384 BLADDER, NORMAL ANATOMY. 



mal tissue, except perhaps mucous membranes : by the urine, when only in a moderate quantity, 

 elasticity exists at the pylorus and at the anus, gravitating, not towards the neck, but distending 

 although true muscular and sphincter fibres are the inferior fundus, which lies on a level lower 

 evident at both these outlets. When this region than that of the former, and principally by the 

 is carefully examined in the male subject, we dense muscular, elastic, vascular, and nervous 

 shall find that immediately behind the pubis, on tissue which surrounds three-fourths of the 

 the anterior and lateral reflections of the pelvic orifice of the bladder. The gentle contraction of 

 fascia, to these ligaments numerous muscular the latter raises the uvula into the calibre of the 

 fibres of the bladder are attached ; these are opening, while the remaining sides are pressed 

 chiefly longitudinal, but there are also several into contact with it, and thus the bladder is 

 transverse arched or semilunar, some upon, and closed. When distension excites the usual feel- 

 others underneath the longitudinal fibres, and ing, the muscular coat contracts, the sphincter 

 with which many of them are continuous. None relaxes, phenomena exactly corresponding to 

 of these arched fibres pass around or behind the those which take place under similar circum- 

 prostate so as to encircle this region. The longi- stances in the rectum and anus ; and as the 

 tudinal, the transverse and decussating or inter- levatores ani expand the anal opening by draw- 

 lacing fibres in this situation, are in greater ing the sphincter fibres outwards at the time 

 abundance, and may be raised in successive the expulsive powers of the rectum are dis- 

 laminse. Veins and nerves are very manifest in charging its contents, so the longitudinal fibres 

 and between these ; several of the longitudinal of the bladder draw out from the axis of the 

 fibres of the deeper laminae pass in so deeply as urethral opening the relaxed sphincter which 

 to approach the mucous surface. When the encompasses three-fourths of it, while the 

 several strata of longitudinal fibres have been middle band of the posterior longitudinal will 

 raised from the front and lateral parts of this plainly depress the uvula and expand the orifice 

 region, the circular fibres of the bladder become in that aspect, and will even retract and depress 

 distinct, but do not appear so proportionably the verumontanum, thereby freeing the passage 

 increased as were the longitudinal ; but on de- into the urethra, and retracting that sentient 

 taching more completely the longitudinal strata caruncle from the irritating influence of the 

 down to the circumference of the very opening urinary stream. 



of the urethra, a distinctly fibrous, that is, mus- The next coat of the bladder, the fourth of 

 cular tissue, is evident, bounding this opening some anatomists, or the second common of 

 laterally and superiorly, but not below. This others, is the deep cellular, or more properly 

 muscular fasciculus is not intimately connected the submucous cellular coat, by some also de- 

 to the general circular coat ; it appears redder, nominated the nervous tunic. This coat invests 

 and of a closer texture, and will be found to be the whole organ and connects the muscular and 

 attached to the fibrous or tendinous substance mucous tissues intimately yet loosely ; it con- 

 forming the anterior part of the trigone on each tains no adipose matter, but is very filamentous, 

 side of the uvula, behind which it does not extensible, and elastic : in it are found those 

 pass. The longitudinal fibres are inserted partly vessels and nerves which are to supply the in- 

 into this semicircular muscle, much in the same ternal surface of the bladder, and which, except 

 manner as the levatores ani are inserted into the in some situations, are not very numerous when 

 circumference of the anus. This structure we compared with those in the other hollow vis- 

 consider to be partly elastic, but essentially cera. This coat, though essentially cellular, pre- 

 muscular; it bounds the urethral opening late- sents very many fibrous threads through it, on 

 rally and above, but not below; the slight pro- which much of its strength appears to depend, 

 jection of the uvula in the latter situation, and particularly in those places where the muscular 

 the elasticity and gentle state of contraction coat is deficient. When the bladder is fully 

 natural to all the sphincter muscles, will pre- distended, if we dissect off the muscular fibres 

 serve this opening in a constantly closed state carefully without injuring this tissue, the mu- 

 during the quiescent and normal condition of cous membrane still remains supported ; but 

 the parts. This arrangement is on a level with as soon as a portion of this coat is detached, 

 the uvula, and, of course, behind the orifices of the mucous membrane projects in an unsup- 

 the prostate ducts, although the base of that ported sacculated manner. This coat corre- 

 gland extends further back than this sphincter, sponds with that elastic tissue in the parietes 

 We have repeatedly examined beneath the of the small intestines in some animals, out of 

 uvula for muscular fibres, but have found none which the substance, commonly termed catgut, 

 in a transverse direction ; there is, therefore, no is formed. 



portion of a sphincter in that spot, and hence The third proper coat is the mucous or lining 



one advantage of the slight elevation caused by membrane, to expose which the bladder must 



the uvula and by that portion of the prostate be opened by a perpendicular incision along 



gland denominated its middle lobe, which cor- its anterior region. This tunic is but a portion 



responds to it: indeed sphincter fibres in this of the genito-urinary mucous membrane, and is 



spot would be not only useless, but injurious, as continuous with that lining the ureters above, 



they could scarcely exist without interfering and the urethra below. The vesical portion of this 



with the ejaculatory ducts. We conceive, then, membrane is very thin, has a soft and smooth feel 



that the urine is retained in the bladder partly caused by the mucous fluid which lubricates it; 



by ..iO relaxed or passive state in which its its colour is very pale in the natural condition, 



muscular coats usually remain until they are although in catarrh or in chronic inflammation 



excited by the sense of distension, partly also it presents a general vascular appearance; but 



