THE ABDOMEN AND ITS CONTENTS m 



drawn, to prevent loss of the injected mass. The walls of the 

 portal vein appear to become thinner as it nears the liver, 

 consequently it is most often ruptured near the liver when the 

 mass is injected under too much pressure. The hepatic portal 

 vein courses along the right side of the Spigelhan (caudate) 

 lobe of the liver dorsad of the hepatic artery (45) before entering 

 the liver at the transverse fissure. 



Diaphragm (Fig. 28) : Note the position, form relations, 

 structure and functions of this organ. Its tw^o crura straddle 

 the aorta and become tendonous before finally inserting dorsad of 

 the abdominal aorta near the origin of the fourth lumbar artery. 



D. THE DIGESTIVE SYSTEM 



The digestive system includes the digestive tract and the 

 digestive glands. 



Digestive Tract : The mouth is the cephalic portion of the 

 digestive tract and extends from the lips to the pharynx. 

 Method: Access to the oral cavity is gained by loosening one of 

 the mandibular rami, by disarticulating the symphysis mandib- 

 ulae and the articulation, or by cutting off the coronoid 

 process and through the symphysis (Fig. 3) . With the cartilage 

 knife loosen the lateroventral side of the oral wall from the 

 mandibular symphysis well into the esophagus; then evert 

 the floor of the mouth laterad, with the tongue attached to the 

 intact mandibular ramus. 



The teeth are of two kinds according to function: Cutters, 

 4 above and 2 below, and grinders, 12 above and 10 below, 

 making a total of twenty-eight. The location and numerical 

 distribution of these teeth, that is, the number of incisors, 

 canines, premolars, and molars are indicated by a dental 

 formula : 



Rabbit I. ^.C.^.PM.f^,M.ff 28 



I- 1 0-0 2-2 7,-2, 



Man I. — , C. — ' PM. ^, M. ^ 32 



2-2 i-i 2-2 2>-?> 



