Just outside the crus of the penis, the pudendal artery branches into the dorsal penile artery, which courses distally between the tunica albuginea of the corpora cavernosa and Buck's fascia, and the deep penile artery, which penetrates the crus and courses distally within the corpus cavernosum as the deep (central) artery. The dorsal artery gives off circumflex branches that perforate the tunica albuginea, particularly near the distal end of the corpora, and also supplies a portion of the glans penis.

The deep central arteries supply nutrient vessels to the trabeculae, anastomoses that cross the septum to the opposite corpus cavernosum, and the helical arteries, which arborize into short-end arterioles. These helicine arterioles open directly into the cavernous spaces; in the erect organ, they relax, allowing rapid inflow with exposure of the lacunar spaces to systemic arterial pressures.

The blood supply to the glans, or head, of the penis is part of a separate system. It is for this reason that men can achieve an erection without swollen glans, such as in conditions known as priapism. This is also true for men who have penile implants; the glans or head of the penis will not become enlarged.

Venous Drainage
Venous drainage of the penis is complex and intercommunicating. It is accomplished by at least three major pathways

The superficial dorsal vein, which lies superficial to Buck's fascia and is formed from multiple subcutaneous veins

The superficial dorsal vein drains primarily to the saphenous and pudendal veins. The deep dorsal vein arises from a retrocoronal plexus and is joined by circumflex veins that drain the cavernous sinus spaces via emissary veins, which perforate the tunica albuginea both dorsally and ventrally to join the circumflex veins. The corpora spongiosa is also drained in part by emissary vessels to the circumflex veins. The deep and superficial dorsal veins anastomose proximal to the coronal sinus, just distal to the pubic symphysis.

The cavernous veins emerge from the proximal end of each corpora cavernosa to drain into the pudendal system. The bulbar and urethral veins drain the proximal corpus spongiosum. The deep dorsal penile vein passes under the pubic arch to trifurcate, forming lateral venous plexuses that ultimately drain to the pudendal plexus in the pelvis.

Innervation
Both divisions of the autonomic nervous system as well as the somatic system contribute to the innervation of the penis Sympathetic nerves that originate from the eleventh thoracic to the second lumbar spinal segments course retroperitoneally to form the superior hypogastric plexus (presacral nerve) located beneath the aortic bifurcation. Sympathetic fibers leave the plexus as right and left hypogastric nerves, which fuse to contribute to the inferior hypogastric (pelvic) plexus. Found retroperitoneally beside the rectum, the pelvic plexus forms a fenestrated rectangular plate, which is perforated by branches of the inferior vesical arteries and veins.

Parasympathetic nerves from cell bodies in the second and third sacral spinal segments (S2-4) also contribute to the pelvic plexus via the pelvic nerve. Although it is relatively impossible to identify the origin of nerves leaving the pelvic plexus, those that innervate the corpora cavernosa are situated between the rectum and urethra to enter the urogenital diaphragm near or in the urethral wall, and from there, the dorsal medial side of the corpora cavernosa.

Sensory innervation of the penis is supplied by the pudendal nerve, whose cell bodies are also located in S2-4. The nerve travels with the internal pudendal vessels along the lateral wall of the ischiorectal fossa. The dorsal nerve of the penis is a terminal branch of the pudendal nerve.