The corpus cavernosum is a cylinder with spongy structure located in the penis, which is called corpus cavernosum. The two sponges of the penis are located on the back of the penis, which are conical and pointed at both ends. The two parts are closely connected side by side. The anterior end is connected with the enlargement of urethral cavernous body, and the posterior branch is the angle of penis cavernous body, which ends at each pubic arch. Because the internal structure of this sponge is spongy, the penis can erect and expand when it is congested, and it can contract at ordinary times. The development of cavernous bodies on both sides is unequal, and the penis can bend to the underdeveloped side after erection; It is easy to repair the connection after an injury.

Each side of the dorsal penile artery sends out 1~2 arterioles, which enter the ipsilateral penile cavernous body at the junction (or distal end) of the penile cavernous body. This arteriole runs longitudinally in the penile cavernous body and sends out tiny branches. Some branches (300 ~ 400 microns in diameter) pass through the ventral part of the corpus cavernosum and enter the corpus cavernosum.

Other branches send out numerous tree-like branches in the cavernous body of penis, and these tiny branches further branch in the following two different forms: ① Arteries are divided into capillaries, which branch many times beside arterioles and finally form capillaries. These capillaries are scattered in sponge tissue, but they are especially dense around small blood vessels. After they are collected, they flow out of sponge tissue and are injected into the subcutaneous venous plexus. ② It is divided into spiral arteries, which gradually become thinner and send out communicating branches consistent with cavernous sinus (about 65438 00μ m in diameter).