THE PROSTATE. ag Ly 
The upper surface, or base of the prostate (basis prostate), is directed upwards 
against the under aspect of the bladder, in the neighbourhood of its urethral open- 
ing. The greater part of this surface is structurally continuous with the bladder 
wall, the separation of the two organs being purely artificial. A narrow portion 
of the superior surface is, however, free on each side, and forms the lower limit of 
the deep groove which marks the separation of the bladder and prostate (Fig. 
763). The lateral surface of the prostate is convex and prominent, especially in 
its posterior and upper portion, and rests against the fascia covering the levator 
ani muscle. The lateral surfaces are directed for the most part outwards, down- 
wards, and somewhat forwards, and meet together in front in a rounded anterior 
border, often called the “anterior surface” (facies anterior) of the prostate. 
Posteriorly the prostate presents a flattened triangular area, directed backwards and 
downwards against the anterior wall of the rectum, from which it is separated by a 
layer of the pelvic fascia. This flattened posterior surface (facies posterior) is 
separated on each side from the lateral surface by a rounded border which, begin- 
ning above at the prominent lateral part of the prostate, ends below at the apex 
of the organ. The apex of the prostate (apex prostate) points downwards, and is 
in relation to the deep or superior 
layer of the triangular ligament. From 
the apex the rounded anterior border, 
which separates the lateral surfaces, 
passes upwards in the middle line 
behind the symphysis pubis and retro- 
pubic pad of fat. This border is inter- 
rupted in its lower part by the passage 
of the urethra. 
The urethra enters the prostate at 
—Bladder apex 
Infero-iateral 
area 
Urethra 
: ° 5 ji /Ureter 
a point near the middle of its upper me | L/ : 
rae & 
surface, and leaves it at a point situated = 
on its anterior border, just above and | ee 
in front of the apex. As it descends, deferens 
the urethra describes a curve which 2a 
is concave forwards, and in mesial Seminal vesicle 
section it is seen to he nearer to the Fig. 764.—PROsTATE, BLADDER, AND SEMINAL 
posterior surface than to the anterior VESICLES SEEN FROM BELOW. 
border of the eland. Drawn from a specimen hardened in situ. The lateral 
surfaces of the prostate are seen one on each side of 
7 16 > ‘ ay ava Ita an 
The common ejaculatory ducts, a the urethra and in front of the posterior surface. 
tering the prostate at the border which 
separates the base from the posterior surface, run downwards, inwards, and forwards, 
to open into the prostatic portion of the urethra very close to one another. The 
somewhat wedge-shaped portion of the prostate, which lies between these ducts and 
the posterior aspect of the urethra, receives the name of middle lobe (lobus medius, 
Fig. 766). The base of this middle lobe projects upwards against the bladder, and 
is continuous with the part of the bladder wall lying immediately behind the 
urethral orifice. When hypertrophied (as it often is in old people) the middle lobe 
of the prostate may cause a considerable elevation in the cavity of the bladder, to 
which the term uvula vesice is applied, and which possesses considerable surgical 
interest. The rest of the prostate is described as being composed of two large 
lateral portions or lateral lobes, which are, however, not marked off from one another 
superficially. 
The prostate is surrounded in front and laterally by a plexus of large veins 
which lies embedded within its capsule, and is called the prostatic venous plexus. 
Structure of the Prostate.—The greater bulk of the prostate is composed of 
unstriped muscle fibres. The muscular tissue not only forms the outer layers of 
the prostate, but it also sends into the deeper parts numerous processes which 
spread through the whole structure as a network, in the meshes of which the 
glandular part of the organ is contained. Posteriorly some of the muscle fibres are 
continuous with those of the bladder. The glandular tissue (corpus glandulare) 
of the prostate, which is practically confined to the part of the organ which lies 
