40 OBSTETRICAL AXATOMY. 



posing this band, is a thin muscle similar to the cremaster of the male 

 before the descent of the testicle into the scrotum ; this band is the 

 analogue of the round ligament in woman. The uterus is also main- 

 tained in position by the vagina posteriorly, and by the peritoneum, 

 which at this part forms four bands — the recto-uterine and vesico- 

 uterine. 



The interior of the uterus is divided into three compartments, cor- 

 responding to its divisions into body and cornua. The cavity of the 

 body communicates with the vagina by a narrow canal which traverses 

 the constriction or cervix of the uterus, and is designated the canal of 

 the cervix. In all the domesticated animals, except the Rabbit, this 

 canal is prolonged into the anterior extremity of the vaginal cavity like 

 the end of a tap into a barrel ; forming a very marked protrusion — the 

 cervix. In this is the opening {orificiuyn uteri externum) leading from 

 the vagina to the body of the uterus — the os titeri or os tincce ; around 

 this aperture the utero-vaginal lining membrane is curiously arranged 

 in transverse rugae disposed in a circular manner, and which gives to 

 this prominent part the appeai'ance of a radiating flower. In woman 

 the rugae of the canal are differently disposed, and resemble the branches 

 from the stem of a tree ; consequently, they have been named the 

 arbor vitce uterina or imhna plicata. 



The uterus is composed of three membranes — an external, or serous ; 

 Q, middle, ox nvuscular ; and an internal, or mucous tunic. The serous 

 or peritoneal membrane envelops all the organ, and is in reality only 

 an expansion of the broad ligaments, which are prolonged backwards 

 on the posterior extremity of the vagina, which they encircle and then 

 pass to the rectum and bladder, as well as to the lateral parietes of the 

 pelvis, constituting the four ligaments already referred to. Between 

 the two cornua this membrane forms a peculiar fraenum, which is very 

 developed in Solipeds. Owing to this arrangement, the cervix does not 

 receive any peritoneal covering. The muscular layer is composed of 

 longitudinal and circular fibres, analogous to those of the small in- 

 testines. At the insertions of the broad ligaments into the uterus, a 

 series of fasciculi are given off from this layer, which pass up between 

 the folds composing them, and have been found throughout their 

 extent, especially towards the ovaries. The fibres composing this coat 

 belong to the class of non-striated or involuntary muscles, being made 

 up of fusiform nucleated fibres lodged in a matrix of exceedingly 

 coherent granular matter. The appearance of this coat is different to 

 that of ordinary muscle, being much more dense and of a faint yellowish- 

 red hue, like the middle coat of arteries or the small intestines. The 

 superficial set of fibres are irregularly longitudinal in their direction, 

 and frequently interlace with each other ; the deep set are circular, 

 especially around the orifice of each oviduct and the os uteri, w^here 

 they are thick and close ; though even among these fibres irregular 

 fasciculi pass in different directions. Both layers are thicker in the 

 cornua than the body ; their obvious function is to diminish the volume 

 of the uterus during parturition. 



At an early period of life these fibres are perceptible, but during gesta- 

 tion they are greatly increased, and present a manifest striation. Their 

 increase is doubtless to permit the necessary dilatation of the uterus, 

 without allowing its parietes to become too attenuated and feeble ; 

 though to some extent they do diminish in thickness, according to the 

 species. The inner set are loosely adherent to the lining or mucous 



