With the penis on stretch in a standing position, the superior surface of the penis is known as the dorsum and the inferior surface, is known as the ventrum
The shaft of the penis and the base of the glans are separated by the corona
Layers surrounding the corpora cavernosa, from superficial to deep (5):
Skin
Dartos (continuous with Scarpa’s and Colle’s fasciae)
Tela subfascialis (very thin connective tissue layer)
The erectile bodies; comprised of 2 spongy, paired cylinders
Contained in the tunica albuginea
The erectile tissues of the normal corpora cavernosa are separated from the tunica by the space of Smith
Proximal ends, the crura, originate at the undersurface of the puboischial rami as separate structures but merge under the pubis to form the body of the penis and remain attached up to the glans
A septum separates the corpora cavernosa but is permeable distally to allow for free communication between their vascular spaces
Each corpus cavernosum is a conglomeration of sinusoids, larger in the center and smaller in the periphery.
In the flaccid state, the blood slowly diffuses from the central to the peripheral sinusoids, and the blood gas levels are similar to those of venous blood.
During erection, the rapid entry of arterial blood to both the central and the peripheral sinusoids changes the intracavernous blood gas levels to those of arterial blood
Tough connective tissue layer composed primarily of type I collagen
A bilayered structure (inner circular, outer longitudinal) with multiple sublayers.
Outer longitudinal layer
Completely absent on the ventral groove between the 5 and 7 o'clock positions.
The most vulnerable area in the tunica albuginea
Most prostheses tend to extrude here
The lack of tunica albuginea on the ventral groove may contribute to greater ease of dorsal buckling and explain why most PD patients exhibit dorsal curvature
60-70% of plaques are located on the dorsal aspect of the penis and are usually associated with the septum
Covers the corpora cavernosa and *spongiosum
*The corpus spongiosum lacks an outer longitudinal layer or intracorporeal struts, ensuring a low-pressure structure during erections
The internal pudendal artery, (derived from the anterior branch of the internal iliac) gives off the perineal branch and posterior scrotal arteries before continuing on to become the common penile artery.
The common penile artery has 3 paired branches: CBD
Cavernosal artery
Penetrates the corpus cavernosum in the penile hilum to nearly the center of the erectile tissue
Provides straight and helicine arteries that supply the cavernous sinuses; the helicine arteries supply the trabecular erectile tissue and the sinusoids. These helicine arteries are contracted and tortuous in the flaccid state and become dilated and straight during erection
Effects tumescence of the corpus cavernosum
Bulbourethral artery
Supplies the corpus spongiosum, urethra, and glans
Penetrates the perineal membrane where it enters the corpus spongiosum from above at its posterolateral border
Dorsal artery
Supplies the dorsal surfaces of the corporeal bodiesand circumferential branches to the urethra and the corpus spongiosum; responsible for engorgement of the glans during erection; supplies distal shaft skin
Travels between the crus and the pubis then between the dorsal vein and the dorsal penile nerve, all of which attach to the underside of Buck fascia, then travels distally toward the glans
Distally, these arteries join to form a vascular ring near the glans.
Can be a great deal of variability in penile arteries.
The bulbourethral[“and urethral”?]arteries are situated outside the tunica albuginea of the corpus spongiosum on the lateral and dorsal sides
The cavernous artery and branches of the dorsal artery that supply the corpus cavernosae are surrounded by a periarterial soft-tissue sheath, which protects the arteries from occlusion by the tunica albuginea during erection
Accessory penile arteries
Exist in many instances
May constitute the dominant or only arterial supply to the corpus cavernosum in some males.
Accessory pudendal arteries arise most commonly from the obturator artery.
Superficial arterial system:
Branches from the external pudendal (originates from femoral artery) artery supply the penile skin; these vessels run in the dartos fascia layer.
The blood supply of the skin is independent of the erectile bodies. The rich anastomotic network makes penile skin ideal for mobilization on a vascular pedicle
Drainage from the 3 corpora originates in tiny venules leading from the peripheral sinusoids immediately beneath the tunica albuginea. These venules travel in the trabeculae between the tunica and the peripheral sinusoids to form the subtunical venous plexus before exiting as the emissary veins
Deep dorsal vein
Main venous drainage of the glans penis and distal two thirds of the corpora cavernosa
Usually a single vein, but sometimes more than one deep dorsal vein exists
Beneath Buck fascia and runs between the paired dorsal arteries (see above)
Travels between the corporal bodies and runs upward behind the symphysis pubis, between the inferior pubic arch and the striated urinary sphincter, to join the periprostatic venous plexus
Trifurcates into
Central superficial branch
Pierces endopelvic fascia between puboprostatics
Drains retropubic fat, anterior bladder and anterior prostate
Outside prostatic fascia
Drains into the internal pudendal vein
2 lateral plexuses
Sweep on lateral surface of prostate
Drain prostate and rectum; these then communicate with vesical plexuses on lower part of bladder
3-5 inferior vesical veins emerge from these lateral vesical plexuses and drain into the internal iliac vein
In females, the dorsal clitoral vein bifurcates to empty into lateral vaginal plexuses; these connect with vesical, uterine, ovarian, and rectal plexuses to drain into the internal iliac vein
Connections exist between pelvic plexuses and emissary veins of pelvic bones and vertebral plexuses; proposed route for dissemination of pelvic processes to pelvic & axial bone
The veins of the three systems communicate variably with each other.
Arises in the Alcock canal as the first branch of the pudendal nerve (S2-4)
Runs over the surface of the obturator internus under the levator, runs deep to the urogenital diaphragm, and passes through the deep transverse perineal muscle to run along the dorsum of the penis accompanied by the dorsal vein and dorsal artery.
Supplies sensory innervation to the glans
Small branches of the perineal nerve supply the ventrum of the penis as distally as the glans
The skin of the penis is innervated by branches of the genitofemoral nerve
Arise from the pelvic plexusfrom the lateral surface of the rectum
Run posterolateral to the apex, mid-portion and base of the prostate anterior to Denonvilliers’ fascia between the posterolateral surface of the prostate and the rectum to lie between the lateral pelvic fascia and the prostatic fascia. The branches from the cavernous nerve accompany the branches of the prostatovesicular arteryand provide a macroscopic landmark for nerve-sparing radical prostatectomy i.e. neurovascular bundle.
Innervates the corpus cavernosum and penile urethra
