles, identified as 40 and 41. It fills the entire internal cavity of the hip bone (34), attaching to the small Trochanter (39) and is called the Iliacus. However, its small size makes it barely visible in the illustration.

40. Membranosus: This muscle, covered with a membrane, extends the entire length of the thigh to the foot and rotates the leg outward. It originates from the upper part of the ilium and sacrum and twists outward, planting itself along the entire outer edge of the shin (44) with a broad, fleshy tendon. See illustrations A, B.

41. Longus: Named for its length, this muscle pulls the leg inward towards the other leg. It originates from the upper and front parts of the hip or pelvic bone (34) and descends to within the inner protrusion of the shin bone (44), being the longest and thinnest muscle. See illustration A.