30 LABORATORY DIRECTIONS 



the point of union of the three component parts of the innominate. 

 (In kittens the sutures between them still exist, as well as a 

 small acetabular bone in the floor of the depression.) The parts 

 of the innominate are: (a) the ilium, extending anteriorly from 

 the acetabulum and connecting with the sacrum; (b) the ischium, 

 posterior to the acetabulum; and (3) the pubis, the ventral bar 

 of bone adjoining the pubic symphysis. 



The large opening between ischium and pubic is the obturator 

 foramen. It will be referred to frequently when the muscles of 

 the hind leg are studied. 



2. Femur. — This is the single bone of the thigh. It has a 

 large globular head which fits into the acetabulum. The large 

 roughened projection lateral to the head is the great trochanter 

 which serves for the attachment of many muscles. The lesser 

 trochanter is a small tubercle on the posterior side, a short dis- 

 tance below the head. The large depression on the posterior 

 side between the head and great trochanter is the trochanteric 

 fossa. The prominences on the distal end of the femur are the 

 lateral and medial condyles, and the groove between the condyles 

 is the intercondyloid fossa. 



3. Patella. — This is the knee cap. It is a sesamoid bone; 

 that is, it is formed by ossification of part of a tendon. There 

 are other sesamoid bones in the skeleton, but this is the largest. 



4. Tibia. — This is the larger of the two bones of the shank 

 and is the longest bone of the body. It articulates with the two 

 condyles of the femur by means of the lateral and medial tuber- 

 osities. Anteriorly the tibia has a prominent crest which dis- 

 appears distally. The projection on the distal end of the tibia 

 is the medial malleolus. 



5. Fibula. — ^The fibula is the slender bone of the shank. 

 It articulates with the tibia at both ends and with the ankle 

 distally. The expanded proximal end is the head; the promi- 

 nence at the distal end is the lateral malleolus. 



6. Tarsus. — The tarsus is composed of the seven bones in the 

 ankle. The calcaneus (sometimes calcaneum) is the largest of 

 the ankle bones and forms the heel. The astragalus forms the 

 chief articulation between the foot and the tibia. The navicular 

 or scaphoid is distal to the astragalus and is usually described as 

 boat-shaped. The four bones in the distal row, beginning 



