I know the ass is sensitive, but how many nerve endings are there in the ass? Is it the same in guys and girls? And are the “good feeling nerves” located in the sphincter or the rectum?

–Curious About Anatomy

The anus (the anal opening), the anal canal (the first few inches inside), and the rectum are all sensitive in different ways, which is why anal stimulation and penetration can be so pleasurable. The external and internal sphincter muscles surround the anal opening. These muscles can work together or independently of each other, and these are the muscles we must learn to relax in order to achieve comfortable anal penetration. When we talk about the sphincter and pelvic muscles and how they play a role in anal pleasure, we discuss them less in terms of sensitivity and more in terms of how tone and “in shape” they are and how tense or relaxed they are. The anus and the outer part of the anal canal are made of the same sensitive soft tissue and this tissue contains the most concentration of nerve endings of all our anal anatomy. In general, this tissue tends to be more sensitive to touch and vibration. The inner part of the anal canal and the rectum are mucous membrane and have a lot less nerve endings; however this tissue is much more sensitive to pressure (like from penetration).

Men and women have nearly identical anorectal anatomy except for one important difference: men have a prostate gland, which can be stimulated directly via anal penetration. The prostate gland surrounds part of a man’s urethra; it’s behind the pubic bone, below the bladder and above the base of the penis. A mass of muscle, glands, and connective tissue, the prostate is about the size and shape of a walnut; it produces ejaculatory fluid that combines with sperm and fluid from the seminal vesicles to create male ejaculate. Men can experience direct prostate stimulation when they are anally penetrated. It can be found by sliding a finger (or toy) about one to two inches inside a man’s ass and aiming toward the front of his body.

While women don’t have a prostate, but we do have a G-spot and can experience indirect G-spot stimulation through anal penetration. The G-spot is the urethral sponge which sits around the urethra; to find it, slip a finger inside her vagina an inch to an inch and a half and toward the front of her body. The G-spot can be stimulated through the front wall of the vagina or indirectly though anal sex.