The perineal sponge is a spongy cushion of tissue and blood vessels found in the lower genitals of women. It sits between the vaginal opening and rectum and is internal to the perineum and perineal body.
Functions
The perineal sponge is composed of
erectile tissue; during
sexual arousal, it becomes swollen with
blood compressing the outer third of the vagina along with the
vestibular bulbs and
urethral sponge thereby tightening the vagina and increasing stimulation for the vagina and a penis, if involved.
[Levine S. et al. "Handbook of Clinical Sexuality", page 180 Brunner-Routledge 2003 ]
Sexual stimulation
The perineal sponge is erogenous tissue encompassing a large number of
nerve, and can, therefore, be stimulated through the back wall of the
vagina or the top wall of the rectum.
[Chalker R. "The Clitoral Truth", page 46 Seven Stories Press 2000 ]