Page:Laboratory Manual of the Anatomy of the Rat (Hunt 1924).djvu/49

Rh The femur, or thigh bone, consists of a long body with processes at each end for attachment of muscles, or for articulation with other bones. The proximal end is Y-shaped. The medial branch of the Y is capped with a hemispherical knob, the head, which fits into the acetabulum. The head is held in place by the round ligament (ligamentum teres femoris) of the femur, attached to the center of the articular surface. The head is joined to the shaft by the narrow cylindrical neck. Head and neck together resemble a small "toad stool," the neck corresponding to the stalk of the ""stool." The massive lateral branch of the Y, the great trochanter, is continued as a high thin ridge down the lateral surface of the femur. This ridge is sometimes referred to as the third trochanter, and the lateral branch of the Y as the first trochanter, the two being considered components of the greater trochanter. The lesser or second trochanter is a knob ventral to the base of the neck on the flexor surface of the femur. The intertrochanteric crest connects the greater and lesser trochanters. The trochanteric fossa is a deep depression at the base of the medial side of the greater trochanter. The lateral and medial condyles are large ventral swellings at the distal end of the femur. They are separated from each other by the deep intercondyloid fossa, which is continued on to the extensor surface of the bone as the grooved patellar surface for articulation with the patella. The two condyles articulate with the proximal end of the tibia.

The tibia extends from the knee to the ankle. The fibula is a slender bone posterior to the tibia. The two are anchylosed in the lower third of the tibia. These two bones resemble an archer 's bow, the fibula representing the cord, the forward bending tibia the wooden bow. The shaft or body of the tibia decreases in thickness distally. Beyond the anchylosis it is cylindrical in cross section, but