ANATOMY FOE, NUESES. 



[CHAP. I. 



while the limbs are solid, contain no viscera, and are merely 

 appendages of the trunk. The limbs or extremities, upper 

 and lower, are in pairs, and bear a rough resemblance to 

 one another, the shape of the bones, and the disposition of 

 the muscles in the thigh and arm, leg and forearm, ankle and 

 wrist, foot and hand, being very similar. 



The trunk and head contain two main cavities, and looking 

 at the body from the outside we should naturally imagine that 

 these two cavities were the cavity of the 

 head and the cavity of the trunk, respec- 

 tively. If, however, we divide the trunk 

 and head lengthwise into two halves, by 

 cutting them through the middle line 

 from before backwards, we find the trunk 

 and head are divided by the bones of the 

 spine into back and front cavities, and 

 not into upper and lower (vide diagram). 

 The dorsal or back cavity is a com- 

 a plete bony cavity, and is formed by the 

 vertebrae (bones of the spine) and by the 

 bones of the skull. It may be subdi- 

 vided into the spinal canal, containing 

 the spinal cord, and into the cranial cav- 

 ity, which is merely an enlargement of 

 the spinal canal, and contains the brain. 

 The ventral or front cavity is not a 



FIG. 1. DIAGRAMMATIC complete bony cavity, part of its walls 

 LONGITUDINAL SECTION OF being" formed of muscular and other tis- 



THE TRUNK AND HEAD. 1,1, 



the dorsal cavity; a, the sue ; it is much larger than the dorsal 



spinal portion; &, the era- cav i ty an( J may be subdivided into the 

 nial enlargement; c, c, the * * 



bodies of the vertebrae form- thoracic, abdominal, and pelvic cavities. 



ties ; 2, 2, the ventral cavity, trachea or windpipe, the lungs, gullet, 



subdivided into thoracic cav- , , . , . 



ity (d), abdominal cavity heart, and the great vessels springing 

 (e), and pelvic cavity (/) ; f rom an d entering into, the heart. The 



g, the nasal cavity; h, the . . 



mouth, or buccai cavity, abdominal cavity contains the stomach, 

 The alimentary canal (a*) is n gall-bladder, pancreas, spleen, kid- 



represented running through 



the whole length of the ven- neys, small and large intestines, etc. The 



pelvic cavity contains the bladder, rec- 



tum, and in the female, the generative organs. Connected with 



