THE PROSTATE GLAND. 1149 



prostate gland : and by the anterior portion of the Levator ani muscle (levator 

 prostatce), which passes down on each side from the symphysis pubis and anterior 

 ligament of the bladder to the sides of the prostate. 



The prostate consists of two lateral lobes and a middle lobe. 



The two lateral lobes are of equal size, separated by a deep notch behind, and 

 by a slight furrow upon the anterior and posterior surfaces of the gland, which 

 indicates the bilobed condition of the organ in some animals. 



The third, or middle lobe, is a small transverse band, occasionally a rounded or 

 triangular prominence, placed between the two lateral lobes at the posterior part 

 of the organ. It lies immediately beneath the neck of the bladder, behind the 

 commencement of the urethra, and above and between the ejaculatory ducts. Its 

 existence is not constant, but it is occasionally found at an early period of life, as 

 well as in adults and in old age. 



The prostate gland is perforated by the urethra and the ejaculatory ducts. 

 The urethra usually lies about one-third nearer its posterior than its anterior sur- 

 face ; occasionally, the prostate surrounds only the lower three-fourths of the tube, 

 and more rarely the urethra runs through the lower instead of the upper part of 

 the gland. The ejaculatory ducts pass forward obliquely between the middle and 

 each lateral lobe of the prostate and open into the prostatic portion of the urethra. 



Structure. The prostate is enclosed in a thin but firm fibrous capsule, distinct 

 from that derived from the posterior layer of the deep perineal fascia, and separated 

 from it by a plexus of veins. Its substance is of a pale reddish-gray color, of 

 great density and not easily torn. It consists of glandular substance and muscular 

 tissue. 



The muscular tissue, according to Kolliker, constitutes the proper stroma of the 

 prostate, the connective tissue being very scanty, and simply forming thin trabeculae 

 between the muscular fibres, in which the vessels and nerves of the gland ramify. 

 The muscular tissue is arranged as follows : Immediately beneath the fibrous capsule 

 is a dense layer, which forms an investing sheath for the gland : secondly, around 

 the urethra as it lies in the prostate, is another dense layer of circular fibres, 

 continuous behind with the internal layer of the muscular coat of the bladder, 

 and in front blending with the fibres surrounding the membranous portion of the 

 urethra. Between these two layers strong bands of muscular tissue, which 

 decussate freely, form meshes in which the glandular structure of the organ is 

 imbedded. In that part of the gland which is situated above the urethra the 

 muscular tissue is especially dense, and there is here little or no gland tissue; 

 while in that part which is below the urethra the muscular tissue presents a wide- 

 meshed structure, which is densest at the upper part of the gland that is. near 

 the bladder becoming looser and more sponge-like toward the apex of the 

 organ. 



The glandular substance is composed of numerous follicular pouches, opening 

 into elongated canals, which join to form from twelve to twenty small excretory 

 ducts. The follicles are connected together by areolar tissue, supported by 

 prolongations from the fibrous capsule and muscular stroma. and enclosed in a 

 delicate capillary plexus. The epithelium lining of both the canals and the 

 terminal vesicles is of the columnar variety. The prostatic ducts open into the 

 floor of the prostatic portion of the urethra. 



Vessels and Nerves. The arteries supplying the prostate are derived from the 

 internal pudic, vesical, and haemorrhoidal. Its veins form a plexus around the sides 

 and base of the gland ; they receive in front the dorsal vein of the penis, and 

 terminate in the internal iliac vein. The nerves are derived from the pelvic 

 plexus. 



Surgical Anatomy. The relation of the prostate to the rectum should be noted : by means 

 of the finger introduced into the gut the surgeon detects enlargement or other disease of this 

 organ ; he can feel the apex of the gland, which is the guide to Cock's operation for stricture ; 

 he is enabled also by the same means to direct the point of a catheter when its introduction is 

 attended with difficulty either from injury or disease of the membranous or prostatic portions of 



