tried to describe anatomy of prostate in a nutshell with few recent concepts

1. Dr. Sambit Tripathy

2. It is humbling to realise that even
today basic anatomy may not be
known or all understood.
-patrick c walsh, 1998

3. Gross Anatomy
 Ovoid (Almond) in shape.
 3 cm in length, 4 cm in width, and 2 cm in depth.
 Weight of 18 to 20 g.
 Homologous to the Skene glands.
 Composed of
1. Glandular elements (70%)
2. Fibromuscular stroma (30%)

4. 3 cm
4 cm
2 cm

5.  The base of the prostate is at the bladder-prostate
junction.
 Apex is the narrowest and the most inferior portion of
the prostate gland.
 Sits on urogenital diaphragm.
 Palpable on DRE (~ 4 cm).

6.  Apex continuous with the striated urethral sphincter.
 It has 3 surfaces
1. Anterior surface
2. Posterior surface
3. Lateral surfaces

7. Capsule of Prostate
 Composed of collagen, elastin, and smooth muscle.
 The capsule measures 0.5 mm in thickness posteriorly
and laterally on average.
 No true prostatic capsule at
1. Apex of the prostate (normal prostate glands are
seen blending into the striated muscle of the
urethral sphincter).
2. At the base separating the prostate from the bladder,
(detrusor muscle fibers fuse with the capsule of the
prostate).

8. Fascia and prostate attachments
 Three separate fascial structures surround the
prostate.
1. Denonvilliers' fascia
2. The prostatic fascia
3. The endopelvic fascia

9. Denonvilliers' fascia
 “The plane between wind and water” - R. Ger, 1988
 Denonvilliers' fascia lies posteriorly, adherent to the
prostate, between it and the rectum.
 It also covers the posterior surface of the seminal
vesicles.
 Denonvilliers' fascia forms an important barrier to
the spread of prostatic and rectal malignancy.

11. Prostatic fascia
 The prostatic fascia surrounds the prostate gland.
 Anteriorly and antero-laterally, it is in direct continuity
with the fibromuscular stroma of the prostate.
 Laterally, it fuses with the endopelvic fascia.
 Posteriorly, it fuses with, and is indistinguishable
from, Denonvilliers' fascia.

12. Endopelvic fascia
 Endopelvic fascia refers to the parietal pelvic fascia in
the region of the prostate, overlying the levator ani
muscle.
 The prostate capsule blends with the continuation of
the endopelvic fascia on the anterior and anterolateral
aspects of the prostate.
 The prostate receives its blood supply and autonomic
innervation between the layers of endopelvic fascia
and the prostatic fascia.

13. Detrusor apron and the
puboprostatic ligaments
 The detrusor apron of Myers is an extension of the
longitudinal smooth muscle of the bladder (detrusor)
anteriorly, in front of the anterior commissure (isthmus) of
the prostate.
 It consists of a loose conglomeration of longitudinal
smooth muscle bands and veins.
 Its thickness is greatest at the bladder neck in the mid-line.
 Laterally, it fuses with the fascial tendinous arch of the
pelvis.

15.  It represents a direct continuity of the anterior wall of
the bladder with the pubis, via the puboprostatic
ligaments, similar to that in the female.
 The superficial branch of the dorsal vein is positioned
in the retropubic fat outside the prostatic fascia. It
drains into the dorsal vein complex.

17.  The levator ani's pubococcygeal portion hugs the
lateral aspects of the prostate and is related to its
overlying endopelvic fascia .
 The prostate capsule and the pelvic fascia separate
below the parietal and visceral endopelvic fascia
juncture (arcus tendineus fascia pelvis).

18. Neurovascular bundle of Walsh
 Fatty, areolar tissue and the lateral branches of the
dorsal vein complex take up the space of this
separation between the prostate capsule and the pelvic
fascia.
 The cavernosal nerves travel within the parietal
pelvic fascia, also known as the lateral prostatic
fascia, posterolateral to the prostate.

20. Zones of prostate
 The prostate has been divided into distinct
anatomic zones.
 Can be identified with TRUS.
1. Transition zone
2. Central zone
3. Peripheral zone

21. Transition zone
 Transition zone is the smallest of the zones of the
prostate.
 5% to 10%.
 The transition zone is separated from the rest of the
glandular compartments of the prostate by a distinct
fibromuscular band.
 Benign prostatic hyperplasia most commonly occurs in
the transition zone.

23. Central zone
 The central zone ducts are positioned
circumferentially, surrounding the openings of the
ejaculatory ducts.
 This zone expands toward the base of the bladder,
surrounding the ejaculatory ducts, in the shape of a
cone.
 The central zone comprises 25% of the glandular tissue
of the prostate.

24. Peripheral zone
 The peripheral zone of the prostate is the largest
zone (70%).
 Makes up the posterior and lateral aspects of the
prostate gland.
 The ducts of the peripheral zone drain into the
prostatic sinus along the entire length of the
postsphincteric prostatic urethra.
 Seventy percent of prostate cancers are found in the
peripheral zone.

25. Anterior fibromuscular stroma
 Non-glandular
 May comprise up to one third of the mass of the
prostate.
 Composed of collagen, smooth and striated muscle,
and elastin.
 It is anatomically continuous with the anterior visceral
fascia, the anterior preprostatic sphincter, and the
prostatic capsule.

26.  Compartmentalized clinically, based on digital rectal
examination and cystoscopic appearance.
 A central sulcus divides the two lateral lobes of the
prostate and a middle lobe.
 The middle lobe may become hyperplastic and may
extend into the bladder neck with age.

27. Histology
 The epithelial cells of the prostate glands are cuboidal
or columnar.
 These epithelial cells have abundant secretory granules
and are organized in rows with their apices projecting
into the lumen and their bases attached to a basement
membrane.
 The epithelial cells line the periphery of the acinus and
secrete into the acinus, which drain into ducts to the
urethra ultimately.

29.  A thin layer of connective tissue and stromal smooth
muscle surrounds each acinus.
 The stroma is composed of smooth muscle, which is
rich in α-actin, myosin, and desmin.
 It is also composed of collagen and is continuous with
the prostatic capsule.

30. Arterial Supply
 The inferior vesical artery is the typical arterial
supply to the prostate.
 The inferior vesical artery branches into urethral
arteries that enter the prostatovesical junction
posterolaterally and course in a perpendicular route to
the urethra.
 They travel toward the bladder neck with the largest
branches posteriorly, approaching the bladder neck in
the one o'clock to five o'clock positions and the seven
o'clock to eleven o'clock positions.

31.  They then supply the urethra after making a caudal
turn to run parallel to the urethra.
 These branches supply the urethra, the periurethral
glands, and the transition zone of the prostate.

33.  The inferior vesical artery also branches into the
capsular artery.
 The capsular artery yields small branches that supply
the anterior prostatic capsule.
 The capsular branches enter the prostate at 90-degree
angles and provide arterial supply to the glandular
tissues.

34.  Also supplied by banches from
1. Internal pudendal artery
2. Middle rectal (hemorrhoidal) artery

35. Venous Drainage
 The prostate includes abundant venous drainage
through the periprostatic plexus.
 The periprostatic plexus anastomoses with the deep
dorsal vein of the penis and the internal iliac
(hypogastric) veins.
 Batson venous plexus (or Batson veins) is a
network of veins with no valves that connect deep
pelvic veins draining the bladder, prostate,
and rectum to the internal vertebral venous plexus.

37. Lymphatic Drainage
 The obturator and internal iliac nodes are the
primary sites of lymphatic drainage from the
prostate.
 The presacral group or, infrequently, the external iliac
nodes may receive a small portion of the initial
lymphatic drainage.

38. Nerve Supply
 The cavernous nerves provide sympathetic and
parasympathetic innervation to the prostate from the
pelvic plexus.
 Innervations to the glandular and stromal elements of
the prostate are found traveling with branches of the
capsular artery.
 Sympathetic fibers innervate the smooth muscle of the
capsule and stroma for contraction.

39.  The parasympathetic nerves promote secretory
function by terminating in the acini.
 The pelvic plexuses carry afferent neurons from the
prostate to the pelvic and thoracolumbar spinal
centers.

41. DETRUSOR APRON
 In pictorial review of his operation, Walsh clearly
demonstrated the existence of the obscuring tissue
proximal to an underlying right-angle clamp and a
single silk ligature to secure the dorsal vein complex.
 The tissue that obscures the prostate in part
constitutes an extension of the anterior wall of the
bladder beyond the point at which the bladder neck is
formed.
 It is a detrusor apron, which has been described or
illustrated, but has generally been unappreciated with
respect to radical prostatectomy.

43.  There continues to be a misconception in the minds of
many urologists that the bladder ends anteriorly at the
bladder neck.
 The mistaken concept, widely believed and illustrated,
is of a bladder perched entirely on top of the prostate,
like a hot air balloon with a gondola beneath.
 Furthermore, the puboprostatic ligaments are
commonly shown attached directly to the anterior
surface of the prostate with no bladder connection.

44.  However, there is direct continuity of the anterior wall
of the bladder with the pubis, similar to the female,
and it should be illustrated that way.
 Understanding the detrusor apron should help
urologists to perform radical prostatectomy with
increased skill.