THE SKELETAL SYSTEM 



251 



teres ligament. Many muscles of the thigh and body wall are attached 

 to the coxal bone, which also serves to support the abdominal viscera. 

 The two coxal bones together with the sacrum and coccyx form the pelvis, 

 the shape of which differs somewhat in the two sexes. 



Femur. The femur or thighbone, which is the largest bone of the 

 body, has a shaft and two extremities. The upper extremity includes a 

 hemispherical head, a neck, and two trochanters, the greater and lesser. 

 The large gluteus muscle of the buttocks is inserted on the greater trochan- 

 ter while the psoas muscle is connected with the lesser trochanter. 

 Between the two extends the ridge of the intertrochanteric crest. 

 On the anterior side of the femur, the tendonous capsule of the hipjoint 

 is attached to the intertrochanteric line which separates neck and shaft. 



Jblood vessel 



^COMPACT BONE 



ARTICULAR LIGAMENT 

 Fig. 208. — Diagram of the structure of a long bone. (Redrawn after Kahn's "Das 

 Leben des Menschen," W. Keller & Co.) 



Among the remarkable adaptations manifested in the femur none is 

 more amazing than the arrangement of bony lamellae within the calcellous 

 bone of the upper extremity in such wise as to withstand the stresses and 

 strains of supporting the weight of the body with a maximum of strength 

 and minimum weight of material. The relations of the parts resemble 

 those of a Fairbairn's crane. In addition, the femurs together with the 

 coxal bone and sacrum form a natural arch of which the sacrum is the 

 keystone. 



The shaft of the femur is nearly cylindrical but on its dorsal side the 

 linea aspera extends as a ridge throughout its entire length. Several 

 muscles have their insertion along this line. The lower extremity of the 

 femur is distinguished by two articulating condyles, the median and the 

 lateral, separated by an intercondylar fossa. 



Patella. The knee-pan is a flattened bone which develops in the 

 tendon of the quadriceps femoris muscle at the lower extremity of the 

 femur. It has median and lateral facets, which articulate with corre- 

 sponding facets in the lower end of the femur. 



The Tibia. The tibia is considerably the larger of the two bones of 

 the shank. Its function is to transfer the weight of the body from the 



