THE SKELETAL SYSTEM 35 



The femur, or thigh bone, consists of a long tody 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 acetabu- 

 lum. 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 neok. Head and neck 

 together resemble a small 'Hoad stool,*' the neck corre- 

 sponding 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 tro- 

 chanters. 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 inter condyloid fossa, which is continued 

 on to the extensor surface of the bone as the grooved patel- 

 lar surface for articulation with the patella. The two 

 condyles articulate with the proximal end of the tibia. 



The tihia 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. Be- 

 yond the anchylosis it is cylindrical in cross section, but 



