Male reproductive system Flashcards
What is the arterial supply to the penis?
Internal pudendal artery (a branch of the internal iliac artery)
Leaves pelvic cavity through greater sciatic foramen and into the perineal region through lesser sciatic foramen before travelling through the pudendal (Alcock’s) canal (a thickening of fascia over the Obturator Internus) giving off branches to the rectum and perineum en route
What is the venous drainage of the penis?
Superficial and deep dorsal veins drain into the prostatic venous plexus and then into the IVC
[Can also drain via the vertebral plexus]
What is the lymphatic drainage of the testicles?
Para-aortic nodes (L2) - not palpable
What is the lymphatic drainage of the scrotal, penile and perineal skin?
Superficial inguinal nodes
What is the lymphatic drainage of the glans of the penis?
Deep inguinal nodes
What is the somatic innervation of the perineum?
Pudendal nerve (S2-S4) - passes out of pelvic cavity via greater sciatic foramen and into perineal region via the lesser sciatic foramen and runs through pudendal canal with the pudendal artery
What is the clinical relevance of the location of the pudendal nerve?
Runs close to the ischial spine - can be used as a landmark to anaesthetise perineal region, penis and sphincters
What is the somatic innervation of the penis?
Dorsal nerve of penis (pudendal nerve branch)
What is the autonomic innervation of the penis?
Parasympathetic = pelvic splanchnic nerve (S2-S4) - important for erection Sympathetic = hypogastric nerve and sacral splanchnic nerves
Parasympathetic and sympathetic fibres unite to form inferior hypogastric plexus on the lateral pelvic wall and then travel medially to form plexi associated with pelvic organs (e.g. rectal plexus and prostatic plexus)
Cavernous nerves from the prostatic plexus extend to penis
Where is the superior hypogastric plexus found?
Approx. L4 before splitting into two branches
Contains sympathetic and parasympathetic fibres
What is the clinical relevance of nerve plexi found in the pelvic region?
Close relation to pelvic organs increases likelihood of damage during surgery
What main parts of the nervous system are associated with erection, emission and ejaculation?
Erection = parasympathetic Emission = sympathetic Ejaculation = somatic
[Point, Secrete, Score]
What is required for erection to occur?
Filling of vascular channels within corpora cavernosa to increase pressure inside resulting in swelling which makes penis rigid
Helicine arteries regulate blood flow into the corpora cavernosa - normally coiled to minimise blood flow into corpora cavernosa - relaxation of smooth muscles in these arteries (parasympathetic mediation by nitric oxide) straightens out arteries and increases blood flow.
Compression of the venous plexus by ischiocavernosus and bulbospongiosus (somatically innervated muscles) prevents blood draining from the penis
What vascular structures allow penis to remain flaccid majority of the time?
Arteriovenous anastamoses allowing blood to bypass the corpora cavernosa
What is emission and how is this brought about?
Seminal fluid and spermatozoa moved to bulb of penis
Secretion from glands, peristalsis of ductus deferens and closure of internal urethral sphincter brought about by sympathetic innervation from L1/L2
What is the importance of the internal urethral sphincter during emission and ejaculation?
Closes to prevent retrograde ejaculation into the urinary bladder
What causes ejaculation?
Somatic innervation (Pudendal n.) resulting in rhythmic contractions of the bulbospongiosus, squeezing the penile bulb and urethra
Where are the testes derived form?
Intermediate mesoderm on posterior abdominal wall
How do the testes regulate temperature?
Dartos muscle - contracts in cool environments to pull testes towards body and relaxes in hot environments
What is the contents of the spermatic cord?
3 arteries: testicular, cremasteric and ductus deferens
3 nerves: genital branch of genitofemoral, autonomic nerves and ilioinguinal
3 other structures: ductus (vans) deferens, pampiniform plexus and lymphatics
What are the coverings of the spermatic cord from superficial to deep (and where are they derived from)?
- External spermatic fascia (from external oblique aponeurosis)
- Cremasteric fascia (from internal oblique muscle)
- Internal spermatic fascia (from transversalis fascia)
Where can testicular pain refer to?
Abdomen
How is the vasculature of the testes arranged in the spermatic cord?
Pampiniform (venous) plexus wrapped around the testicular artery - allows for counter-current heat exchange
Where is the Ductus (Vans) Deferens derived from?
Mesonephric ducts
What forms the ejaculatory duct?
Ampulla of the Vas Deferens
Seminal vesicles
Which zone is most commonly affected in prostate cancer?
Peripheral
Which zone is most commonly affected in BPH?
Transitional
What are the possible routes of venous drainage from the prostate and what is its clinical relevance?
Prostatic plexus drains into Internal Iliac veins and then IVC
Can also pass to valveless vertebral venous plexus allowing metastatic cancer spread up the spine
What ligaments support the body of the penis?
Suspensory and fundiform ligaments
What muscles cover the crura and bulb of the penis and what is their nerve innervation?
Ischiocavernosus and Bulbospongiosus
Somatic - Pudendal (S2-4)
What is phimosis?
Condition where foreskin cannot be retracted over the glans
What is paraphimosis?
Condition where the foreskin is stuck in a retracted position behind the glans
What is priapism?
Persistent, painful, non-stimulated erection lasting over 4 hours and unrelieved by ejaculation
Requires prompt treatment
What is the ischioanal fossae?
Fat filled spaces below the pelvic floor that communicate across the midline - helps to support the pelvic floor
What is the superficial fascia in the perineal region and what is the clinical relevance of this?
Camper’s fascia layer becomes Dartos muscle in the scrotum
Scarpa’s fascia continues into penis and scrotum as Dartos fascia which then becomes Colles’ fascia in the urogenital triangle
Clinical relevance = infection can track up anterior abdominal wall as Scarpa’s fascia binds to fascia lata of thigh preventing infection from spreading down legs
