Download File

Male Internal Genital Organs
Pelvis & Perineum Unit
Lecture 3
‫ حيدر جليل األعسم‬.‫د‬
Vas Deferens
It is thick-walled tube about 45 cm
long that conveys mature sperm
from epididymis to ejaculatory
duct and urethra. It arises from
lower end or tail of epididymis and
passes through inguinal canal. It
emerges from deep inguinal ring
and passes around lateral margin
of inferior epigastric artery. It then
passes downward and backward
on lateral pelvic wall and crosses
ureter in region of ischial spine.
Vas deferens then runs medially
and downward on posterior
surface of bladder. Terminal part of
vas deferens is dilated to form
ampulla of vas deferens. Inferior
end of ampulla narrows down and
joins duct of seminal vesicle to
form ejaculatory duct.
Seminal Vesicles
They are two lobulated organs
about 5 cm long lying on posterior
surface of bladder. On medial side
of each vesicle lies terminal part of
vas deferens. Posteriorly, seminal
vesicles are related to rectum.
Inferiorly, each seminal vesicle
narrows and joins vas deferens of
same side to form ejaculatory duct.
Blood Supply:
Arteries: inferior vesicle and middle
rectal arteries.
Veins: drain into internal iliac veins.
Lymph Drainage: internal iliac nodes
Function: produce a secretion that
nourishes spermatozoa. During
ejaculation seminal vesicles contract
and expel their contents into
ejaculatory ducts, thus washing
spermatozoa out of urethra.
Ejaculatory Ducts
They are short (less than 2.5 cm) long and are formed by union of vas
deferens and duct of seminal vesicle. Ejaculatory ducts pierce posterior
surface of prostate and open into prostatic part of urethra, close to
margins of prostatic utricle; their function is to drain seminal fluid into
prostatic urethra.
Prostate
It is a conical fibromuscular glandular organ that surrounds prostatic
urethra. It is about 3 cm long and lies between neck of bladder above
and urogenital diaphragm below. Prostate is surrounded by a fibrous
capsule and has base, which lies against bladder neck above, and apex,
which lies against urogenital diaphragm below. The two ejaculatory
ducts pierce upper part of posterior surface of prostate to open into
prostatic urethra at lateral margins of prostatic utricle.
Relations of Prostate
Superiorly: bladder neck, smooth muscle
passing without interruption from one
organ to other. Urethra enters center of
base of prostate.
Inferiorly: upper surface of urogenital
diaphragm. Urethra leaves prostate just
above apex on anterior surface.
Anteriorly: Symphysis pubis (separated
by extraperitoneal fat in retropubic space
(cave of Retzius). Prostate is connected to
posterior aspect of pubic bones by fascial
puboprostatic ligaments.
Posteriorly: anterior surface of rectal
ampulla (separated by rectovesical septum
- fascia of Denonvilliers) formed in fetal life
by fusion of walls of lower end of
rectovesical pouch of peritoneum.
Laterally: prostate is embraced by anterior
fibers of levator ani as they run posteriorly
from the pubis (levator prostatae).
Lobes of Prostate
It is incompletely divided into five
lobes:
Anterior lobe lies in front of
urethra & is devoid of gland tissue.
Median, or middle, lobe is wedge
of gland situated between urethra
and ejaculatory ducts. Its upper
surface is related to trigone of
bladder and projects into forming
uvula vesicae; rich in glands.
Posterior lobe is situated behind
urethra & below ejaculatory ducts
& also contains glandular tissue.
Right and left lateral lobes lie on
either side of urethra and are
separated from one another by a
shallow vertical groove on
posterior surface of prostate.
Lateral lobes contain many glands.
Lobes of Prostate
Blood Supply
Arteries: inferior vesical and
middle rectal arteries.
Veins: prostatic venous plexus,
which lies outside the capsule
of prostate. Prostatic plexus
receives deep dorsal vein of
penis and numerous vesical
veins and drains into internal
iliac veins.
Lymph Drainage:
Internal iliac nodes.
Nerve Supply: Inferior
hypogastric plexuses.
Sympathetic nerves stimulate
smooth muscle of prostate
during ejaculation.
Prostatic Urethra
It is about 3 cm long and begins at bladder neck. It passes through
prostate from base to apex, where it becomes continuous with
membranous part of urethra. Prostatic urethra is the widest and most
dilatable portion of entire urethra. On posterior wall is a longitudinal
ridge called urethral crest. On each side of this ridge is a groove called
prostatic sinus; prostatic glands open into these grooves. On summit of
urethral crest is a depression,
prostatic utricle, which is an
analog of uterus and vagina
in females. On edge of mouth
of the utricle are openings of
the two ejaculatory ducts.
Male Pelvic Peritoneum
Peritoneum passes down from anterior abdominal wall onto upper
surface of urinary bladder. It then runs down on posterior surface of
bladder for a short distance until it reaches upper ends of seminal
vesicles. Here it sweeps backward to reach anterior aspect of rectum,
forming shallow rectovesical pouch. Peritoneum then passes up on
front of middle third of rectum and front and
lateral surfaces of upper third of rectum.
It then becomes continuous with parietal
peritoneum on posterior abdominal wall.
Rectovesical pouch is the lowest part
of abdominopelvic peritoneal cavity
in erect position.
Peritoneum covering superior surface of
bladder passes laterally to lateral pelvic
walls and does not cover lateral surfaces
of bladder. It is important to remember that
as bladder fills, superior wall rises up
into abdomen and peels off peritoneum from
anterior abdominal wall so that bladder
becomes directly in contact with abdominal wall.
Thank You