1390 CLINICAL AND TOPOGRAPHICAL ANATOMY 



paratively little haemorrhage. In the perineal operation the posterior surface of the gland is 

 exposed by cutting through the perineum between the bulb and external sphincter ani, and 

 dividing the attachment of the recto-urethral muscle to the uro-genital diaphragm and its in- 

 ferior fascia. This exposes the back of the recto-vesical septum (aponeurosis of Denonvilliers) 

 which is split at its base, opening up the recto-prostatic space of Proust. By a longitudinal 

 incision into the prostate on each side the adenomatous lateral lobes may be enucleated sepa- 

 rately, and it is claimed without injury to the m-ethra or ejaculatory ducts (Hugh Young).* 



The bladder lies above the pubic symphysis at birth and so is mainl}^ an 

 abdominal organ. The anterior surface, in contact with the abdominal wall, 

 has no peritoneal covering, but posteriorly the peritoneal reflection descends to 

 cover the posterior surface of the prostate, which is relatively lower than in the 

 adult. 



The adult bladder when empty forms a pyriform contracted organ behind the symphysis, 

 and bounding the retro-pubic space of Retzius posteriorly. Into this space urine is extrava- 

 sated in extra-peritoneal ruptiu-e of the bladder, and may mount up behind the abdominal wall 

 in the extra-peritoneal tissue. The space is closed below bj' the pubo-prostatic ligaments and 

 prostatic plexus of veins. In distention, the neck of the bladder and prostate being relatively 

 fixed and immovable, the free apex rises up into the abdomen. As it does so it raises the peri- 

 toneum off the abdominal wall, so that in moderate distention 5 cm. (2 in.) of abdominal wall 

 above the pubes are free of peritoneum, and the bladder may be tapped here safely. The upper 

 surface and a little of the posterior are covered by peritoneum, which is also related to the upper 

 halves of the vesicute seminales. Below the recto-vesical pouch the base of the bladder pre- 

 sents a small triangular area in contact with rectum, bounded by the peritoneal cul-de-sac above, 

 the converging deferential ducts on each side and the prostate below. Through this triangle 

 which is rather expanded in distention of the bladder, punctm-e per rectum was formerly prac- 

 tised. The iitfero-lotcral surfaces are slung up by the levator ani as by a hammock. The inte- 

 rior of the bladder can be examined by the cystoscope in the living patient. The mucous mem- 

 brane is loose and rugose in contraction, except over the trigone at the base, the angles of 

 which are formed by the ureteric orifices and the internal meatus. The mucosa here is firmly 

 adherent to the muscular coat and smooth. In hypertrophy of the bladder-muscle from ob- 

 struction, a fas!'iculated appearance of the mucosa is seen and possibly diverticula between 

 the bands of muscle. 



Rectum and anal canal. — The rectum proper extends from the end of the 

 pelvic colon, opposite the third sacral vertebra, to the upper end of the narrow 

 anal canal, which runs downward and backward almost at right angles to the 

 rectum and is 3-4 cm. in length. The commencement of the rectum lies 13-14 

 cm. (5-5^ in.) above the anus in the adult. This point is marked internally 

 by an infolding of the mucosa on the right and anterior wall and to some extent 

 of the circular muscle fibres, due to the angle at which the free pelvic colon turns 

 into the fixed rectum. This shelf of mucous membrane is known as the upper 

 transverse fold (first valve of Houston). 



Under normal conditions the rectum does not form a reservoir for fscal material, which 

 is stored in the lower end of the pelvic colon, above the upper transverse fold, leaving the 

 rectum empty except in defa'cation. The rectum proper is subdivided into two compartments 

 by the inferior transverse fold on the anterior wall (third or great valve of Houston), situated 

 8-9 cm. (3-31 in.) al)ove the anus at the level of the anterior cul-de-sac of the peritoneum, and 

 resulting from the adaptation of the rectum to tlie hollow of the sacrum. This can usually 

 be made out on digital examination. The other transverse folds are inconstant and only 

 present on great distention. 



The rectum and anal canal may be divided into three ri^gions: (1) peritoneal 

 from the third sacral vertebra to the lower transverse fold and anterior reflexion 

 (jf peritoneum onto l)ladder or vagina; (2) infraperitoneal (rectal ampulla) 

 behnv this and above the levator ani; (3) anal canal, below the level of the 

 levator ani, constriction by which marks it off from the amptilla and converts 

 it into ail antero-poslcfior sht. 



The mucous membrane of t lie rectum proper is redundant and mobile and of a bright pink 

 colour as seen by the sigmoiiloscopc. It is dotted over by rectal pits, visible to the naked eye, 

 containing lymphoid follicles, and by the smaller and more numerous Lieberkhiin's glands. 

 In the pciitorKsa! chamber the mucosa is traiisver.sely plicated. In the rectal ampulla it presents 

 iongit udinal folds in which lie iiranches of the superior lurmorrhoidal vessels. These longi- 

 tudinal folds, known as t Ik; rectal columns, converge into tlu^ anal canal, and end at the l(^vel 

 of the anal valves half way down the canal, each uniting two adjacent valves. The anal valves 

 probably represent the; original cloacal membrane, <lividing the proctoda-um (formed from the 

 ei)iblast) from the hypoblastic hindgut, and ])ersistence of this membrane gives one form of 

 iiiipcrforatc anus (Wood Joricsf). The tearing down of a valve by hard fa'ces may be a cause 

 of anal fissure, etc. (Hall). The mucous membrane of the anal canal is more firmly adherent 



* .Studi(;s on lIvj)ertro|)hv and Cancer of the Prostate. .1. II. II. R('i)orts, vol. 14, 1906. 

 tlirit. Med. Journal, Dec. 14, 1<)()4. ^ 



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