The human penis does not have a bone, and it is not a bone structure. Unlike some animals, such as many mammals that have a bone in their penis called a baculum, the human penis is composed of spongy tissue, blood vessels, and connective tissue.
In humans, the penis contains three cylindrical structures:
- Two corpora cavernosa: These are two large columns of erectile tissue that run along the top side of the penis.
- One corpus spongiosum: This surrounds the urethra and runs along the underside of the penis.
During sexual arousal, these erectile tissues fill with blood, causing the penis to become erect and firm, allowing for sexual activity. The absence of a bone in the human penis allows it to be flexible and capable of engorging with blood to facilitate sexual function.