An erection of the clitoris happens in the same way as an erection of the penis. The clitoris has a corpus cavernosum similar to the penis. However, instead of the corpus spongiosum it has two vestibular bulbs. When a woman is sexually excited, the corpus cavernosum and vestibular bulbs fill with blood. This causes the clitoris and other parts of the woman's sex organs to become larger, harder, and redder in color. When this happens, they become very sensitive to being touched.