Male reproductive system

Question 1

What is the arterial supply to the penis?

Answer 1

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

Question 2

What is the venous drainage of the penis?

Answer 2

Superficial and deep dorsal veins drain into the prostatic venous plexus and then into the IVC

[Can also drain via the vertebral plexus]

Question 3

What is the lymphatic drainage of the testicles?

Answer 3

Para-aortic nodes (L2) - not palpable

Question 4

What is the lymphatic drainage of the scrotal, penile and perineal skin?

Answer 4

Superficial inguinal nodes

Question 5

What is the lymphatic drainage of the glans of the penis?

Answer 5

Deep inguinal nodes

Question 6

What is the somatic innervation of the perineum?

Answer 6

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

Question 7

What is the clinical relevance of the location of the pudendal nerve?

Answer 7

Runs close to the ischial spine - can be used as a landmark to anaesthetise perineal region, penis and sphincters

Question 8

What is the somatic innervation of the penis?

Answer 8

Dorsal nerve of penis (pudendal nerve branch)

Question 9

What is the autonomic innervation of the penis?

Answer 9

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

Question 10

Where is the superior hypogastric plexus found?

Answer 10

Approx. L4 before splitting into two branches

Contains sympathetic and parasympathetic fibres

Question 11

What is the clinical relevance of nerve plexi found in the pelvic region?

Answer 11

Close relation to pelvic organs increases likelihood of damage during surgery

Question 12

What main parts of the nervous system are associated with erection, emission and ejaculation?

Answer 12

Erection = parasympathetic 
Emission = sympathetic
Ejaculation = somatic 

[Point, Secrete, Score]

Question 13

What is required for erection to occur?

Answer 13

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

Question 14

What vascular structures allow penis to remain flaccid majority of the time?

Answer 14

Arteriovenous anastamoses allowing blood to bypass the corpora cavernosa

Question 15

What is emission and how is this brought about?

Answer 15

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

Question 16

What is the importance of the internal urethral sphincter during emission and ejaculation?

Answer 16

Closes to prevent retrograde ejaculation into the urinary bladder

Question 17

What causes ejaculation?

Answer 17

Somatic innervation (Pudendal n.) resulting in rhythmic contractions of the bulbospongiosus, squeezing the penile bulb and urethra

Question 18

Where are the testes derived form?

Answer 18

Intermediate mesoderm on posterior abdominal wall

Question 19

How do the testes regulate temperature?

Answer 19

Dartos muscle - contracts in cool environments to pull testes towards body and relaxes in hot environments

Question 20

What is the contents of the spermatic cord?

Answer 20

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

Question 21

What are the coverings of the spermatic cord from superficial to deep (and where are they derived from)?

Answer 21

1. External spermatic fascia (from external oblique aponeurosis)
2. Cremasteric fascia (from internal oblique muscle)
3. Internal spermatic fascia (from transversalis fascia)

Question 22

Where can testicular pain refer to?

Answer 22

Abdomen

Question 23

How is the vasculature of the testes arranged in the spermatic cord?

Answer 23

Pampiniform (venous) plexus wrapped around the testicular artery - allows for counter-current heat exchange

Question 24

Where is the Ductus (Vans) Deferens derived from?

Answer 24

Mesonephric ducts

Question 25

What forms the ejaculatory duct?

Answer 25

Ampulla of the Vas Deferens

Seminal vesicles

Question 26

Which zone is most commonly affected in prostate cancer?

Answer 26

Peripheral

Question 27

Which zone is most commonly affected in BPH?

Answer 27

Transitional

Question 28

What are the possible routes of venous drainage from the prostate and what is its clinical relevance?

Answer 28

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

Question 29

What ligaments support the body of the penis?

Answer 29

Suspensory and fundiform ligaments

Question 30

What muscles cover the crura and bulb of the penis and what is their nerve innervation?

Answer 30

Ischiocavernosus and Bulbospongiosus

Somatic - Pudendal (S2-4)

Question 31

What is phimosis?

Answer 31

Condition where foreskin cannot be retracted over the glans

Question 32

What is paraphimosis?

Answer 32

Condition where the foreskin is stuck in a retracted position behind the glans

Question 33

What is priapism?

Answer 33

Persistent, painful, non-stimulated erection lasting over 4 hours and unrelieved by ejaculation
Requires prompt treatment

Question 34

What is the ischioanal fossae?

Answer 34

Fat filled spaces below the pelvic floor that communicate across the midline - helps to support the pelvic floor

Question 35

What is the superficial fascia in the perineal region and what is the clinical relevance of this?

Answer 35

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