The corpus cavernosum is a sponge-like tissue in the male penis that is responsible for the erection of the penis. It is made up of two cylindrical structures that run along the length of the penis and contain numerous blood vessels and connective tissue. When a man is sexually stimulated, blood flows into the corpus cavernosum, causing the tissue to expand and the penis to become erect. The blood is then trapped in the corpus cavernosum, maintaining the erection. The corpus cavernosum also plays a role in ejaculation, as the semen is expelled from the penis through the urethra, which runs through the corpus cavernosum. In cases of erectile dysfunction, the corpus cavernosum may not fill with enough blood to cause an erection or may not be able to maintain the erection. Treatment for erectile dysfunction may involve medication, therapy, or surgical intervention.