The vaginal vestibular bulb is located deep to both sides of the vaginal vestibule and is a spongy, hoof-shaped structure composed of a venous plexus surrounded by a leucomembranous membrane.
The vaginal vestibular bulb is juxtaposed with the sito shame branch and is partially covered by the sciatic spongy muscles and vaginal retractor muscles. The lower portion of the vestibular bulb is generally in the middle of the vaginal opening, while its anterior end extends upward toward the clitoris. The vestibular bulb is surrounded by the vaginal sphincter and can be subjected to conscious innervation, and the woman is often able to control its contraction during intercourse.
Embryologically, the vestibular bulb is equivalent to the spongy body of the male penis. During labor the vestibular bulbs are often pushed underneath the pubic arch, but because they tail partially around the vagina, they are susceptible to injury resulting in vulvar hematomas and even heavy bleeding. Prompt medical attention is needed if any of these symptoms occur.