Impotence is the inability to obtain and maintain an erection of the penis, which is necessary to penetrate the vagina during sexual intercourse.

Internal spaces in the penis (called corpora cavernosa) normally fill with blood during sexual excitement and cause the penis to become rigid and erect. Impotence is a partial or total impairment of this function. There are two types of impotence. Primary impotence is when a man is never able to have an erection adequate for sexual intercourse to the satisfaction of both partners. Secondary impotence is the more common type.

Erection takes place when structures inside the penis and along the urethra between a mans legs are filled with blood and inflated. This occur upon signals from the brain and the spinal cord, and the signals are transmitted through nerves in the parasympatic nervous system, a part of the autonomous or involuntary nervous system.

HOW THE NERVOUS SYSTEM TRIGGERS AND CONTROLS THE ERECTION

The erection is triggered and controlled by the following events: