8 4 



LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



ilium 



pubis 



posterior ends of the two ischia form prominent projections in the rabbit or a 

 curved rough surface in the cat, called the ischial tuberosity, and extend toward 

 the median line as the rami (singular, ramus) of the ischium, meeting in the 

 median ventral line to form the ischial symphysis. The anterior ventral part 

 of each innominate bone is formed by the pubis. Each pubis sends a projection, 

 the ramus, toward the median ventral line, the two rami uniting as the pubic 

 symphysis. Both ischial and pubic symphyses are in life composed of cartilage. 

 Between the rami of the ischium and pubis is the large obturator foramen. Ilium, 



ischium, and pubis meet at the acetabulum 

 and take part in the formation of its walls. 

 Draw the pelvic girdle from in front. 

 On a demonstration specimen of half of 

 the girdle of a kitten note complete separa- 

 tion and boundaries of ilium, ischium, and 

 pubis. Note further the presence in the 

 acetabulum of a small bone, the acetabular 

 bone, which forms that part of the acetabu- 

 lum which would otherwise be occupied by 

 the pubis. In the young of all mammals 

 the three bones of the pelvic girdle are sepa- 

 rate, as in the adults of reptiles (Fig. 25). 



The hind limb is fairly typical. The 

 femur has a head, a greater trochanter 

 lateral to the head (which in the rabbit 

 continues posteriorly terminating in a small 

 projection, the third trochanter), and a 

 lesser trochanter, situated below the head. 

 These trochanters serve for muscle attach- 

 ments. The large articulating surfaces at 

 the distal end of the femur are condyles (medial and lateral), and they bear 

 additional elevations or roughened areas, the epicondyles. At the knee joint 

 a patella is present. The shank is composed of a stout tibia and slender fibula, 

 the latter in the rabbit fused with the tibia for the greater part of its length. 

 The anterior face of the tibia presents a crest; its proximal articulating surfaces 

 are known as condyles; its distal ones as malleoli. The bones of the ankle are 

 identical with those of the human ankle and are designated by the same names, 

 which are, unfortunately, somewhat fanciful and not based upon comparative 

 anatomy. The name derived from comparative anatomy is given in paren- 

 thesis after the name derived from human anatomy. The ankle consists of seven 

 bones (cat), or six (rabbit). The largest and most conspicuous of these, which 

 projects backward as the heel, is the calcaneus (fibulare) . Articulating with the 

 malleoli of the tibia and fibula is the astragalus or talus (tibiale). Directly in 



acetabulum 



ischium 



FIG. 25. Half of the human pelvic 

 girdle at birth, showing the three bones of 

 which it is composed. Stippled regions 

 represent cartilage which later ossifies, 

 obliterating the boundaries between the 

 bones. (From a specimen loaned by the 

 anatomy department.) 



