



And



" "As you become more turned on, blood continues to flood the pelvic area, breathing speeds up, heart rate increases, nipples become erect, and the lower part of the vagina narrows in order to grip the penis while the upper part expands to give it someplace to go." www.womenshealthmag.com/sex-an… And

During orgasm the body stiffens and the muscles contract. Involuntary muscle contractions and spasms may occur in various parts of the body, including your legs, stomach, arms, and back. The muscles of the vagina relax and contract rapidly, as do the muscles of the uterus." www.livestrong.com/article/124…

It both expands and contracts, this is normal during sex. In my story his head is deepest, and his mid point would be about the place where the squeezing starts, down to his feet it would get tighter. Trying to get technical about it would ruin the bit, but if you must here is how it actually works...