Pelvis And Perineum 2 Flashcards
Describe the anatomy of Testes
Two ovoid shaped organs that develop in the abdominal cavity and descend into the scrotum
Takes its blood supply and venous drainage with it
Sites of sperm production throughout the adult life starting in puberty
Located in the scrotum to allow for careful temperature regulation
Still considered internal organs since the blood supply, lymphatic drainage and innervation are all derived from the lumbar region
Describe the anatomy of the ductus deferens
Muscular tube originating from the tail of the epididymis
Passes in the spermatic cord through the inguinal canal towards the posterior aspect of the bladder
It expands to form the ampulla before joining the duct of the seminal vesicle to form the ejaculatory duct
What are the seminal vesicles?
Paired glands
posterior to bladder
Duct joins ampulla of ductus deferens to form ejaculatory duct
Produces about 60% of volume of semen
Describe the anatomy of the prostate gland
- Almond shaped gland in the prepubescent individual that gradually increase in size with age under the influence of DHT-5
- Base - at bladder neck
- Apex - at UG hiatus of pelvic diaphragm in contact with the superior fascia of the deep perineal pouch
- Posterior aspect lies in close relation to the ampulla of the rectum
- The ejaculatory ducts pass through it to drain into the urethra
Contrast the types of prostatic divisions
Anatomical lobes
These divisions are based on where the different parts can be palpated
The median lobe is anterior to the ejaculatory ducts while the posterior lobe is posterior, both these lobes are posterior to the urethra
Anatomical zones
The regions of the prostate based on the histological structure
These zones are also related to the different disease processes that may affect
Explain what is a digital rectal exam
Digital rectal exam is important for detection of prostate abnormalities. DRE in combination with Prostate Specific Antigen (PSA) will help determine the possibility of prostate cancer and benign prostatic hyperplasia
Structures that can be palpated in the male are : prostate, seminal vesicle, rectovesical pouch
Structures that can be palpated in the female are: posterior wall of vagina, cervix, rectouterine pouch (of Douglas)
What is benign prostatic hyperplasia?
- Hyperplasia of the glandular epithelium
- Transitional and periurethral zones
- Due to the location of the hyperplasia it causes urethral obstruction
- On DRE the prostate feels bulky
What is prostate cancer?
- Most commonly diagnosed cancer in men
- Peripheral zone
- Relatively asymptomatic
- On DRE the prostate feels hard like a rock
When is transurethral resection of prostate(TURP)?
Done for BPH due to location of enlarged tissue
What is the blood supply to the male perineum?
Inferior vesicle artery: bladder neck and prostate
Vesical and prostatic venous plexuses: drain mainly to iliac veins but also communicate with the external vertebral venous plexus
Communicates with the internal vertebral plexus (of Batson) valveless system
What is the significance of prostatic cancer metastasis ?
Since the prostatic plexus and the internal venous plexus of veins have a communication, cancer cells may spread via this route.
This plexus connects specifically to the venous drainage of the cranial cavity and may serve as a route for metastasis to the brain.
Summarize lymphatic drainage of the male perineum
Testes drain to lumbar nodes
Prostate, seminal vesicles, ductus deferens drain into internal iliac nodes
What is the urogenital triangle?
The crura are covered by the ischiocavernosus muscles
The bulbospongiosus muscle covers the bulb of the penis and the two sides fuse together to form a raphe
Contraction of these two muscles assist in expulsion of semen from the urethra during ejaculation
What are the roles of which external genitalia for the male?
Suspensory ligament of the penis
extends from the pubic symphysis to the the dorsal aspect of the body of the penis
Prepuce/ foreskin
surrounds the glans, is the part removed during circumcision
Bulb
covered by bulbospongiosus muscles
Scrotum
Skin and fascia that contains the testes
What is the role of the corpus cavernosum?
Crura that lie lateral to the corpus spongiosum
What is the root of the penis?
Anatomical position is erect The penis has a root consisting of
both the crura and the bulb
The crura consist of corpus cavernosum, erectile tissue with large spaces
What is the anatomy of the corpus spongioum?
The corpus spongiosum has smaller spaces and contains the urethra along its entire length
The glans is an expansion of the spongiosum into which the two corpora cavernosa fit
The ridge formed by the glans is known as the corona
What is the glans penis?
Expanded portion of the corpus spongiosum
What is the bulb of the penis?
Expanded proximal portion of corpus spongiosum
Summarize the penis internal structure
The erectile tissue remain as three distinct bodies
The erectile bodies are surrounded by a thick fibrous fascia = tunica albuginea, septa divide the cavernosum into cavernous spaces into which the helicine arteries open
The Buck’s Fascia encloses all three bodies
What is the navicular fossa?
Expanded portion of the spongy urethra
Clinically the urethra is divided into
Anterior and posterior portions
What is anterior urethral injury?
Injury to the urethra is common in straddle injuries such as; falling on a bicycle crossbar, fence or any hard surface with open legs
This will cause urine (and blood) to leak out into the surrounding tissues
Since Buck’s fascia is fibrous the injury may not tear into it
No injury to Buck’s fascia Extravasation is limited to the penis (deep to Buck’s)
With injury to Buck’s fascia Extravasation will extend into the superficial perineal pouch
What can cause a posterior urethral tear?
May be due to straddle injuries or direct trauma to the groin. Symptoms may include blood leaking from the urethral orifice and pain.
Describe the terminal portion of internal pudendal artery
Terminal portion of internal pudendal a. accompanies the dorsal nerve of the penis: supplies the deep perineal pouch and erectile tissues
Males: artery of the bulb of the penis, urethral artery, deep artery of the penis and dorsal artery of the penis
Describe autonomic innervation of male perineum
Parasympathetic fibers from the pelvic splanchnic nerves (S2-4) to the erectile tissues travel via the prostatic plexus and run to the erectile tissues as the cavernous nerves these cause dilation of helicine arteries allowing filling of blood for erection
hypogastric nerves bring sympathetic fibers
pelvic splanchnic nerves add PNS fibers
sacral splanchnic nerves add SNS fibers
Describe the nervous importance of erection
- Parasympathetic innervation by the cavernous nerves causes dilation of the arteries to the penis, clitoris and bulbs of the vestibule
- This causes the vascular spaces inside the erectile tissues to fill with blood
- Due to the resulting enlargement of the corpora cavernosa the veins are compressed preventing the blood from draining temporarily
Since erection is a vascular event prolonged erection is extremely dangerous; a condition known as priapism
Interruption of the cavernous nerves during prostatectomy leads to erectile disfunction
Describe the science behind the emission phase of the ejaculation
Emission phase:
Sympathetic innervation
promotes secretion of fluids by the glands and smooth muscle contractions of the ductus deferens and ejaculatory ducts
causing semen to accumulate in the urethral bulb = inferior hypogastric plexus
Internal urethral sphincter contracts closing the communication to the bladder
Describe the expulsion of the ejaculation phase
Expulsion phase:
Rhythmic contractions of the bulbospongiosus and ischiocavernosus muscles = pudendal nerve
• Expels semen accumulated during the emission phase through the urethra
• simultaneous sympathetic innervation causes constriction of vessels and reduces erection
