Anatomy: normal and erectile dysfunction Flashcards
Erection caused by
Parasympathetic (point)
Ejaculation caused by
sympathetic (shoot)
Function of spongiosum
As cavernosa expand, spongiosum prevents urethra being flattened
Blood supply to penis
- Internal pudendal arteries (from internal iliac arteries)
- Pudendal artery and nerve go through Allcock’s canal
- Internal pudendal = erectile tissue
- External pudendal = tissue surrounding
Venous drainage of penis
Venous plexus of pelvis
Which testicle drain to IVC?
Right
Which testicle drains to renal vein?
Left
Contents of Alcock’s canal
Pudendal nerve
Internal pudendal vein
Internal pudendal artery
Penis innervation
- 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
Path of semen during ejaculation
- 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
How does normal erection occur?
- 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
How does normal ejaculation occur
- 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
TURP consequence
Retrograde ejaculation
Normal remission
- Increases sympathetic stimulation and inhibits parasympathetic = constrction of smooth muscle in penile arteries
- Relaxation of bulbospongiosus and ischiocavernosus allows venous drainage of penis
What is erectile dysfunction ?
- Inability to maintain/achieve an erection
- Antihypertensives = ED
Leriche’s syndrome
Blocked internal iliaic arteries = buttock claudication and. impotence
How does viagra work?
sildenafil = originally anti-hypertensive - retains NO for more dilatation → s/e is cardiovascular disease
What is priapism?
Unwanted painful erection
Priapism treatment
- 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
Indications for circumcision
- 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
Hypospadias
Urethral meatus anywhere from perineum to end of penis
