The mechanism of erection requires the cooperation of the nervous system (central and peripheral) and the vascular system. The element which plays the central role in this process is the erectile tissue of the penis – a vascular structure built of numerous spaces. In a flaccid member, these spaces are almost empty and their walls are sunken. The vessels which supply blood to them are twisted and constricted – the blood bypasses them and goes through the so-called arteriovenous anastomoses. During erection, the spaces fill up with blood, stretching the tunica albuginea and increasing their volume, which results in the pressure on the penile veins, which prevents the blood from escaping the penis. The blood is delivered to the spaces mainly through the deep penile artery and, to a lesser extent, through the dorsal artery of the penis.Erection content