THE HUMAN BODY 



Upon the ventral side of the head is the mouth-opening leading 

 into a tube, the alimentary canal, f (Fig. 2), which passes back 

 through the neck and trunk and opens 

 again on the outside at the posterior part 

 of the latter. In its passage through the 

 trunk-region this canal lies in the ventral 

 cavity. 



The Mammalia. In many vertebrate 

 animals the ventral cavity is not sub- 

 divided, but in the Mammalia it is; a 

 membranous transverse partition, the 

 diaphragm (Fig. 1, d), separating it into 

 an anterior chest or thoracic cavity, and 

 a posterior, or abdominal cavity. The 

 alimentary canal and whatever else passes 

 from one of these cavities to the other 

 must therefore perforate the diaphragm. 



FIG. 1. Diagram of the Body opened from the 

 front to show the contents of the ventral cavity. 

 d, diaphragm; h, heart; lu, lungs; st, stomach ; li, 

 liver- si, small intestines; c, large intestine. 



FIG. 2. Diagrammatic longi- 

 tudinal section of the Body, a, 

 the neural tube, with its upper 

 enlargement in the skull-cavity 

 at a'; N, the spinal cord; N' t 

 the brain; ee, vertebrae form- 

 ing the solid partition between 

 the dorsal and ventral cavi- 

 ties; b, the pleural,,and c, the 

 abdominal division of the ven- 

 tral cavity, separated from one 

 another by the diaphragm, d;i, 

 the nasal, and o, the mouth 

 chamber, opening behind into 

 the pharynx, from which one 

 tube leads to the lungs, I, and 

 another to the stomach, /; h, 

 the heart; k, a kidney; s, the 

 sympathetic nervous chain. 

 From the stomach, /, the in- 

 testinal tube leads through the 

 abdominal cavity to the pos- 

 terior opening of the alimen- 

 tary canal. 



