THE FEMALE PELVIS 389 



canal. Around the cervix there is a shallow groove,, termed 

 ihefornix, which is deepest posteriorly. 



Anteriorly, the lower part of the vagina is related to the 

 urethra. This area may undergo sloughing from continual 

 pressure during parturition, and a urethro-vaginal fistula may 

 result. Above this level, the vagina is related to the posterior 

 surface of the bladder, from which it is only separated by some 

 loose cellular tissue, as it lies entirely below the peritoneum 

 of the utero - vesical fossa. This arrangement is of great 

 importance to the surgeon, as it permits the bladder to be easily 

 separated from the cervix and vagina. It is through this area, 

 too, that malignant diseases of the cervix may spread to the 

 bladder. 



Posteriorly, the vagina is related to the anal canal and rectum. 

 In its lower part it is separated from the anal canal by a fibro- 

 muscular mass which is termed the perineal body, and in its 

 upper fifth or more it is separated from the rectum by the lowest 

 part of the recto-uterine fossa and the viscera which it contains. 



During parturition the posterior commissure (p. 397) may 

 give way, and the laceration may involve the skin and superficial 

 tissues of the perineum as far back as the anus. The posterior 

 wall of the vagina may also be involved, and occasionally the 

 levator ani, and the sphincter muscles of the anal canal are 

 affected. Incontinence of faeces only occurs when the internal 

 sphincter is torn through. 



Following severe lacerations of the perineum which involve 

 the levator ani, the posterior vaginal wall may become prolapsed 

 through the vulva. This condition is usually accompanied 

 by a dilatation of the ampulla of the rectum, which pouches 

 forwards into the relaxed posterior vaginal wall, constituting 

 the condition known as a rectocele. A strain is thus placed on 

 the anterior wall of the vagina, and it in turn becomes prolapsed, 

 dragging the bladder with it to form a cystocele. Lastly, the 

 uterus itself descends, and a complete prolapse is the final stage. 



In the operation of colporrhaphy, which is undertaken as a 

 remedial measure, oval areas of mucous membrane are removed 

 in the long axis of the anterior and posterior vaginal walls, 

 and the cut edges are then stitched together, thus narrowing 

 the vagina. In removing the mucous membrane of the anterior 

 vaginal wall and in stitching the cut edges together subse- 

 quently, great care must be taken to avoid injuring the 

 bladder and urethra. 



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