113 



force with which the urine passes along the ureters, is to that by whicis 

 the parietes of the bladder are distended, as the calibre of the ureters is to 

 the superficies of the bladder. 



The pressure which the urine, accumulated within the bladder, exerts 

 on the lower part of the ureters, does not prevent the force which deter- 

 mines its descent along the ureters, from carrying it into the bladder: 

 for, the column which descends along the ureters, being higher than that 

 contained in the bladder, these two organs represent an inverted syphon, 

 the longer branch of which is represented by the ureter. 



The following are the causes which enable the bladder to retain the 

 urine: the contraction of its sphincter, a muscular ring surrounding the 

 termination of the urethra into the bladder: the angle formed by that 

 canal, after it leaves the bladder; and lastly, the action of the anterior 

 fibres of the levator ani, which surround the neck of that organ, surround- 

 ed besides and supported by the prostate gland. These fibres, which 

 are calculated to compress the prostate over the neck of the bladder, and 

 to raise the latter against the pubis, have been called by Morgagni, fisettdo 

 sphincteres vesicse. 



The urine, deposited by drops into the bladder, gradually separates its 

 parietes. This musculo-membranous organ rises, and at the same time, 

 carries upwards the convolutions of the ileum, and the peritoneum before 

 which it lies, behind the pubis and the recti muscles with which it is in 

 immediate contact. These relations of the peritoneum to the distended 

 bladder, account for the possibility of puncturing it above the pubis, so 

 as to let out an accumulation of urine, without penetrating into the cavi- 

 ty of the peritoneum. The urine remains a certain time in the bladder, 

 according to the capacity of the latter, to the irritability and extensibility 

 of its parietes, and according to the acrid or stimulating qualities of the 

 fluid itself. Thus in old men, in whom the bladder has but a small de- 

 gree of irritability and contractility, the urine is voided less frequently; 

 it accumulates in greater quantity, and is, at times, evacuated with diffi- 

 culty. The use of diuretics, especially of cantharides, renders the urine 

 more stimulating, it excites powerfully the parietes of the bladder, and 

 incessantly stimulates it to contraction. Every cause of irritation seated 

 within the bladder itself, or in its vicinity, renders more frequent the 

 calls to void urine. This is observed in cases of stone in the bladder, of 

 piles, gonorrhsea, See. The urine, while in the bladder, becomes thicker 

 from the absorption of its more fluid parts, its elements become more 

 intimately blended, sometimes even, it appears to undergo a certain de- 

 gree of decomposition. 



XXXV. When, either by the extension which the urine occasions in 

 the muscular fibres of the bladder, or by the irritation which it excites 

 in the nerves distributed on its inner membrane, we experience in the 

 pelvis a sensation of weight, together with a kind of tenesmus, which, as 

 it extends along the urethra, warns us to void urine; then we bring on a 

 contraction of the bladder, and joining to its action, that of the abdomi- 

 nal muscles and of the diaphragm, .we expel the urine by a process very 

 similar to that of the excretion of the faeces, (XXIX.) It should be ob- 

 served, however, that in a healthy state of the parts, this assistance is 

 required, only to overcome the equilibrium between the contractions of 

 the bladder, and the resistance which the cause of retention opposes to 

 the evacuation of the urine. After the simultaneous contraction of the 

 diaphragm and abdominal muscles, to press down the intestines on the 



