LECTURE IV. 

 POSTERIOR LIMB. 



This limb also contains 20 bones, and is divided for study 

 into pelvis, thigh, leg, and foot. 



The pelvis is divided into two halves, each half being com- 

 posed of three bones closely united. These bones are distinct 

 in early life, but become united as the animal grows older. The 

 two halves of the pelvis bound the pelvic cavity which contains 

 the rectum, bladder, and sexual organs. Each half of the pelvis 

 articulates with the sacrum. 



The thigh contains one bone, the femur, which articulates 

 above with the pelvis and below with the larger of the two leg 

 bones. The femur belongs to the group which we have classified 

 as long bones and is the heaviest and strongest bone in the body. 

 This bone offers for study a shaft, upper and lower extremities. 

 The shaft shows three faces : external, internal, and anterior, which 

 are smooth and convex, and a posterior face which is rough and 

 irregular on the surface. There is a large projection on the 

 upper portion of the posterior face called the internal trochanter. 

 On the upper extremity we find a smooth rounded head which 

 articulates with a deep cavity in the pelvic bone above. On the 

 external surface and projecting above the head is the external 

 or great trochanter. The inferior .extremity is somewhat flat 

 from side to side and shows two rounded surfaces which we will 

 call condyles. These are separated by a deep groove known as 

 the trochlea. 



The leg contains three bones: tibia, fibula, and patella. 



The tibia is a long bone with a somewhat triangular shaft, 

 larger at the upper than at the lower end. It articulates above 

 with the femur, patella and fibula, and below with the bones of 

 the hock; i. e., the tarsal bones. This bone, like the femur, offers 

 for study a distinct shaft, upper and lower extremities. 



The shaft of the tibia presents three surfaces: the external, 



