Blood Supply, Penis and Scrotum

BLOOD SUPPLY Penile skin

Blood is supplied to the skin of the penis by: superficial external pudendal vessels
– Origin: arise from the first portion of the femoral artery
– Course: cross the upper medial portion of the femoral triangle, and divide into two main branches, running dorsolaterally and ventrolaterally in the shaft of the penis with collateralization
across the midline.
– At intervals, they give off fine branches to the skin, forming a rich subdermal vascular plexus that can sustain the skin after its underlying dartos fascia has been mobilized.
– The arteries are accompanied by venous tributaries that are more prominent and easily seen than the arteries.

Because of its remarkable thinness and mobility and the character of its vascular supply, the skin covering the penis is an ideal substitute, in some cases, for urethral reconstruction.
– A flap of skin can be elevated and the fascia containing its blood supply can be mobilized to construct a subcutaneous pedicle, allowing distal islands of preputial or penile skin to be transferred to virtually any part of the urethra.

NOTE: The blood supply to the scrotal wall and ventral penile skin is based on the posterior scrotal artery, a superficial vessel from the deep internal pudendal artery. As with the superficial external pudendal tributaries, the posterior scrotal system provides a series of tributaries carried within the tunica dartos.

BLOOD SUPPLY penis arterial system

internal pudendal artery –> penile arteries –> paired dorsal arteries
(lateral to deep dorsal vein and medial to dorsal penile nerve: N A V A N)

common penile artery continues in Alcock’s canal, above the perineal membrane, and terminates in three branches to supply the erectile bodies.
– bulbourethral artery penetrates the perineal membrane to enter the spongiosum from above at its posterolateral border. This large, short artery can be difficult to isolate and control during urethrectomy. It supplies the urethra, spongiosum, and glans.
– cavernosal artery pierces the corporal body in the penile hilum to near the center of its erectile tissue. It gives off straight and helicine arteries that ramify to supply the cavernous sinuses.
– dorsal artery of the penis passes between the crus penis and the pubis to reach the dorsal surface of the corporal bodies. It runs between the dorsal vein and the dorsal penile nerve and with them attaches to the underside of Buck’s fascia. As it courses to the glans, it gives off cavernous branches and circumferential branches to the spongiosum and urethra. The rich blood supply to the spongiosum allows safe division of the urethra during stricture repair

BLOOD SUPPLY Penis Venous system

The penis is drained by three venous systems: superficial, intermediate, and deep.
SUPERFICIAL veins:
–  contained in the dartos fascia on the dorsolateral aspects of the penis unite at its base to form a single superficial dorsal vein.
– superficial dorsal vein usually drains into the left saphenous vein, rarely into the right, and occasionally forms two trunks that drain into both.
– Veins from more superficial tissue may drain into the external superficial pudendal veins.
INTERMEDIATE system contains the deep dorsal and circumflex veins, lying within and beneath Buck’s fascia:
– Emissary veins begin within the erectile space of the corpora cavernosa and, following a perpendicular or oblique course through the tunica albuginea, emerge from the lateral and dorsal surfaces of the corpora cavernosa to empty into the circumflex veins or the deep dorsal vein.
Circumflex veins:
– are channels, usually more prominently present in the distal two thirds of the penile shaft.
– They arise from the corpus spongiosum, on the ventrum of the penis, and often receive the emissary veins as they travel around the lateral aspect of the corpora cavernosa, passing beneath the dorsal arteries and nerves to empty into the deep dorsal vein.
– They communicate with one another and those of the opposite side to form 3 to 12 common venous channels, usually accompanied by branches of the dorsal nerve and artery.
– The circumflex veins can also become confluent ventrally, forming periurethral veins on each side; these may become important in the treatment of impotence caused by veno-occlusive incompetence.

Deep dorsal vein:
– formed by five to eight small veins emerging from the glans penis to form the retrocoronal plexus, which drains into the deep dorsal vein lying in the midline groove between the corporal bodies.
– In a number of patients, there is a connection between the superficial and deep dorsal veins. In the shaft of the penis, the deep dorsal vein often consists of two and sometimes three tributaries that anastomose with each other. The vein gathers blood from the emissary and circumflex veins, and passing beneath the pubis at the level of the suspensory ligament, it leaves the shaft of the penis at the crus and drains into the periprostatic plexus.

DEEP drainage system consists of the crural and cavernosal veins.
Crural veins:
– arise in the midline, in the space between the crura.
– Normally, they are small and almost indiscernible, joining the deep dorsal vein or the periprostatic plexus.
– If the deep dorsal vein has been ligated or obliterated after trauma, striking development of these veins can be noted as the intracrural space is entered during the perineal dissection for urethral repair.
Cavernosal veins:
– Emissary veins in the proximal third of the crura, near their attachment to the ischial tuberosities, join to form several thin-walled trunks on the dorsomedial surface of each corpus cavernosum.
– Some pass medially, joining the dorsal or crural veins, or extend proximally, entering the periprostatic plexus. Most consolidate into one or two cavernosal veins on each side.
– Running in the penile hilum, deep and medial to the cavernosal arteries and nerves, they join to form a large venous channel that drains into the internal pudendal vein.
– Three or four small cavernosal veins emerge from the dorsolateral surface of each crus and course laterally between the bulbospongiosus and the crus of the penis for 2 to 3 cm before draining into the internal pudendal veins.
– These usually insignificant vessels become larger, and can be noted more readily, in patients with veno-occlusive erectile dysfunction.
– The internal pudendal veins (usually two) run together with the internal pudendal artery and nerve in Alcock’s canal to empty into the internal iliac vein.

 

SCROTUM: Arterial Supply

The external pudendal arteries supply the anterior aspect of the scrotum.
– The internal pudendal arteries supply its posterior aspect.
– It also receives branches from the testicular and cremasteric arteries.

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