BLADDER, NORMAL ANATOMY. 



377 



cretory tube, whereby this fluid is wholly 

 discharged from the system. 



A urinary bladder has not been ascertained 

 to exist in any of the invertebrate division of 

 animals, and in the vertebrate there is a great 

 diversity with respect to it : thus in the class 

 Pisces, this organ is absent in all the osseous 

 family, in most of whom, however, the two 

 ureters unite below, and form a slight heart- 

 shaped dilatation which opens externally be- 

 hind the anus in common with the sexual 

 organs : this vesicle, though somewhat analogous 

 to, cannot be considered as a perfect reservoir. 

 In most of the cartilaginous fishes it is absent 

 also, as in the ray and shark, in whom the 

 ureters open as in birds into a cloaca, or reser- 

 voir common to the renal, sexual, and intes- 

 tinal discharges; in some, however, of this 

 family it is present, as in the cyclopterus or 

 lump-fish, the lophius piscatorius, &c. ; in the 

 latter it is very capacious, and its coats are so 

 thin as to be transparent; it receives the ureters 

 anteriorly, and opens, as is usual in fish, behind 

 the anus, in common with the genital ducts. 



In Reptilia, the bladder is present in some, 

 as the Batrachia and Chelonia ; it is absent in all 

 the Ophidia, and in many of the Sauria, as 

 the crocodile, the gecko, and the lizard ; while 

 again it exists in many of the same division, as 

 the iguana, chameleon, draco, &c. In the 

 Batrachia, as the frog and the toad, it is situated 

 in front of the rectum or cloaca, into which 

 it opens ; the ureters open into the latter poste- 

 riorly, from whence the urine is directed into 

 the bladder by the muscular contraction of the 

 cloaca and of the sphincters of the anus. In 

 the frog its cavity is large, parietes thin, and 

 its fundus divided into two cornua. In the 

 Chelonia, as the tortoise, it is very large, and 

 the ureters open into the urethra anterior to its 

 cervix, the urine must therefore return or reas- 

 cend to enter the bladder. In the Ophidia or 

 the Serpent tribe, each ureter dilates inferiorly 

 into a small vesicle, which then opens into the 

 cloaca, and there is no other approximation to 

 a bladder; in such of the Sauria as this organ 

 exists, it opens into the cloaca. 



In Aves the bladder is always absent ; in 

 the whole of this extensive class, the ureters 

 open into the cloaca, and the urine, which is so 

 earthy as to appear almost solid, is there min- 

 gled with the faeces, in common with which it 

 is discharged at short and repeated intervals. 

 In the Ostrich and Cassowary the cloaca is 

 very dilatable, and its muscular structure is so 

 organized as to be enabled to retain within it, 

 and to discharge occasionally a considerable 

 quantity of urine; hence in these animals a 

 vesica urinaria has been by some erroneously 

 supposed to exist. 



In all mammalia this organ exists, and in 

 every member of this class the ureters enter it 

 obliquely at a little distance behind the cervix, 

 with the exception of the ornithoryncus and 

 rnonotrematous animals generally ; in these the 

 ureters open into the urethra a little beyond or 

 anterior to the cervix of the bladder, so that 

 the urine must return or ascend, in order to 

 enter its cavity; this curious arrangement is 



similar to that adopted in the chelonia, and 

 would appear to indicate, as Carus ingeniously 

 suggests, that in these strangely formed animals, 

 in the same manner as in reptiles and in birds, 

 the allantois (the remains of the urachus of 

 which form the bladder in mammalia) arises 

 from the expansion of the rectum or the cloaca, 

 whilst in other quadrupeds it is solely connected 

 to the genital passages. In all mammalia this 

 organ presents a tolerably uniform appearance 

 both as to structure and shape, but great diver- 

 sity as to capacity or size ; the latter appears to 

 be in an inverse ratio to its muscularity : hence 

 in Carnivora, the bladder being more muscular, 

 appears smaller in proportion to the size of the 

 animal than in some of the Herbivora, where 

 its coats are thinner, and therefore more dila- 

 table ; in others, however, of the latter order, 

 in whom it is very muscular, its capacity is 

 inferior to that of some even of the carnivora : 

 in the llodentia it is muscular and small, par- 

 ticularly if contrasted with the genital appa- 

 ratus. In quadrupeds the bladder is usually 

 more covered by the peritoneum, and hence it 

 appears more loose and free in the abdomen 

 than in the human subject; its figure is usually 

 rounded, pyriform, or oval ; and it may be re- 

 marked (and the remark will even apply to the 

 human child and embryo) that the younger the 

 animal the more elongated is the bladder, a 

 fact which is indicative of its derivation from, 

 or original continuity with the urachus and 

 allantois. 



THE URINARY BLADDER IN MAN is deeply 

 seated in the anterior inferior part of the pelvis : 

 it is composed of different tissues, membranous 

 and muscular, both calculated to yield and 

 to expand to a slightly distending force, so as 

 to form a recipient reservoir, while the latter is 

 fitted by its contractile power to obliterate the 

 cavity of the organ, and forcibly to eject its 

 contents. This musculo-membranous viscus 

 demands the particular attention of the surgical 

 anatomist, not merely as to its structure, but 

 as regards its situation and connections, as it 

 is the seat of many very severe and often fatal 

 morbid affections, several of which admit of a 

 perfect cure, and most of considerable relief, 

 from operation and from various kinds of local 

 treatment, the safe performance and judicious 

 application of which greatly depend on a cor- 

 rect knowledge of the structure and relations 

 of the organ. We propose first to consider 

 the form and structure of the bladder in the 

 normal state, and afterwards to describe its 

 situation and connections. 



Shape. The figure of the bladder must 

 vary according to its state of contraction or 

 distention, in reference to which it is usual 

 to consider it under three conditions, viz. 

 the empty or contracted, the full or ordina- 

 rily distended, and the over-distended. Its 

 figure in these different states also varies ac- 

 cording to the sex and age of the individual, 

 the bladder of the infant differing materially 

 from that of the adult, and that of the adult 

 female from that of the male ; the bladder of 

 the embryo also differs from that of the fully 

 developed foetus. The ygunger the animal, the 



