Blood Supply of Perineum
The internal pudendal artery, after emerging
from the Alcock canal, gives off several branches. One, the perineal artery,
passes beneath the Colles fascia in the perineum to course forward anteriorly,
either under or over the superficial transverse perineal muscle. This vessel
supplies the superficial structures of the urogenital diaphragm and sends a
small branch, usually transversely, across the perineum (transverse perineal
artery) that anastomoses with the artery from the opposite side. The perineal
artery then continues anteriorly underneath the pubic arch and supplies both
the ischiocavernosus and bulbospongiosus muscles. It also sends branches to the
posterior scrotal surface.
The deep
terminal branch of the internal pudendal artery pierces the inferior layers of
the urogenital diaphragm and continues forward in the cleft between the
ischiocavernosus and bulbospongiosus muscles, where it divides into the dorsal
artery and the cavernous artery of the penis. As it courses between the
inferior and superior layers of the fasciae of the urogenital diaphragm, it
supplies the bulbous portion of the urethra and the corpus spongiosum. Distal
to the bulbar urethra, a small branch passes downward through the inferior
fascial layer of the urogenital diaphragm and enters the corpus spongiosum,
where it continues to the glans penis (urethral artery).
The deep
or cavernous artery of the penis pierces the inferior layer of the urogenital
diaphragm, enters the crus penis obliquely on each side, and continues distally
in the center of the corpus cavernosum of the penis. The blood flow within this
artery is commonly measured by ultrasound in the evaluation of arterial
erectile dysfunction. The dorsal artery of the penis pierces the inferior
fascia of the urogenital diaphragm, just below the transverse ligament of the
pelvis (see Plate 2-5), after which it traverses the suspensory ligament of the
penis and courses forward on the dorsum of the penis beneath Buck fascia, where
it terminates in the prepuce and glans penis. The paired dorsal arteries of the
penis are situated between a single deep dorsal vein and paired dorsal nerves.
The dorsal artery sends branches downward through the tunica albuginea of the penis
into the corpus cavernosum, where they anastomose with the ramifications of the
cavernous artery.
In
general, the arteries supplying the internal and external genitalia are
accompanied by similarly named veins. The dorsal veins of the penis, however,
pursue a different course. The subcutaneous dorsal (median and lateral) veins, which
receive tributaries from preputial veins, pass proximal to the symphysis pubis,
where they terminate in the superficial external pudendal veins that drain into
the femoral veins. The single deep dorsal vein of the penis originates in the
sulcus behind the glans penis and drains the glans and the corpus spongiosum.
It courses posteriorly in a sulcus between the right and left corpora and
passes between both of the two layers of the suspensory ligament at the penile
base (see Plate 2-6). It
then passes through an aperture between the arcuate ligament of the pubis and
the anterior border of the transverse pelvic ligament (see Plate 2-5). The deep
dorsal vein then divides into branches that join the prostatic venous plexus.
This plexus of thin-walled veins, with similar veins from the bladder and rectum,
communicate freely with one another and with adjacent venous tributaries.
Ultimately, they empty into
the internal iliac veins.
