K I D N E Y. 



' '■•en the two coats of the bladder, a point which we have 

 -M'ady mentioned in fpeaking of the ureters. 



The bottom of the bladder is a large hollow fituated be- 

 i.ind the triangular fpace, and below the level of the neck : 

 it is, ill faft, the moil depending part of the organ. 



The fides of the bladder become tiiicker in proportion 

 tis the organ csntrafts, and they are rendered thinner when 

 It is dilated. They confill of a ferous, a mufcular, and a 

 mucous coat. 



The firll of thefe invefts only the pofterior region, and a 

 iaial! portion of the lateral regions. In the foetus it covers 

 nlio a fmall part of the front and upper portion of the organ. 

 Its external furface is perfectly fniooth, and moillcned by a 

 ferous fecretion. The internal furface is conneded to the 

 mufcular covering, by cellular fubftance, in fuch a way as to 

 admit with tolerable facility of feparation by direction. 

 This covering is furnifhed by the peritoneum, which palTes 

 from the front of. the abdominal cavity, that is, from the 

 refti mufcles or the ofTa pubis, to the fundus of the bladder, 

 then defcends over the potirior to the inferior iurface of the 

 organ. Here it quits the bladder, and paffes to the front 

 of the reftum in men, to the anterior furface of the uterus 

 in women. As it goes from one to the other of thefe organs, 

 it forms on die fides the two folds improperly called pofte- 

 rior ligaments of tlie bladder, and in the middle a cul-de-fac, 

 which is the loireft portion of the peritoneal cavity in the 

 male fubject. This part may become diftended with the 

 fluid of afcites ; and, as the cul-de-fac jutl mentioned ex- 

 tends to within two or three inches of the anus in many 

 fuhjefts, the paracentelis of the abdomen might be per- 

 formed, in the male fubjeft, from the reftum ; indeed this 

 has been actually done in one inftance. The cul-de-fac 

 formed in the female, by the reflexion of the peritoneum 

 from the vagina to the rectum, would allow a fimilar opera- 

 tion, in that fex, from the pofterior part of the lower furface 

 of the vagina. 



Where tliis ferous covering does not exift, the bladder is 

 covered by a layer of cellular tiffue, the thicknefs and ap- 

 pearance of which are not every where uniform. At the 

 anterior region, behind the pubes, and on the lateral regions, 

 it is very loofe and abundant, and ufually contains more or 

 Icfs fat. At the inferior furface it is lefs copious, but ftill 

 loofe, and contaiiiin.; little or no fat ; a confiderable number 

 of velTels, particularly veins, is feen here. It is denfe and 

 whitilTi about the veficula; feminales and proftate. 



The mufcular coat fiirrounds the bladder at all points ; 

 correfponding, by its external furface, to the ferous tunic, 

 and to the cellular fubftance ; by its internal furface, to the 

 outfide of the mucous coat. It is compofed of a thin ilrn- 

 tuai of pale fibres, difpofed in fafciculi of various fizes, 

 croifing each other in ail direftions, fo as to form a very clofe 

 network, of which the interftices prefent every variety of 

 fize and figure. Ordinarily the mucous coat is completely 

 covered by this mufcular tunic ; but fometimes there are 

 fmall fpaces without any mufcular covering. Through fuch 

 fpaces the mucous membrane may be protruded, fo as to 

 form the cells already mentioned, communicating witli tlie 

 cavity of the bladder. 



An attentive examination of the mufcular fibres Ihews us, 

 that fome have a longitudinal, others a nearly circular direc- 

 tion ; that feveral are oblique, and that the reft compofe an 

 inextricable network. The longitudinal fibres, forming the 

 exterior ftratum, are directed from the neck to the fundus 

 of tlie bladder. The anterior ones arife from the proftate 

 and its covering, and fometimes from the pofterior and in- 

 ferior part of the pubes, and the front ligaments of the 

 bladder; in the female, from tlie poiat of union of the 



Vol. XIX. 



bladder with the urethra ; they afcend over the front of the 

 organ to its upper part, and ^ord to the urachus tlic ex- 

 ternal covering already mentioned. The pofterior fibres 

 form more numerous and larger fafciculi than the anterior : 

 tliey pafs from the urachus, over the pofterior and inferior 

 furfaces, to the proftate in man, and to the junftion of the 

 bladder and vagina in woman. Both thefe portions fend off 

 fibres laterally, which cover the lateral regions, decuftate 

 with euch other, and with thofe of the more deeply-feated 

 ftrata. As all thefe fibres have their fixed poii.ts in the 

 proftate and neck of the bladder, they will draw the other 

 parts of the organ, which are all more or lefs moveable, to 

 the neck, and confequently prcfs the urine againft the orifice 

 of the urethra. 



Tlie obhque fibres are lefs diftinft and mere deeply-feated 

 than the longitudinal ; and are fo blended witii the otherj 

 that it is ahnoft impoftible to obfervc any order in their 

 diftribution. Some have a tranfverfe direction, and embrace 

 the bladder almoft in a circular manner : the more deeply- 

 feated they are, the more they approach to this courfe ; yet 

 feveral longitudinal fafcicuU may be feen in the interior of 

 the organ. The contraftion of thefe fibres diminifties the 

 capacity of the organ in all its diameters, and tends to bring 

 its fides in all direclions towards their common centre. The 

 urine, thus forced on all fides, will efcape in the direftion 

 where there is the leaft refiftance ; that is, the neck of the 

 bladder, againft which it is moreover forced by the con- 

 traction of the longitudinal fibres. 



From its office of expelling the urine, the mufcular coat 

 of the bladder is frequently defcribed as a mufcle, under the 

 name of detrufor urins. It will be readily undcrftood, from 

 the account which we have juft given of its aftion, that the 

 bladder is brought into a flattened ftate, and lies wholly jul 

 behind the pubes, when this covering has contrafted. The 

 fixed point of the organ is behind thofe bones ; the proftate 

 and neck cannot move, and all the other parts are drawn 

 towards them. In this ftate the organ is flattened before 

 and behind, and has a triangular outline ; the fundus forms 

 the apex, the inferior furface the bafis, and the lateral regions 

 the two fides of the triangle. 



In a diftended bladder, the m.ufcular coat is thickeft at 

 the inferior furface and at the bafis ; in other fituations it is 

 often remarkably thinner. This difference arifes from the 

 circumftance, that the coats do not yield equally to diften- 

 tion in all direftions ; for, when we divide a coiitradted 

 bladder, the thicknefs is nearly uniform throughout. 



The dcfcription of the mufcular fibres about the neck of 

 the bladder is ftated very differently by different writers. 

 Some admit, and others deny the exiftcnce of a fphincter 

 veficx, or circular mufcle fura>unding the opening, and 

 clofing it by its contraiSlion. The fibres in tliis fituaiion ate 

 pale, and mixed with feveral veins and cellular texture ; they 

 are certainly completely continuous on all fides with the rell 

 of the mufcular coat. It is obferved by Hallcr, that a 

 fpiiincter was alhgned to the bladder, in the firft inftance, 

 from the fuppofed nccefllty of fuch a ftrudure to account 

 for the funftions, rather than from aftual diflcc'tion ; hence 

 Vefalius places it in front of the proftate. Santorini could 

 find no circular fibres furrounding the mouth of the urethra. 

 Others rcjeft altogether the notion of a fphindler ; aiid Win- 

 flow refers the defcriptions of fuch a part to fafciculi arifing 

 from the pubes. Haller gives tlie following defcription 

 from his own diffeClions. In men tlierc are tranfverfe and 

 even arched fibres above, intricately conncfted together, and 

 lying on the neck of the bladder, on the proftate, and on 

 the longitudinal fibres ariling from the pubes. Others of an 

 arched form, with the concavity towards tlie bladder, l[e 

 5 D under, 



