THE ABDOMEN 853 



sinus pocularis, or immediately within the lateral margin. For 

 the structure and development of the conunon ejaculatory ducts, 

 see Index. 



Prostate Gland. — This gland surrounds the neck of the bladder, 

 as well as the first i\ inches of the urethra. It is firm in consistence, 

 and in shape and colour resembles a chestnut — that is to say, it 

 is conical and of a reddish-brown colour. It is subject to much 

 variety in size, but its average measurements may be stated as 

 follows : the transverse diameter at the base is about i^ inches ; 

 the vertical diameter from base to apex is about i\ inches ; and 

 the antero-posterior diameter is about J inch. The average weight 

 of the organ is about 4^ drachms. 



The gland is situated fully i^ inches from the anus, and its 

 anterior surface is about | inch behind the lower part of the 

 symphysis pubis. It presents a base, an apex, a posterior or rectal 

 surface, an anterior or pubic surface, and two lateral surfaces. 

 The base, which is directed upwards, surrounds the neck of the 

 bladder, and is intimately connected with the vesical wall. Not- 

 withstanding this, however, there is a superficial line of demarcation 

 between the two, which takes the form of an aimular groove, 

 occupied by a portion of the prostatic venous plexus. The common 

 ejaculatory ducts enter the base close to the upper part of the 

 posterior or rectal surface, where there is a small transverse cleft, 

 called the prostatic fissure. The apex is directed downwards, and 

 is the most dependent part of the organ. It is in contact with the 



¥ostero- superior layer of the triangular ligament of the urethra, 

 he posterior or rectal surface is flat and triangular. It is directed 

 backwards and slightly downwards, and is set upon the anterior 

 wall of the rectum, from which it is separated by the recto-prostatic 

 lamina of the visceral portion of the pelvic fascia. This surface is 

 accessible to manipulation on introducing the finger into the anal 

 canal, and carrying it up for fully ih inches. The anterior or pubic 

 surface, which is convex, is so much projected as to be really an 

 anterior round border, which separates the two lateral surfaces. It 

 lies about \ inch behind the lower part of the symphysis pubis, from 

 which it is separated by a portion of the prostatic venous plexus, 

 the retro-pubic pad of fat, and the pubo-prostatic ligaments. The 

 anterior surface projects between the anterior borders of the leva- 

 tores ani muscles. The lateral surfaces are convex, and stand out 

 in full relief. Each is embraced by the anterior fibres of the corre- 

 sponding levator ani, which constitute the so-called levator pros- 

 tatae muscle. When an accessory pudic artery is present it passes 

 over the lateral surface, and might be endangered in lateral 

 lithotomy. 



The gland is usually regarded as composed of three lobes, two 

 lateral and a middle, but, though the middle lobe can usually be 

 demarcated without much difficulty, there is no external indication 

 of any separation between the lateral lobes. The lateral lobes 

 form the chief bulk of the gland, and they meet and become con- 



