The corpora cavernosa are two cylindrical structures located in the penis. They run along the length of the organ and are responsible for its rigidity during an erection. When a man becomes sexually aroused, blood flows into these structures, causing them to expand and harden. These tissues are made up of a network of blood vessels and smooth muscle. The corpora cavernosa work alongside the corpus spongiosum, which surrounds the urethra, to facilitate sexual function. Proper blood flow to the corpora cavernosa is essential for achieving and maintaining an erection.