1146 THE URINARY ORGANS. 



innocent tumors are the papilloma and the mucous polypus, arising from the mucous membrane ; 

 the fibrous, from the submucous tissue ; and the myoma, originating in the muscular tissue : 

 and, very rarely, dermoid tumors, the exact origin of which it is difficult to explain. Of the 

 malignant tumors, epithelioma is the most common, but sarcomata are occasionally found in the 

 bladder of children. 



Puncture of the bladder may be performed either above the pubes or through the .rectum, 

 in both cases without wounding the peritoneum. The former plan is generally to be preferred, 

 since in puncture by the rectum a permanent fistula may be left from abscess forming between 

 the rectum and the bladder ; or pelvic cellulitis may be set up ; moreover, it is exceedingly 

 inconvenient to keep a cannula in the rectum. In some cases in performing this operation the 

 recto-vesical pouch of peritoneum has been wounded, inducing fatal peritonitis. The operation, 

 therefore, has been almost completely abandoned. 



THE MALE URETHRA. 



The urethra in the male extends from the neck of the bladder to the meat us 

 urinarius. It presents a double curve in the flaccid state of the penis, but in the 

 erect state it forms only a single curve, the concavity of Avhich is directed upward 

 (Fig. 599). Its length varies from eight to nine inches, and it is divided into 

 three portions, the prostatic, membranous, and spongy, the structure and relations 

 of which are essentially different. Except during the passage of the urine or 

 semen the urethra is a mere transverse cleft or slit, Avith its upper and under 

 surfaces in contact. At the orifice of the urethra at the end of the penis the slit 

 is vertical, and in the prostatic portion somewhat arched. 



The Prostatic Portion is the widest and most dilatable part of the canal. It 

 passes through the prostate gland, from its base to its apex, lying nearer its upper 

 than its lower surface. It is about an inch and a quarter in length ; the form of 

 the canal is spindle-shaped, being wider in the middle than at either extremity, and 

 narrowest in front, where it joins the membranous portion. A transverse section of 

 the canal as it lies in the prostate is horseshoe in shape, the convexity being 

 directed upward (Fig. 736) or rather forward, since its direction is nearly vertical. 



Upon the floor of the canal is a narrow longitudinal ridge, the verumont<nnun, 

 or colliculm seminalis, or caput gallinaginis, formed by an elevation of the mucous 

 membrane and its subjacent tissue. It is eight or nine lines in length and a line 

 and a half in height, and contains, according to Kobelt, muscular and erectile tis- 

 sues. When distended it may serve to prevent the passage of the semen backward 

 into the bladder. On each side of the verumontanum is a slightly depressed fossa, 

 the prostatic sinus, the floor of which is perforated by numerous apertures, the 

 orifices of the prostatic ducts, the ducts of the middle lobe opening behind the 

 verumontanum. At the fore part of the verumontanum, in the middle line, is a 

 depression, the sinus pocularis (vesicula prostatica}, and upon or within its margins 

 are the slit-like openings of the ejaculatory ducts. The sinus pocularis forms a 

 cul-de-sac about a quarter of an inch in length, which runs upward and backward 

 in the substance of the prostate beneath the middle lobe ; its prominent upper wall 

 partly forms the verumontanum. Its walls are composed of fibrous tissue, muscu- 

 lar fibres, and mucous membrane, and numerous small glands open on its inner 

 surface. It has been called by Weber, who discovered it, the uterus masculinus, 

 from its being developed from the united ends of the rudimentary Miillerian ducts, 

 and therefore homologous with the uterus in the female. 



The Membranous portion of the urethra extends between the apex of the 

 prostate and the bulb of the corpus spongiosum. It is the narrowest part of the 

 canal (excepting the orifice), and measures three-quarters of an inch along its 

 anterior and half an inch along its posterior surface, in consequence of the bulb 

 projecting backward beneath it. Its anterior concave surface is placed about an 

 inch beneath the pubic arch, from which it is separated by the dorsal vessels and 

 nerves of the penis and some muscular fibres. Its posterior convex surface is 

 separated from the rectum by a triangular space, which is part of the perinamm. 

 The membranous portion of the urethra perforates both the anterior and posterior 

 layers of the deep perineal fascia, and receives an investment from them. As it 

 pierces the posterior layer, the fibres around the opening are prolonged backward 



