INFERIOR FACE OF THE BODY. 149 



B. The Abdomen. 



Situation ; Limits ; Anatomical Base. In external anatomy 

 this region corresponds to the inferior surface of the abdominal cavity. 



It is circumscribed in front by the xiphoid region; behind by the 

 sheath and the scrotum in the male, and in the female by the mammary 

 glands ; on each side by the ribs, the flank, and the groin. 



The structures which form its base are, proceeding from without to 

 within, the skin, the panniculus carnosus, the tunica abdominalis, the 

 abdominal muscles, and, finally, the peritoneum, the serous membrane 

 which covers the parietes of the abdominal cavity, and the contained 

 organs. 



Beauties and Defects. It is important to consider the region 

 of the abdomen, for by its volume and its weight it influences loco- 

 motion. By certain other characteristics it gives information as to the 

 qualities of the animal and its state of health or of disease. We shall 

 now discuss it as to the two following points, intimately associated with 

 each other : the volume and the form. 



Volume. In a state of health the abdomen is elastic and yields 

 to digital pressure. It augments in volume after a meal and diminishes 

 in a measure when digestion is completed. It should be proportional 

 to the size and the type of the horse. 



It varies according to the breed. Though larger in some and smaller 

 in other strains, it is not on this account disproportional, comparatively 

 speaking. In animals used for slow or rapid work, its vertical diameter, 

 measured from the middle of the back, is most generally equal to the 

 length of the head. It is always more voluminous in the light saddle- 

 horse, the product of a half-breed and a pure-blooded animal, or of the 

 latter stock alone, except during the period of training. 



It is, perhaps, most exact to consider, with M. Eug. Gayot, the 

 volume of the abdomen as beautiful whenever this region continues the 

 external form of the thorax, i.e., when the latter becomes insensibly 

 continuous with the arch described by the ribs and the flank. Its 

 inferior line, when viewed in profile, should describe a graceful curve 

 from the sternum to the inguinal region. In this case it can be pre- 

 sumed that digestion and assimilation are well performed, because the 

 amplitude of the abdominal cavity corresponds to the volume of the 

 enclosed viscera, which is in relation with their functional activity, 

 particularly when the diet consists of aliments of good quality. 



When the abdomen is defective through lack of volume, it indi- 

 cates an animal with impaired assimilation, whose digestive functions 



