The anterior surface, which is grooved by a shallow longitudinal depression, is attached to the back part of the symphysis pubis on either side by two ligamentous or tendinous bands, which are continuous with the cap sule of the gland below, and above with the true anterior ligaments of the bladder ; they are termed the liganzenta pubo-prosta. nzedia et lateralia ; they serve to support the prostate and sling it to the pubis, thus contributing to the support of the neck of the bladder. The posterior surface of the pros tate is smooth and is traversed by a lorwitudi nal depression, at the bottom of which two smaller grooves are visible, inclining towards each other in front, they bound two sides of a small triangalar portion of the gland ; this is the under surface of the third lobe on either side of wbich a vas ejaculatoriuni t'akes its course.
The prostate is surrounded by a dense capsule derived from the vesical fascia; this gives it a complete investment, and adheres so firmly to the tissue of the gland as to be separated from it with great difficulty. It is divisible into two layers, between which the prostatic plexus of veins runs. The gland itself is of a lightish brown colour, of a fleshy feel, and when cut it offers the resistance ot soft cartilage : it is one of the firmest glands in the body. It is principally formed of two lateral lobes, a rik,,ht and a left, of equal size in the healthy condition, of an ovoid shape, with their long axes from before backwards ; they diverge from each other behind, leaving an in terval between them, already. mentioned ; the lateral lobes are connected together beneath the urethra by an isthmus of variable depth and breadth. Between the two lateral lobes, which make up the bulk of the gland, we find the middle or third lobe. The name of Sir Everard Home is usually associated with the description ofthis lobe. Although not the dis., coverer of it, he gave the first full description of it. Mr. (now Sir Benjamin) Brodie made dissections of it under Home's direction ; in the first subject in which it was examined, it appeared as a distinct gland, resembling Cow per s gland in size and shape ; but in the ex,. amination of this body in five different subjects, the appearance was not the same in any two of them. The following is the account given by Home of what he considers the most natural condition of this part of the prostate : — " On turning off the vasa deferentia and vesiculre seminales, exactly in the middle of the sulcus, between the two lateral portions of the prostate gland, there was a round, pro minent body, the base of which adhered to the coats of the bladder. It was imbedded not only between the vasa deferentia and the blad der, but also in some measure between the lateral portions of the prostate gland and the bladder, since they were in part spread over it, so as to prevent its circumference from being seen, and they adhered so closely as to require dissection to remove them ; nor could this be done beyond a certain extent, after which the same substance was continued from the one to the other. This proved to be a
lobe of the prostate gland ; its middle had a rounded form, united to the gland at the base next the bladder, but rendered a separate lobe by two fissures on its opposite surface. Its ducts passed directly through the coats of the bladder on which it lay, and opened immedi ately behind the veru montanum." It is well known that Hunter was aware of the existence of this lobe as a natural consti tuent of the prostate, for he says, " A small portion of it (the prostate) which lies behind the very beginning of the urethra, swells for ward like a point, as it were, into the blad. der ; acting like a valve to the mouth of the urethra, which can be seen even when the swelling is not considerable, by looking on the mouth of the urethra, from the cavity of the bladder in the dead body. It sometimes in creases so much, as to form a tumor project ing into the cavity of the bladder some inches." Hunter has given dn accurate draw ing of the middle lobe of the prostate. In the normal state it represents a simple elevation of glandular structure beneath the uvula vesicm, between the two lateral lobes at the back part, and connected laterally with them ; but it varies materially in size and consistence in different subjects. I have no doubt that in some cases it is wanting altogether, in others it is of small size; and in many, where it is well developed, it is as firm and consistent as the other parts of the prostate. In one ex ample which I examined, it was much firmer than the lateral lobes, and of a much lighter colour ; indeed, so distinct did it appear that I really doubted whether it belonged to the prostate. I applied a microscopical test, and found its ducts charged with similar concre tions to what have been so frequently found in other parts of the gland ; this proved to me that it was a part of the gland itself. The best method of viewing the third lobe is to make a vertical section from before backwards through it, and to carry the incision directly through the veru montanunz, sinus pocularis, urethra, and inferior part or isthmus of the prostate, the divided third lobe is thus brought into view, as well as the ejaculatory duct of one side, passing between it and the lateral lobe. The sinus pocularis runs beneath it (see fig.101).