Anatomy: normal and erectile dysfunction

Question 1

Erection caused by

Answer 1

Parasympathetic (point)

Question 2

Ejaculation caused by

Answer 2

sympathetic (shoot)

Question 3

Function of spongiosum

Answer 3

As cavernosa expand, spongiosum prevents urethra being flattened

Question 4

Blood supply to penis

Answer 4

• Internal pudendal arteries (from internal iliac arteries)
• Pudendal artery and nerve go through Allcock’s canal
• Internal pudendal = erectile tissue
• External pudendal = tissue surrounding

Question 5

Venous drainage of penis

Answer 5

Venous plexus of pelvis

Question 6

Which testicle drain to IVC?

Answer 6

Right

Question 7

Which testicle drains to renal vein?

Answer 7

Left

Question 8

Contents of Alcock’s canal

Answer 8

Pudendal nerve
Internal pudendal vein
Internal pudendal artery

Question 9

Penis innervation

Answer 9

• Somatic (conscious innervation) = pudendal which travels through Allcocks canal
• Parasympathetic: pelvic splanchnic s2-4 - from inferior hypogastric plexus to prostatic plexus
• Sympathetic T12-L2
• Pudendal supplies skin and bulbospongiosus which contracts to cause ejaculation

Question 10

Path of semen during ejaculation

Answer 10

• Sperm from epididymis, through vas deferens and out ejaculatory duct (where it combines with seminal fluid and prostatic secretions)
• Erection - ejaculation (emission and expulsion) and remission

Question 11

How does normal erection occur?

Answer 11

• Erotic stimulus stimulates parasympathetic system
• S-4 act on smooth muscle lining the cavernosal arteries of corpora cavernosa = release of NO, causing vasodilation
• Venous outflow reuced because corpora cavernosa becomes against tunica albuginea, which compresses venous plexuses and the bulbospongiosus and ischiocavernosus muscle compresses vein
• Spongiosum allows urethra to stay open

Question 12

How does normal ejaculation occur

Answer 12

• Emission: mixing of spermatozoa with seminal fluid to make semen - due to noradrenaline release contracting ductus deferens, seminal vesicles and prostate
• Expulsion: expulsion of semen as bulbospongiosus and ischiocavernosus contract
• Sympathetic fibres contract epididymis and vas deferens to push along duct, seminal vessels to move seminal fluid into common ejaculatory duct and contraction of urethral sphincter stops semen entering bladder
• Pudendal nerve = rhythmic contraction of bulbospongiosus to eject semen

Question 13

TURP consequence

Answer 13

Retrograde ejaculation

Question 14

Normal remission

Answer 14

• Increases sympathetic stimulation and inhibits parasympathetic = constrction of smooth muscle in penile arteries
• Relaxation of bulbospongiosus and ischiocavernosus allows venous drainage of penis

Question 15

What is erectile dysfunction ?

Answer 15

• Inability to maintain/achieve an erection

- Antihypertensives = ED

Question 16

Leriche’s syndrome

Answer 16

Blocked internal iliaic arteries = buttock claudication and. impotence

Question 17

How does viagra work?

Answer 17

sildenafil = originally anti-hypertensive - retains NO for more dilatation → s/e is cardiovascular disease

Question 18

What is priapism?

Answer 18

Unwanted painful erection

Question 19

Priapism treatment

Answer 19

• Ischaemic = veno-occlusion - iatrogenic, haematological disease (sickle cell anaemia) or pelvic malignancy → painful, rigid erection
• Non-ischaemic = unregulated arterial flow, semi-rigid and painless erection - follows trauma to penis, perineum or spinal cord
• Corporeal blood gas for assessment
• Venflon into penis to drain, or use saphenous vein/tube to drain to another vein
• Vigorous exercise can help too

Question 20

Indications for circumcision

Answer 20

• Phimosis - foreskin won’t contract
• Paraphimosis - foreskin is retracted but stays contracted
• Recurrent balanitis = infection
• Lesions of prepuce
• Normal not to retract foreskin until 16
• Balanitis xerotica obliterans = scarring of foreskin so can’t retract

Question 21

Hypospadias

Answer 21

Urethral meatus anywhere from perineum to end of penis