The baculum (also penis bone, penile bone, os penis, os genitale or os priapi) is a bone found in the penis of many placental mammals.

It is absent from the human penis, but present in the penises of some primates, such as the gorilla and the chimpanzee. The baculum arises from primordial cells within soft tissues of the penis, and its formation is largely under the influence of androgens. The bone is located above the male urethra, and it aids sexual reproduction by maintaining sufficient stiffness during sexual penetration.

The homologue to the baculum in female mammals is known as the baubellum (also os clitoridis or os clitoris), a bone in the clitoris.

Not to be confused with penile spines.

Baculum - From Wikipedia, the free encyclopedia