Part 18: Male Urogenital Region

Question 1

What is the perineal membrane?

Answer 1

unyielding sheet of fibrous tissue attached to both ischiopubic rami from just behind subpubic angle to just anterior to ischial tuberosities. Anteriorly forms transverse perineal ligament. Posteriorly attached to superficial perineal fascia which fuses with perineal body

Question 2

What is the deep perineal pouch?

Answer 2

Space between perineal membrane (deep) and the loose pelvic fascia above urogenital diaphragm (superior fascia of UG diaphragm)

Question 3

What is the urogenital diaphragm?

Answer 3

Muscle mass superior (deep) to perineal membrane.

Consists of sphincter urethrae (external urethral sphincter) and paired deep transverse perineal muscles.

Question 4

Where are the bulbourethral glands (of Cowper) located?

Answer 4

Each side of membranous urethra in deep perineal pouch. Ducts pierce perineal membrane to open into penile urethra. Contribute small amount to seminal fluid.

Question 5

What is the superficial perineal pouch?

Answer 5

Area between superficial perineal fascia (of Colles) and perineal membrane.

Question 6

What are the margins of Colles fascia?

Answer 6

Front - pubic bone - continues up into AAW as scarpa’s fascia.
Projected into scrotal and penile expansions.
Therefore theoretically ruptures penile urethra - urine could extent all the way up AAW

Question 7

How is the penis attached to the pelvis?

Answer 7

Root of penis attached to perineal membrane, consisting of central bulb and lateral crus

Question 8

What are the main constituents of the penis?

Answer 8

Lateral crus: Corpus cavernosum (bound side by side), suspended from the PS via the suspensory ligament.
Central bulb: Corpus spongiosum, accepts urethra, arteries and ducts of bulbourethral glands

Question 9

What is the surrounding fascia of the penis?

Answer 9

Tunica albuginea surround each corpus. This is surrounded by Buck’s fascia (continuation of scarpa’s fascia)

Question 10

Within Buck’s fascia lie what vessels and nerves?

Answer 10

Dorsal arteries and Dorsal nerves
Dorsal Vein
Superficial to Bucks fascia is superficial dorsal vein and lymphatics

Question 11

What is the blood supply to the penis?

Answer 11

3 pairs of arteries - all branches from internal pudendal

• branch to bulb (supplies CS and glands)
• dorsal arteries supply skin, fascia, glans - anastomoses with bulb artery
• Deep artery supplies CC - closed system which is essential to erection

Question 12

What is the venous drainage of penis?

Answer 12

Mainly though deep dorsal vein, other small veins pass with arteries. Passes above perineal membrane (anterior to transverse perineal ligament) to vesicoprostatic plexus

Question 13

What is lymphatic drainage of penis?

Answer 13

Skin - to superfical inguinal nodes

CS + CC - to deep inguinal nodes

Question 14

What is the nerve supply of penis?

Answer 14

Pudendal nerves via posterior scrotal and dorsal nerves (mainly S2)
Sympathetic nerves essential for ejaculation are derived from L1 of spinal cord via superior and inferior hypogastric plexus
Pelvic splanchnic supplies PSNS supply to all corpora to allow increased blood flow for erection

Question 15

What are the superficial perineal muscles?

Answer 15

Bulbospongiosus (AKA compressor urethrae - from perineal body/midline raphe forwards and laterally over bulb to perineal membrane - helps empty urethra
Ischiocavernosus - posterior part perineal membrane/ramus ischium to upper surfaee of CC - supports erect penis
Superficial transverse perineal muscle - perineal membrane to perineal body(helps stabilise body)

Question 16

How long is the male urethra? What are its parts and lengths?

Answer 16

20cm
Prostatic: 5cm
Membranous: 1.5cm
Spongy/penile: 15cm

Question 17

Where does the urethra take 90’ turn?

Answer 17

From perineal membrane to bulb

Question 18

What is the navicular fossa?

Answer 18

Just proximal to external urethral meatus. Short dilated region of urethra. Lining is stratified squamous epithelium as opposed to transitional epithelium.

Question 19

Where is the narrowest parts of urethra?

Answer 19

Bladder neck, membranous part and just proximal to navicular fossa

Question 20

What is the blood supply to the urethra?

Answer 20

Multiple sources given its length. No one artery to urethra

Question 21

Describe dartos muscle of scrotum?

Answer 21

There’s no subcut tissue fat in scrotum. Dartos is part of panniculus carnosus - sends sheet to midline fibrous septum of scrotum. Smooth muscle supplied by sympathetic branches (likely genital branch of genitofemoral)

Question 22

What are the branches of the internal pudendal artery?

Answer 22

Inferior rectal artery
Perineal branch
Posterior scrotal branch
Transverse perineal branches
Artery to bulb
Dorsal penile branches
Deep branch to CC