DIGESTIVE ORGANS. 



537 



Fig. 245. 



Lastly; there are a few muscles, which are concerned in the act of 

 expelling the faeces. These require a short notice. 1. The sphincter 

 ani, coccygeo-anal muscle, which keeps the anus constantly closed, ex- 

 cept during defecation. 2. The levator ani, subpubio-coccygeus, which, 

 with the next muscle, constitutes the floor of the pelvic and abdominal 

 cavities. It restores the anus to its place, when pushed outwards during 

 defecation. 3. The coccygeus, ischio-coccygeus, which assists the leva- 

 tor ani in supporting or raising the lower extremity of the rectum; and 

 4. The transversus perinei, ischio-perineal muscle, some fibres of which 

 unite both with the bulbo-cavernosi and with the sphincter ani muscles; 

 and, consequently, it is associated slightly with the action of both one 

 and the other. 



In regard to the intestinal canal, we find, that man holds a medium 

 place between the carnivorous and herbivorous animal, although approxi- 

 mating more to the latter. In 

 the carnivorous- for reasons 

 more than once mentioned it 

 is unnecessary that the food 

 should remain long; accord- 

 ingly, the canal is very short. 

 In the herbivora, on the other 

 hand, and for opposite reasons, 

 the canal is long, and there is 

 generally a large caecum and a 

 pouched colon. Cuvier 1 has 

 given tables of the length of 

 the digestive tube, compared 

 with that of the body; but 

 where the comparison has been 

 applied to man, the length of 

 the body has included that of 

 the legs. Instead, therefore, 

 of the canal, in him, being con- 

 sidered to bear the proportion 

 of six to one, it ought to be 

 doubled, or be regarded as 

 twelve to one; a proportion 

 somewhat greater than prevails 

 in the simise or ape tribe. It is 

 not, however, always in length, 



that the Canal of the herbivor- View of External Parietes of Abdomen, with the po- 

 OUS exceeds that of the Omni- sition of the Lines drawn to mark off its Regions. 



VOrOUS animal ; but aS a general * l - Line df awn from the highest point of one ilium 



- , ? ii to the same point of the opposite one. 2,2. Line drawn 



rule, It may DC amrmed, that itS from the anterior superior spinous process to the carti- 



capacity is much more consi- 



5. Ihe abdomen* in Which chondriac regions. 

 ,1 i v .. region 



the principal digestive Organs 



are situate, and whose parietes 



1 Leyons d'Anatomie Comparee, Paris, 1799. 



touching the most prominent part of the costal cartilages, 

 thus forming nine regions. 5, 5. Right and left hypo- 

 c regions. 6. Epigastric region. 7. Umbilical 

 8, 8. Right and left lumbar regions. 9. Hypo- 

 astric region. 10, 10. Right and left iliac regions. 11. 



part f the hypogastric ' sc 



