Over the last several years, we have gained a much better understanding of the physiology of erectile function. This understanding has led to the development of many of the treatments that we are all so familiar with.

An erection occurs when the two erectile bodies of the penis known as the corpora cavernosum fill with blood. As the corpora fill with blood the penis becomes engorged. In order for the erection to proceed to maximum rigidity, the blood must be trapped by sinusoids (venous...