INTESTINAL CANAL. 39 



passes obliquely downwards to the centre of the sacrum, 

 thence in front of the middle line of the sacrum, and of the 

 coccyx, to terminate at the point of the latter. It is not regu- 

 larly cylindrical, but, just above the anus, is dilated inttfxO. wide 

 pouch, flattened from before backwards by the pressure of the 

 bladder, and very distinguishable upon the introduction of the 

 finger, for it is but seldom in a contracted state. It, of course, 

 has a flexure by adapting itself to the concavity of the sacrum, 

 and is bounded in front by the bladder, the prostate gland and 

 the vesiculae seminales of the male, and by the vagina and the 

 uterus of the female. 



The peritoneum covers only the superior two-thirds of the 

 rectum, and attaches it by the short duplicature, called the me- 

 sorectum, to the front of the sacrum. A small pouch, passing 

 down between the vesicula3 seminales almost to the base of the 

 prostate, is formed, as mentioned previously, by the peritoneum 

 in its course from the rectum to the bladder. 



The muscular coat of the rectum has a thickness and redness 

 surpassing much that of any other intestine, and is divided very 

 clearly into two Iamina3, the external of which consists in lon- 

 gitudinal and the internal in circular fibres. The external forms 

 in itself a complete coat continuous with the longitudinal bands 

 of the colon, but is much increased by additional fibres. The 

 circular fibres also form a complete coat, and, just below the 

 pouch of the rectum, are multiplied so much for eight or ten 

 lines as to be a perfect internal sphincter muscle, bearing a 

 strong analogy with the pyloric muscle of the stomach.* At 

 the anus, an arrangement of the muscular coat prevails, which, 

 as far as I know, has not been heretofore attended to by anato- 

 mists. The longitudinal fibres, having got to the lower margin 

 of the internal sphincter, turn under this margin between it and 



* It has been recently asserted that there is also a sphincter muscle four inches 

 above the anus, half an inch wide in front, and one inch wide behind, from whence 

 according to Mr. Velpeau the fibres go in crossing one another to fix themselves 

 to the front of the sacrum. Mr. Lisfranc appears to have first announced it and 

 Mr. Nelaton to have described it. Malgaigne, Anat, Chirurg. vol. 2d, p. 343. Paris, 

 1838. I doubt very much the uniformity of the distinct existence of such a mus- 

 cle, not having been able to find it in the dissections which I have instituted for 

 the purpose, unless a portion of the ordinary circular fibres should have been se- 

 lected for that designation. 



