Male reproductive anatomy Flashcards
Embryologically, where are testes derived from? How do they travel to the scrotum? What do they pull with them?
Derived from intermediate mesoderm
Descend from high on the posterior abdo wall (L2) to the scrotum
Drag the neurovasculature supply and lymphatic vessels
What guides the testes down to the scrotum?
The gubernaculum and processus vaginalis help testes descend through the inguinal canal. (Same layers as ant abdo wall) - testes develop in retroperitoneal position
What is the primary function of the testes?
Site of spermatogenesis - seminiferous tubules
Where does lymph drain from the testes?
Para-aortic nodes (L2)
What is the processus vaginalis? What does the lower part form? What happens to the upper part?
Fold of parietal peritoneum, helps guide the testes down the inguinal canal
Lower part of processus vaginalis surrounds the testicle and becomes the tunica vaginalis
Upper part should seal off (obliterated)
What might a patent processus vaginalis result in? (open)
Potential weak spot - route taken by indirect hernias
What is the tunica albuginea and how does it relate to lobules and seminiferous tubules?
Tunica aluginea - tough fibrous coat (of testicle) that gives rise to septa and divides testes into lobules.
Lobules contain seminiferous tubules (site of spermatogenesis)
After sperm are produced in the seminiferous tubules, where do they go?
Move to the rete testes -> efferent ductules -> head of epididymis -> body/tail -> ductus deferens
What are the differences between spermatocele and hydrocele?
Spermatocele - swelling in epididymis (can feel boarders of testes)
Hydrocele - fluid surrounds whole testicle (can’t feel testicle)
What is the primary function of the scrotum?
Keep gonads 3-4 degrees COOLER than body temp
What are the spermatic cord layers derived from the ant abdo wall? starting from superficial
Ext oblique aponeurosis -> Ext spermatic fascia
Int oblique -> Cremasteric fascia (muscular)
Transversalis fascia -> Int spermatic fascia
What are the contents of the spermatic cord? (rule of 3) Name arteries, nerves and other structures)
Arteries:
1. TESTICULAR a. 2. Cremasteric a. 3. Ductus deferens a.
Nerves:
1. genitofemoral n. 2. Autonomic n. 3. ILIOINGUINAL n.
Other structures!:
1. Ductus deferens 2. Pampiniform plexus (veins) 3. Lymphatics
Where do the left and right testicular veins drain to? Where do the testicular arteries from?
Testicular arteries arise from the aorta
R. testicular vein drains to IVC and L. testicular vein drains to left renal veins
What are varicoceles?
Abnormal dilations of the pampiniform plexus
‘BAG OF WORMS’
More common the left
What happens in a vasectomy? and what must be watch out for?
Male sterilization
Ductus deferens is cut and ligated just distal to superficial inguinal ring
Must watch out for ilioinguinal nerve (innervation to ext genitalia and pubic area)
What is testicular torsion and why might testicular pain be a SURGICAL EMERGENCY?
Twisting of the testis upon the spermatic cord - compromise blood supply.
ALL testicular pain is TORSION unless proven otherwise
Is the smooth muscle of ductus deferens capable of peristaltic action?
Yes - with sympathetic innervation
Embryolgically, what is the ductus deferens derived from?
Embryonic mesonephric duct
Describe the seminal vesicles. Do they store sperm? What is their main function?
Paired accessory sex glands (5cm long) located posterolateral to bladder.
DO NOT store sperm
Produce alkaline fluid - contributes to ejaculate
Combine with ductus deferens to form ejaculatory ducts - open into prostatic urethra
Related posteriorly to the rectovesical pouch
What percentage of seminal fluid (ejaculate) does the prostate contribute to?
20%
How can you palpate the prostate gland?
DRE - posterior aspect is easily palpable
Where does the prostatic venous plexus drain to?
Internal iliac veins and/or vertebral plexus
What lobes/zones do benign prostatic enlargement and prostate cancer often occur?
BPH - Median lobe/transitional zone
Prostate cancer - peripheral zone
Why might prostate cancer present with back pain?
Metastatic deposits in the vertebrae via the venous plexus
What are the male parts of the urethra (starting from deep)?
Preprostatic prostatic membranous spongy navicular fossa
What are the three places of resistance during a male catheterisation?
1) Navicular fossa
2) Fixed angle - urethra bends in the root of the penis after passing through the perineal membrane
3) Prostate/internal/external urethral sphincters
What tissue forms the glans at the end of the penis?
Corpus spongiosum - expands (contains urethra)
Where are the bulboureathral/Cowper’s glands located?What can happen if they become infected?
In DPP
Can become infected/develop stones
Cause perineal pain and pain on defecation / DRE
What can happen as a result of blunt force trauma to the penile bulb (base of penis)?
Rupture the urethra resulting in extravasion of urine (or blood) into the SPP
The anatomical position of the penis is in …
erection
What is the innervation of the bulbospongiosus and ischiocavernosus muscle?
Pudendal nerve S2-4
What are the ligaments which support the base of the body of the penis?
Fundiform ligament
Suspensory ligament
What is the foreskin anchored to the glans by?
Frenulum
Why do open vascular channels allow blood to enter and engorge mainly the corpora cavernosa and not the spongiosum?
Because spongiosum contains the urethra and can collapse and stop ejaculation
What can cause the fracture of a penis?
Traumatic rupture of corpus cavernosum
What is the difference between phimosis and paraphimosis?
Phimosis - foreskin cannot be retracted over the glans (stuck around the glans)
Paraphimosis - foreskin in stick in retracted position behind the glans
What is priapism and how would you treat it?
Persistent (painful) non-stimualted erection that lasts >4 hours and unrelieved by ejaculation
Treat by draining blood from lateral side of penis with injection. Avoid the dorsal side as it has major neurovasculature
What is the primary function of the ischioanal fossae?
Fat filled wedges help to support the pelvic floor
Fat allows for rectal distension and defecation
What is fournier gangrene?
Necrotizing fasciitis of the perineal region
What does the scarpa’s fascia become when it covers the penis/scrotum and SPP?
Dartos fascia
Colle’s fascia
Where does scarpa’s fascia bind to below the inguinal ligament?
Binds to the fascia lata of thigh just below the inguinal ligament
What canal lies in lateral ischioanal fossae within fascia over the obturator internus?
Pudendal (Alcock’s) canal - main neurovascular supply to the penis and clitoris
What are the three terminal branches of the pudendal nerve?
- Inferior rectal
- Perineal
- Dorsal nerve of the penis
Where do the parasymp and symp fibres unite on the lateral pelvic wall? Where do they come from?
Inferior hypogastric plexus
Parasymp - come from pelvic splanchnic nerves
Symp - hypogastric nerves and sacral splanchnic nerves
Where do the nerves go from the inferior hypogastric plexus?
Travel medially to form plexi associated with pelvic organs (e.g. rectum and prostate)
What might happen if you damage cavernous nerves during a prostate removal?
Cavernous nerves extend from prostatic plexus and move into penis - bring about erection. If the autonomic nerves are damaged during surgery, may result in impotence
Where do the following structures drain to?
Testicles, glans of penis, distal urethra, scrotum, penile and perineal skin?
Testicles - para-aortic nodes
glans of penis, distal urethra - deep inguinal
Scrotum, penile and perineal skin - superficial inguinal
Everything else - internal iliac nodes
What is the innervation for erection, emission and ejaculation? (hint: point shoot and score)
Parasymp, Symp and Somatic
What does erection involve?
Straightening of the coiled helicine arteries which allows blood to fill the corpus cavernosum by relaxing of smooth muscle in helicine arteries.
Bulbospongiosus and ischiocavernosus muscles compress venous plexus (retain blood in penis)
What happens during emission?
Symp innervation (L1/2) brings about secretion from glands, peristalsis of ductus deferens and close of internal urethral sphincter -> seminal fluid and sperm move to bulb of penis
What happens during ejaculation?
Rhythmic contractions of somatically innervated bulbospongiosus - squeezes penile bulb and urethra
Also helps urethral emptying in male following urination
