THE ABDOMEN 86l 



lamina of the visceral pehdc fascia. In the female the anterior 

 relations are (i) the recto-uterine pouch of peritoneum, or pouch 

 of Douglas, with a few coils of small intestine, in front of which 

 are the posterior surface of the body of the uterus and the upper 

 part of the posterior wall of the vagina; and (2) the greater portion 

 of the posterior wall of the vagina. Posterior. — The lower three 

 sacral vertebrae, coccyx, levatores ani, and ano-coccygeal body. 

 Behind the rectum there is a large amount of areolar tissue. 

 Lateral. — The pelvic sympathetic plexuses, levatores ani, and 

 coccygei muscles, the lateral divisions of the superior hemorrhoidal 

 artery, and the corresponding veins. 



Anal Canal. — This is the terminal portion of the large intestine. 

 It extends from the lower end of the rectum, where that has 

 pierced the pelvic diaphragm at a point corresponding to the apex 

 of the prostate gland, to the anus, and it is the part which is sur- 

 rounded by the sphincter muscles. It is about i.\ inches in 

 length, and its lateral walls are in contact, so that in transverse 

 section it appears as an antero-posterior slit, in which respect it 

 differs from the rectum proper. Its direction is downwards and 

 backwards, and its antero-posterior measurement is from ^ to | inch. 



Relations — Anterior. — ^The bulb of the corpus spongiosum, the 

 base of the triangular ligament, and the membranous part of the 

 urethra. In the female the perineal body is anterior to it, and 

 separates it from the lower end of the vagina. Posterior. — ^The 

 ano-coccygeal body. Lateral. — ^The fat of the ischio-rectal fossae. 

 The anal canal is closely guarded by muscles in the follo\ving 

 manner, and to the following extent : the sphincter ani extemus 

 surrounds its termination in the anal aperture, the levatores ani 

 grasp it at its commencement, and the intervening part is sur- 

 rounded by the sphincter ani intemus. For the structure and 

 development of the rectmn and anal canal, see Index. 



Parts felt per Rectum in Catheterization. — A catheter having been passed 

 into the bladder, the following parts, in order from before backwards, may 

 be felt through the anterior wall of the bowel on the introduction of the 

 index finger : (i) the membranous portion of the urethra ; (2) the posterior or 

 rectal surface of the prostate gland ; and (3) the apical part of the external 

 trigone of the bladder, destitute of peritoneum, with a vas deferens on either 

 side, and very near each other — indeed, almost touching. During this 

 examination the finger may come in contact with the lower left, and perhaps 

 the right, valve of Houston. 



Middle Sacral Artery. — ^This vessel arises from the posterior aspect 

 of the abdominal aorta just above the bifurcation. Its course 

 is downwards in the middle line, behind the left common iliac vein 

 and the hypogastric sympathetic plexus, and it rests in succession 

 upon the following parts : the lower half of the body of the fourth 

 lumbar vertebra and the disc between it and the fifth, the body 

 of the fifth lumbar and the disc between it and the first sacral 

 vertebra, and the pelvic surfaces of the sacrum and coccyx. In the 

 pelvis it lies within the root of the pelvic meso-colon, being covered 

 by a portion of the pelvic colon, as low as the third sacral vertebra. 



