Malformation of Rectum 



383 



A, depression for z 

 piece of rectum, R ; B, 

 bladder ; M, Meckel's 

 diverticulum ; CE, future 

 oesophagus ; P, pharynx ; 

 u, urachus. 



more stretched and thinned is its wall ; the surgeon must proceed, 

 therefore, with the utmost gentleness in using the enema or scoop 

 when endeavouring to empty it. The muscular coat being greatly 

 stretched and enfeebled, there is no chance of a natural evacuation 

 taking place. 



Development. The blind end of the large intestine descending 

 into the pelvis is separated by a thick septum 

 from the surface of the perineum. Then a de- 

 pression at the site of the future anus deepens 

 upwards to form a short, shut sac ; at last the 

 septum is absorbed, and the pelvic and anal 

 pieces of the rectum become continuous. Thus, 

 the pelvic portion of the rectum is developed from 

 the hypoblast, whilst the anal portion is the result 

 of an involution of the epiblast. 



Zmperforate rectum results from persist- 

 ence of the septum ; it may exist with a perfectly 

 formed anus. Should absorption of the septum 

 be incomplete, an annular constriction will be 

 detected an inch or so within the anus. 



The close association of the rectum and 

 urinary bladder during development suggests 

 how, from arrest of development, the bowel may 

 open into the vagina or urethra, or on to the perineum. 



In obstinate constipation in infants digital exploration of the 

 rectum must not be neglected, for, although the anus is well formed, 



the pelvic portion of the large 



intestine may not be deve- 

 loped, or may be represented 



only by a cord descending 



towards the perineum. 



Xmperforate anus. 



Though the pelvic and anal 



portions may be perfectly 



developed, the orifice may 



be occluded by a membrane 



which may be easily broken 



through. 



Relations. The upper 



part of the rectum rests upon 



the sacrum, the sacral plexus, 



and the pyriformis. Coils of small intestine dropping down into the 



recto-vesical pouch intervene between it and the distended bladder. 



The uterus and vagina would also be in front of it (v. p. 389). The 



ureters and various branches of the internal iliac artery lie against its 



side. (There is no definite limit between the first and second parts of 



c, rectum, opening into bladder, l> ; a. penis. 



