Male Reproductive System 2

Question 1

Describe the important features of the penis

Answer 1

• superficial dartos fascia which surrounds penis
• the skin doubles back on itself to form the foreskin which is continuous with the glans at corona
• secretions of sebaceous glands in foreskin form smegma
• ventral midline penile raphe

Question 2

What is balanitis and phimosis?

Answer 2

• balanitis: inflammation of the glans

- phimosis: prepuce that is too tight to retract

Question 3

Elaborate on the bodies of the penis

Answer 3

• corpus spongiosum: transmits urethra and forms the glans as a cap over the cavernous bodies
• corpora cavernosa: forms the crura and attaches the ischiopubic ramus

Question 4

Describe what you would see in a cross-section of a penis?

Answer 4

• copora cavernosa divided by a complete septum proximally and a pectiniform septum distally
• surrounded by tunica albuginea
• corpus spongiosum
• all surrounded by Buck’s fascia (deep fascia)

Question 5

describe the veno-occlusive mechanism

Answer 5

• during erection the veins deep to Buck’s fascia and in tunica albuginea are compressed
• reduces venous drainage

Question 6

Describe the muscles of the root of the penis

Answer 6

• ischiocavernosus: overlies cavernosa and surrounds each root
• bulbospongiosus: surrounds bulb of penis, compresses urethra during ejaculation, and when urinating

Question 7

What are the supportive ligaments of the penis?

Answer 7

• fundiform ligaments

- suspensory ligaments

Question 8

Describe the 4 parts of the urethra

Answer 8

• pre-prostatic: in bladder neck surrounded by internal urethral sphincter
• prostatic: where ejaculatory duct opens
• membranous: in deep perineal pouch surrounded by external urethral sphincter
• spongy: in bulb of penis, spongy body

Question 9

Expand on the membranous part of the urethra

Answer 9

• within striated external urethral sphincter (slow twitch) and pubourethral part (mixed, slow and fast twitch) of levator ani (resists surges of raised intra-abdominal pressure)

Question 10

Describe the location and function of the bulbo-urethral glands

Answer 10

• located in deep perineal pouch
• surrounded by transverse fibres of external urethral sphincter muscle
• drains into spongy urethra
• secretes mucus before ejaculation and neutralises pH of urethra as well as lubricating it

Question 11

What are the curvatures of the urethra and its clinical significance?

Answer 11

• infrapunic curvature: between membranous and bulbar urethra
• pre-pubic: in spongy urethra
• curvatures must be straightened when passing a catheter

Question 12

What is the lymph drainage of the urethra?

Answer 12

internal iliac

Question 13

Describe the nerve supply of the urethra

Answer 13

• external urethral sphincter: pudendal nerve (S2-4) and perineal branches

ANS:

• sympathetics: L1-2 superior hypogastric plexus to pelvic plexus
• parasympathetics: S2-4 pelvic splanchnic neres to pelvic plexus
• visceral afferents: sacral parasympathetics S2-4
• somatic afferents: pudendal nerve S2-4 and perineal branches

Question 14

Describe how an erection occurs

Answer 14

• parasympathetic input promotes NO release from endothelium
• vasodilation and engorgement of erectile bodies
• veno-occlusive mechanism and contraction of muscles in root of penis facilitate erection

Question 15

Describe how ejaculation occurs

Answer 15

• smooth muscle contraction and rhythmic contraction of bulbospongiosus
• sympathetic input leads to contraction of smooth muscle and arterial vasoconstriction (reducing inflow of blood and veno-occlusive mechanism)