1046 THE ORGANS OF DIGESTION. 



The surgical anatomy of the rectum is of considerable importance. There may be congen- 

 ital malformation due to arrest or imperfect development. Thus, there may be no inflection of 

 the epiblast (see page 134), and consequently a complete absence of the anus; or the hind-gut 

 may be imperfectly developed, and there may be an absence of the rectum, though the anus is 

 developed ; or the inflection of the epiblast may not communicate with the termination of the 

 hind-gut from want of solution of continuity in ';he septum which in early foetal life exists 

 between the two. The mucous membrane is thick and but loosely connected to the muscular 

 coat beneath, and thus favors prolapse, especially in children. The vessels of the rectum are 

 arranged, as mentioned above, longitudinally, and are contained in the loose cellular tissue between 

 the mucous and muscular coats, and receive no support from surrounding tissues, and this favors 

 varicosity. Moreover, the blood from these vessels is returned into the general circulation 

 through two distinct channels part through the systemic system and part through the portal 

 system so that they may be said to be placed between the portal and systemic circulations, and 

 thus predisposed to congestion and consequent dilatation. In addition to this, there are no 

 valves in the superior hfemorrhoidal veins, and the vessels of the rectum are placed in a depend- 

 ent position, and are liable to be pressed upon and obstructed by hardened faeces. The anatom- 

 ical arrangement, therefore, of the haemorrhoidal vessels explains the great tendency to the 

 occurrence of piles. Again, the presence of the Sphincter ani is of surgical importance, since 

 it is the constant contraction of this muscle which prevents an ischiq-rectal abscess from healing 

 and causes it to become a fistula. Also, the reflex contraction of this muscle is the cause of the 

 severe pain complained of in fissure of the anus. The relations of the peritoneum to the rectum 

 are of importance in connection with the operation of removal of the lower end of the rectum 

 for malignant disease. This membrane gradually leaves the rectum as it descends into the 

 pelvis ; first leaving its posterior surface, then the sides, and then the anterior surface to become 

 reflected in the male on to the posterior wall of the bladder, forming the recto-vesical pouch, and 

 in the female on to the posterior wall of the vagina, forming Douglas's pouch. The recto-vesical 

 pouch of peritoneum extends to within three and a half or four inches from the anus, so that it 

 is not safe to remove more than three inches of the entire circumference of the bowel for fear 

 of the risk of opening the peritoneum. When, however, the disease is confined to the posterior 

 surface of the rectum, or extends farther in this direction, a greater amount of the posterior 

 wall of the gut may be removed, as the peritoneum does not extend on this surface to a lower 

 level than five inches from the margin of the anus. The recto-vaginal or Douglas's pouch in 

 the female extends somewhat lower than the recto-vesical pouch of the male, and therefore it is 

 necessary to remove a less length of the tube in this sex. 1 Upon introducing the finger into the 

 rectum the membranous portion of the urethra can be felt, if an instrument has been introduced 

 into the bladder, exactly in the middle line ; behind this the prostate gland can be recognized 

 by its shape and hardness and any enlargement detected ; behind the prostate the fluctuating 

 wall of the bladder when full can be felt, and if thought desirable it can be tapped in this situ- 

 ation ; on either side and behind the prostate the vesiculae seniinales can be readily felt, espe- 

 cially if enlarged by tubercular disease. Behind, the coccyx is to be felt, and on the mucous 

 membrane one or two of Houston's folds. The ischio-rectal fossae can be explored on either 

 side, with a view to ascertaining the presence of deep-seated collections of pus. Finally, it will 

 be noted that the finger is firmly gripped by the sphincter for about an inch up the bowel. 



By gradual dilatation of the sphincter the whole hand can be introduced into the rectum so 

 as to reach the descending colon. This method of exploration is rarely, however, required for 

 diagnostic purposes. 



The colon frequently requires opening in cases of intestinal obstruction, the descending colon 

 being usually the portion of bowel selected for this operation. The operation of colotomy may 

 be performed either without opening the peritoneum by an incision in the loin (lumbar colotomy), 

 or by an opening through the peritoneum (inguinal colotomy). Lumbar colotomy is performed 

 by placing the patient on the side opposite to the one to be operated on, with a firm pillow under 

 the loin. A line is then drawn from the anterior superior to the posterior superior spine of the 

 ilium, and the mid-point of this line (Heath) or half an inch behind the mid-point (Allingham) 

 is taken, and a line drawn vertically upward from it to the last rib. This line represents^ with 

 sufficient correctness, the position of the normal colon. An oblique incision four inches in length 

 is now made midway between the last rib and the crest of the ilium, so that its centre bisects 

 the vertical line, and the following parts successively divided: (1) The skin, superficial fascia, 

 with cutaneous vessels and nerves and deep fascia. (2) The posterior fibres of the External 

 oblique and anterior fibres of the Latissimus dorsi. (3) The Internal oblique. (4) The lumbar 

 fascia and the external border of the Quadratus luniborum. The edges of the wound are now 

 to be held apart with retractors, and the transversalis fascia will be exposed. This is to be 

 opened with care, commencing at the posterior angle of the incision. If the bowel is distended, 

 it will bulge into the wound, and no difficulty will be found in dealing with it. If, however, the 

 gut is empty, this bulging will not take place, and the colon will have to be sought for. The 

 guides to it are the lower end of the kidney, which will be plainly felt, and the outer edge of 

 the Quadratus lumborum. The bowel having been found, is to be drawn well up into the 

 wound, and it may be opened at once and the margins of the openings stitched to the skin at 

 the edge of the wound ; or, if the case is not an urgent one. it may be retained in this position 

 by two harelip pins passed through the muscular coat, the rest of the wound closed, and the 



1 Allingham says one inch less in the female. 



