1304 THE URO-GENITAL SYSTEM. 



smooth muscular fibres, which is continued upwards and backwards on the sides of the 

 urethra to form a part of the " sphincter vesicse." At a lower level striped muscular 

 tissue, which is continuous with the deep part of the sphincter urethras membranacese 

 muscle, occupies a position in front of the urethral canal. 



The muscular tissue of the prostate is to be regarded as the thickened muscular 

 layer of the wall of the urethra, broken up and invaded by the prostatic glands 

 which arise and are developed from the lining layer of the canal during embryonic life. 



In old age the prostate frequently undergoes a hypertrophy, which may affect chiefly 

 the glandular tissue, or the entire organ. Not infrequently calcareous concretions are 

 found embedded in the prostate. 



Vessels and Nerves of the Prostate. The prostate receives its blood -supply from branches 

 of the haemorrhoidal and inferior vesical arteries, while the large plexus of veins plexus pudendalis 

 which surrounds it, and into which the veins of the penis open, communicates with the vesical 

 plexus, and drains into the hypogastric veins. In old people the veins of the prostate usually 

 become much enlarged. 



The nerves of the prostate are derived from the hypogastric plexus. 



GLANDULJE BULBO-URETHRALES. 



The bulbo-urethral glands (O.T. glands of Cowper) are a pair of small bodies 

 placed in relation to the second, or membranous, part of the urethra. They are 

 each about the size of a pea, and are of a yellowish-brown colour. Situated 

 in the space between the two fasciae of the urogenital diaphragm, they lie 

 below the level of the apex of the prostate, and above that of the bulbus urethrae 

 (Figs. 1024 arid 1026). Each gland is made up of a number of closely applied 

 lobes or lobules, and is of the compound racemose type. The ductules -of the gland 

 unite to form a single ductus excretorius, which pierces the bulbus urethrse, and, 

 after a relatively long course, ends by opening into the cavernous portion of the 

 urethra by a minute aperture. The secreting acini are lined with columnar 

 epithelium. 



The glands receive their arterial supply from the artery to the bulb. 



In old age these glands are often difficult to find without a microscopic examination. 



URETHRA VIRILIS. 



The urethra in the male is a channel of about eight inches in length leading 

 from the bladder to the external urethral orifice at the extremity of the glans 

 penis. The canal serves not only for the passage of urine, but it also affords an 

 exit for the seminal products, which enter by the ejaculatory ducts, and for the 

 secretion of the prostatic and bulbo- urethral glands. In addition, numerous 

 minute glandulse urethrales pour their secretion into the urethra. 



As it passes from the internal urethral orifice, to its external opening, the 

 urethra describes a somewhat LP shaped course, and it is customary to divide it into 

 certain sections, which have received distinctive names. The first part of the 

 urethra lies within the pelvic cavity, and has a somewhat vertical course as it 

 traverses the prostate. Turning more forwards, the urethra passes below the 

 pubic arch, and pierces the fibrous layers which form the pelvic wall in this 

 region. Leaving the pelvis minor, the canal enters the bulbus urethrse, where 

 the latter is attached to the fascia inferior of the urogenital diaphragm, and 

 throughout the rest of its course it lies in the erectile tissue of the corpus caver- 

 nosum urethras and of the glans penis. The part of the urethra which lies 

 embedded' in the prostate is called the pars prostatica, or prostatic portion ; the short 

 part which pierces the pelvic wall is called the pars membranacea, or membranous 

 portion, and the part surrounded by the corpus cavernosuin urethras receives the 

 name of pars cavernosa, or cavernous portion. Of these three sections of the urethra 

 the cavernous portion is much the longest, and the membranous is the shortest. 



