20 



TEXT-BOOK OF PHYSIOLOGY. 



tremity it is enlarged and forms 



FIG i. DIAGRAMMATIC LONGITUD- 

 INAL 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, />'. The 

 abdominal and thoracic divisions 

 of the ventral cavity, separated 

 from each other by a trans- 

 verse muscular partition, the 

 diaphragm d. B. The brain. 

 Sp. C. The spinal cord. e. The 

 esophagus. S. The stomach, 

 from which continues the intes- 

 tine to the opening at the poste- 

 rior portion of the body. /. The 

 liver, p. The pancreas, k. The 

 kidney, o. The bladder. /'. The 

 lungs, h. The heart. 



the cavity of the skull. This cavity 

 is lined by a membranous canal, 

 the neural canal, in which are con- 

 tained the brain and the neural or 

 spinal cord. Through openings in 

 the sides of the dorsal cavity nerves 

 pass out which connect the brain 

 and spinal cord with all the struc- 

 tures of the body. 



The ventral cavity is confined 

 mainly to the trunk of the body. 

 Its walls are formed by muscles 

 and skin, strengthened in most 

 animals by bony arches, the ribs. 

 Within the ventral cavity is con- 

 tained a musculo-membranous tube 

 or canal known as the alimentary 

 or food canal, which begins at the 

 mouth on the ventral side of the 

 head, and, after passing through 

 the neck and trunk, terminates at 

 the posterior extremity of the trunk 

 at the anus. It may be divided 

 into mouth, pharynx, esophagus, 

 stomach, small and large intestines. 



In all mammals the ventral 

 cavity is divided by a musculo- 

 membranous partition into t\vo 

 smaller cavities, the thorax and 

 abdomen. The former contains the 

 lungs, heart and its great blood- 

 vessels, and the anterior part of 

 the alimentary canal, the gullet or 

 esophagus; the latter contains the 

 continuation of the alimentary 

 canal that is, the stomach and 

 intestines and the glands in con- 

 nection with it, the liver and pan- 

 creas. In the posterior portion of 

 the abdominal cavity are found the 

 kidneys, ureters, and bladder, and 

 in the female the organs of repro- 

 duction. The thoracic and ab- 

 dominal cavities are each lined by 

 a thin serous membrane, known, 



