HUMAN PHYSIOLOGY. 



FIG. i. DIAGRAMMATIC LONGITUDINAL 

 SECTION OF THE BODY. 



V,V. Bodies of the vertebrae which divide 

 the body into the dorsal and ventral 

 cavities, a, a'. The dorsal cavity. C, p f . 

 The abdominal and thoracic divisions 

 of the ventral cavity, separated from 

 each other by a transverse muscular 

 partition, the diaphragm d. B. The 

 brain. Sp. C. The spinal cord. e. The 

 esophagus. S. The stomach, from 

 which continues the intestine to the 

 opening of the posterior portion of the 

 body. /. The liver, p. The pancreas. 

 k. The kidney, o. The bladder. /'. 

 The lungs, h. The heart. 



organization of all the higher 

 animals and the center around 

 which the rest of the body is 

 developed and arranged with a 

 certain degree of conformity. 

 In all vertebrate animals the 

 bodies of the segments of the 

 vertebral column form a par- 

 tition which serves to divide 

 the trunk of the body into two 

 cavities viz., the dorsal and 

 the ventral. 



The dorsal cavity is found 

 in the head. Its walls are 

 not only in the trunk, but also 

 formed partly by the arches 

 which arise from the posterior 

 or dorsal surface of the ver- 

 tebrae and partly by the bones 

 of the skull. If a longitudinal 

 section be made through the 

 center of the vertebral column, 

 and including the head, the dor- 

 sal cavity will be observed run- 

 ning through its entire extent. 

 (See Fig. i.) Though for the 

 most part it is quite narrow, at 

 the anterior extremity it is en- 

 larged and forms the cavity of 

 the skull. This cavity is lined 

 by a membranous canal, the 

 neural canal, in which is con- 

 tained the brain and the neural 

 or spinal cord. Through open- 

 ings in the sides of the dorsal 

 cavity nerves pass out which 

 connect the brain and spinal 

 cord with all the structures of 

 the body. 



