THE BLADDER. 491 



2. A middle muscular layer arranged in two orders : a superficial, whose 

 fibres are circular, and a deep, passing in a longitudinal direction. (Leyh 

 and other authorities describe the arrangement of the muscular planes, 

 which are composed of smooth fibres, to be the reverse of this, the longi- 

 tudinal being superficial, and the deep circular.) 



3. An external tunic, composed of connective tissue and elastic fibres. 

 The muscular tissue of the ureter, by contracting, accelerates the flow 



of the urine. 



3. The Bladder. (Fig. 247.) 



Position. This is a membranous reservoir, lodged in the pelvic cavity, 

 where it occupies more or less space, according to the quantity of urine it 

 contains ; it may extend beyond the pubis, into the abdominal cavity. 



Form. Considered in a moderate state of plenitude, the bladder is ovoid 

 in figure ; its large extremity being turned forward, forms a rounded cul-de- 

 sac (fundus), at the bottom of which is remarked a kind of cicatrice, caused 

 by the obliteration of the urachus. The other extremity terminates, 

 posteriorly, by a well-marked constriction, the neck of the bladder, which 

 gives rise to the urethral canal. 



Weight. The average weight of the empty bladder is about sixteen 

 ounces. 



Relations and mode of attachment. The bladder responds: above, to 

 the vesiculee seminales, to the pelvic dilatations of the deferent ducts, as 

 well as to the rectum; below, to the inferior wall of the pelvis, on which it 

 rests (by its base) ; on the sides, to the lateral walls of that cavity. In the 

 female, the superior face of the bladder is in relation with the uterus and 

 vagina, which entirely separate it from the rectum. The posterior extremity 

 or neck (cervix), flanked on each side by the lobes of the prostate, is fixed 

 below to the ischio-pubic symphysis, by means of a particular ligament or 

 fasciculus of elastic and contractile fibres, which are detached from the 

 muscular layer, and expanded over the lower face of Wilson's muscle, to 

 be carried backwards and downwards, and terminate on the surface of 

 the internal obturator muscle. The anterior extremity, or fundus, usually 

 responds to the pelvic curvature of the large colon. 



It is remarked that this extremity is covered by a serous cap, which is 

 prolonged backwards on its body, but further above than below. This 

 covering is continuous with the parietal layer of peritoneum, and adheres 

 closely to the muscular tunic of the bladder, so that it constitutes its chief 

 attachment ; its disposition is precisely similar, in principle, to that of the 

 other serous visceral membranes. 



Thus the peritoneum, after covering the walls of the pelvis, is reflected 

 on the organs contained in that cavity, and in particular on the bladder, 

 around which it forms an orbicular fold. This again gives rise to three 

 secondary folds, a kind of serous layers, which are usually termed the 

 ligaments of the bladder. One of these layers is single and vertical, and is 

 fixed to the inferior part of the fundus ; it is not rare to see it prolonged 

 forward on the lower wall of the abdomen, as far as the umbilicus ; on its 

 free border it is said to have a thin hem or cord, the last vestige of the 

 urachus. If this cord exists, which appears doubtful to us, it cannot possess 

 the signification given to it ; for the urachus has not, like the umbilical 

 arteries, an abdominal portion ; it only commences at the umbilicus to be 

 prolonged in the cord to the allantois. The other two serous layers 

 (umbilical ligaments), pairs and horizontal, are attached to the sides of the 



