The bulb of penis refers to the bottom portion, or base, of the penis. The bulb is located above the scrotum, which contains the testicles.

The bulb is composed of a large bundle of tissue. In conjunction with five other components, the bulb forms the internal structure of the penis and the visible, external shape of the penis. The bulb appears as a prominent ridge on the shaft of the penis.

This tissue mass expands from the muscle known as the corpus spongiosum. This corpus spongiform is attached to the perineal membrane that extends from the perineum, the area between the scrotum and anus. From the bulb, the corpus spongiform travels up the length of the penis along the urethra to form the glans at the top of the penis. The urethra, the tube through which urine and semen exit the body, extends from the bulb. The surface of the bulb is surrounded by bulbospongiosus muscle.

The internal pudendal vein drains blood from the bulb, while the internal pudendal artery supplies the bulb of penis with blood.

The bulb of the vestibule, similar to the bulb of the penis, is present in women.