382 



BLADDER, NORMAL ANATOMY. 



near the neck. Occasionally some of the longi- 

 tudinal fibres alter their direction gradually or 

 abruptly, as may be particularly noticed about 

 the ureters and also on the lateral regions. 

 Great diversity exists as to the arrangement of 

 this tunic in the lower animals : thus in the 

 dog this plane consists of strong and regularly 

 parallel fibres, whereas in the ox they assume a 

 reticular and irregular course : in man they re- 

 semble the arrangement of the carnivorous more 

 than that of the graminivorous animals. This 

 tunic must have the effect of compressing the 

 bladder towards the ossa pubis, and of course 

 urging the contents of the cavity in that direc- 

 tion, while at the same time some of its fibres 

 will expand the orifice of the urethra by draw- 

 ing out the sphincter above and on either side, 

 and below by depressing the uvula and the 

 verumontanum. This stratum of muscular 

 fibres can be raised with a little careful dissec- 

 tion ; a few fibres must be divided, which now 

 and then change their direction, and join some 

 of the deeper orders : this separation is difficult 

 and can be but imperfectly made on the lateral 

 regions, but on the anterior and posterior it can 

 be fully accomplished. The second order of 

 muscular fibres is circular or transverse; they 

 are paler, weaker, and more scattered than the 

 former, particularly towards the superior part 

 of the bladder, where they are often indistinct. 

 As they descend they increase in thickness, par- 

 ticularly near the cervix, where they are so 

 close and distinct as to have induced many to 

 consider them as a sphincter to the bladder, a 

 term, however, to which they do not appear to 

 have been entitled, for there is no distinction 

 between the fibres in this situation and those 

 which have a parallel course at a greater dis- 

 tance ; and inasmuch as the latter are obviously 

 designed to contract the organ and to expel its 

 contents, it is most probable that the former 

 must contribute to the same effect, and forcibly 

 expeL the last drops which it contains : indeed 

 it is impossible to draw such a line of distinc- 

 tion in this lamina as could denote the limit 

 between the expelling and the retaining or 

 sphincter fibres. In addition to this plane of 

 circular fibres, several others may also be ob- 

 served taking a parallel direction ; thus we oc- 

 casionally find transverse bands superficial to 

 the longitudinal plane, both on the anterior and 

 posterior regions in different situations. We very 

 generally also find them near the superior fun- 

 dus, and constantly on the anterior and lateral 

 parts of the neck, where they cover the decus- 

 sation of the longitudinal fibres. In the inter- 

 val between the ureters, these transverse fibres 

 are very distinct, particularly above, where they 

 usually form a very distinct cord, arched a little 

 upwards: this semilunar band or projection 

 may be better seen when the bladder is opened ; 

 it corresponds to the base of the trigone, ex- 

 tends from one ureter to the other, and is im- 

 mediately in front of the pouch or bas fond of 

 the bladder, which is so well marked in the 

 adult and old. Throughout the rest of the 

 trigone the circular fibres are by no means so 

 distinct or strong as they are behind it, or as 

 they are towards the anterior and lateral parts 



of the cervix. This circular plane of fibres may 

 next be raised ; it is almost impossible to do 

 this completely, because many of them deviate 

 from that course, and join into the next or third 

 lamina, taking a totally different course; the 

 separation, however, can be accomplished suffi- 

 ciently to demonstrate the peculiar arrange- 

 ment of the third plane of fibres, not all over 

 the bladder, but only in particular situations, 

 namely, in the greater part of the anterior 

 and posterior regions, but only very imper- 

 fectly on the superior fundus, and on the 

 sides, and not at all on the trigone. W herever 

 this third layer is exposed, the fasciculi appear 

 very large and thick, and present a very remark- 

 able appearance and course, not unlike the 

 inner surface of the cavities of the heart. Large 

 fleshy bundles, bearing some resemblance to 

 the carnese columnse, separate, unite again, and 

 again subdivide, the fibres taking various direc- 

 tions, and inclosing interstices of the mucous 

 surface of various size and form : several of the 

 fibres also join those of the circular plane. It 

 is owing to this reticularly arranged stratum of 

 muscular fibres that the bladder, when opened, 

 presents its peculiar irregular surface, which in 

 some cases, particularly if the bladder have 

 been hardened in alcohol, resembles a honey- 

 comb surface. If the bladder which has been 

 opened be everted, then carefully closed and 

 distended, this reticular coat will become very 

 distinct when the mucous membrane has been 

 removed. Its action during life must obviously 

 be to contract the capacity of the bladder in 

 every direction. When the internal surface of 

 the bladder, even in the healthy state, is in- 

 spected, the different orders of muscular fibres 

 become very apparent; and when this coat has 

 become thickened from any of those causes which 

 are well known to produce thickening, some 

 of the fasciculi often project into the bladder : 

 such a condition of the organ is named a co- 

 lumnar state of the bladder. In cases of irritable 

 bladder, when calculous symptoms have been 

 present, and the bladder has been sounded in 

 consequence, these fleshy projections meeting 

 the extremity of the sound, have in some in- 

 stances deceived the surgeon into the idea of 

 the existence of a calculus, and this is still more 

 likely to occur should there be any gritty mat- 

 ter adhering to their surface. Some of those 

 recorded cases of the operation for lithotomy, 

 in which no stone could be detected, although 

 the symptoms of the disease previously existed, 

 may admit of explanation by a knowledge of 

 this fact. In the bladder of some persons the 

 muscular fibres do not perfectly cover the mu- 

 cous surface, particularly if the organ be very 

 capacious. In such cases the mucous membrane 

 may be pushed through some of the cells en- 

 meshes of the muscular fibres, and thus a hernia 

 of the mucous coat be produced; that is, a small 

 pouch or purse of this membrane will protrude 

 between the muscular fasciculi, and will be 

 covered only by peritoneum or by cellular 

 tissue. This pouch may continue to increase 

 in size, because it possesses no power of empty- 

 ing itself, and the muscular fibres around its 

 orifice can only contract the latter without 



