Lecture 9: Male genital system(Prostate gland and penis) Flashcards
Prostate Gland: Location
inferior to bladder, anterior to rectum.
The prostate gland surrounds the
prostatic urethra
Prostate Gland: structure
- Fibrous capsule: contains prostatic plexuses of veins and nerves.
➢surrounded by pelvic fascia: forms prostatic sheath, which is continuous anteriorly with the puboprostatic ligaments.
➢Blends posteriorly with rectovesical septum (thicker). - Lobes (anatomically not clearly distinct ):
➢Isthmus: anterior to urethra (fibromuscular).
➢Right and left (glandular): separated anteriorly by isthmus, posteriorly by longitudinal furrow.
➢Subdivided into four lobules (see following slide).
Prostate Gland: Relations
- Base – neck of urinary bladder.
- Apex – in contact with the superior fascia of urethral sphincter & deep perineal muscles.
- Muscular anterior surface – separated from pubic symphysis by retroperitoneal fat in retropubic space.
- Posterior surface – ampulla of rectum.
- Inferolaterior surfaces – related to levator ani muscles.
Prostate Gland: Lobes & lobules:
R and L lobes subdivided into lobules:
Based on relationship to urethra & ejaculatory ducts,
arrangement of ducts and connective tissue.
➢Inferoposterior: posterior to urethra, inferior to ejaculatory ducts. Palpable in digital rectal examination.
➢Inferolateral: lateral to urethra, forms major part of lobe.
➢Superomedial: deep to inferoposterior, surrounds ejaculatory duct.
➢Anteromedial: deep to inferolateral, lateral to proximal prostatic urethra.
* Clinicians: peripheral, central zones, transitional zones: transitional is site of benign prostatic hypertrophy.
Prostatic urethra contains
Prostatic ducts open into prostatic sinuses – on either side of seminal colliculus on the posterior wall of the prostatic urethra.
Seminal colliculus
is an eminence in the middle of the urethral crest.
Urethral crest is a
median ridge between the bilateral grooves called the prostatic sinuses.
➢ prevents backward flow of semen into bladder.
Prostatic utricle
a small slit on the seminal colliculus.
➢Embryological remnant of the uterovaginal canal (forms uterus & part of vagina in females).
Opening of ejaculatory ducts
below utricle.
Prostatic fluid: contributes
20% to volume of semen.
Reproductive and urinary tracts merge in
the prostatic urethra.
Prostate Gland: Arterial supply
- Prostatic arteries arise from branches of internal iliac artery:
➢Inferior vesical arteries, internal pudendal, middle rectal.
Prostate Gland: Venous Drainage
- Veins draining prostate gland form a plexus around the sides and base:
➢Prostatic venous plexus
➢Located between the fibrous capsule
of prostate and the prostatic sheath. ➢Continuous superiorly with the vesical
plexus.
➢Communicates posteriorly with the
internal vertebral venous plexus. ➢Drains into internal iliac veins.
Prostate Gland: Innervation
- Sympathetic – T12-L2, lumbar splanchnic nerves, hypogastric and pelvic plexuses.
- Stimulates secretion from the prostate during ejaculation.
- Parasympathetic - pelvic splanchnic nerves, inferior hypogastric, pelvic plexuses.
- Prostatic plexus is connected with pelvic plexus.
- Gives rise to cavernous nerves: supply erectile tissues of penis (erection) - parasympathetic.
Prostate Gland: Lymphatic
- Lymph draining prostate gland drains to internal iliac nodes.
Penis is the male
copulatory organ.
Penis location
in the urogenital triangle of the male perineum
The penis is the common
outlet for urine and semen.
The penis consists of a
root, body, and glans.
Anatomical position of penis = erect:
➢Dorsal and ventral surfaces.
Three cylindrical bodies of erectile cavernous tissue:
- Corpora (plural) cavernosa – paired and dorsally:
➢ Separated by septum. - Corpus (singular) spongiosum –single and ventrally:
➢ contains spongy/penile urethra. - Each erectile tissue is surrounded by fibrous covering:
➢ tunica albuginea - Deep fascia of penis binds corpora together: continuation of deep perineal fascia.
Penis: root is the
attached part
Penis: root consists of
crura (plural), bulb, ischiocavernosus & bulbospongiosus muscles.
Penis: root location
in the superficial perineal pouch, between the perineal membrane (superior) and the deep perineal fascia (inferior).
Penis: root
Crura and bulb consists of
erectile tissue: corpus cavernosum & corpus spongiosum.
Penis: root
Crura attached to
ischial ramus
Penis: root
Posterior part of the bulb:
penetrated by urethra.
Penis: Body
suspended from
the pubic symphysis.
Penis: body
Has no muscles
penis body consists of
thin skin, connective tissue, blood & lymphatics, fascia, corpora, urethra.
- Skin is connected to tunica albuginea by loose connective tissue.
Penis: Glans
Is the
Distal expansion of corpus spongiosum.
Penis: Glans
Corona:
projection of glans beyond ends
of corpora cavernosa.
Separates glans from body
Neck
near the tip of the glans.
External urethral orifice/meatus
Penis: Glans
Skin and fascia form a
double layer: prepuce (foreskin)
➢Covers the glans penis.
➢Frenulum of prepuce: median fold that attaches deep layer of prepuce to the glans.
Penis: Ligaments
- Suspensory: condensation of deep fascia arising from the anterior surface of the pubic symphysis.
➢passes inferiorly and splits to form a sling that attaches to the deep fascia of the penis (at the junction of the body & root).
➢anchors erectile bodies to pubic symphysis.
➢Short and taut. - Fundiform: irregular condensation of collagen and elastic fibres of the subcutaneous tissues
➢Descends in midline from linea alba to the pubic symphysis
➢Splits to surround the penis, then reunites and blends inferiorly with dartos fascia forming the scrotal septum.
➢superficial to suspensory ligament, blends with dartos fascia forming scrotal septum.
➢Long and loose.
Penis: Arterial supply
- Penile skin: Superficial and deep branches of external pudendal artery (from femoral arteries).
- Branches of internal pudendal artery:
❑Skin & fascia of penis, corpus spongiosum,
spongy urethra: dorsal artery of penis.
➢Runs on each side of deep dorsal vein in dorsal groove between corpora cavernosa.
❑Corpora cavernosa: deep artery of penis. ➢Pierces crura & runs through center of corpus. ➢Give off cavernous arteries.
➢Involved in erection.
❑Bulb of corpus spongiosum and urethra within it & bulbourethral glands: artery of bulb of penis
Penis: Venous drainage
- Deep dorsal vein: drains blood from cavernous spaces via venous plexus that drains into prostatic venous plexus.
➢Passes between the laminae of the suspensory ligament, inferior to the inferior pubic ligament, anterior to the perineal membrane. - Superficial dorsal vein: drains blood from skin & subcutaneous tissue.
➢Drains into superficial external pudendal vein.
Penis: Innervation
- Nerves arise from S2, S3, S4, either through pelvic splanchnic or pudendal nerves.
- Skin and glans penis – dorsal nerve of penis from pudendal nerve (sensory and sympathetic), see previous slide.
➢Passes through pudendal canal & deep perineal pouch.
➢Runs lateral to deep dorsal artery on the dorsum of penis.
➢Glans has rich supply of nerve endings. - Skin of root – ilioinguinal nerve.
- Parasympathetic vasodilator nerves from pelvic splanchnic nerves supply erectile tissue via cavernous nerves (through prostatic plexus).
Penis: Lymphatic drainage
- Skin of penis drains into superficial inguinal nodes.
- Glans and distal spongy urethra drain into deep inguinal nodes.
- Cavernous bodies and proximal spongy urethra drain into internal iliac nodes.
Erection
- Stimulation.
- Parasympathetic innervation: cavernous nerves relax smooth muscle
in cavernous arteries.
➢Arteries straighten, enlarge their lumen.
➢Increases blood flow into the cavernous spaces of the corpora cavernosum. - Muscles of perineum (bulbospongiosus & ischiocavernosus) compress veins draining corpora cavernosum, preventing their drainage.
- Erectile tissues engorged with blood and become rigid.
