Male Sexual Anatomy
The external male sexual anatomy includes the penis, scrotum, and testicles. The penis is made of three cylindrical bodies of erectile tissue that run from the head of the penis all the way into the perineum. The average penis size (measured from the pubic bone to the tip) is 4-6” (10-15 cm). The head of the penis (called the glans) is often the most sensitive, especially around the crown or corona, where the head meets the shaft. Men who are uncircumcised have a foreskin, which covers the head of the penis and is very sensitive.
During sexual arousal, tiny blood vessels in the penis relax, allowing more blood to flow into the erectile tissue. As this tissue fills up, valves in the outer layer of the penis are squeezed shut, increasing rigidity. Many health issues can decrease the blood vessels’ ability to relax, causing erection difficulties and most erection medications are designed to treat this. However, stress and anxiety can also keep the vessels from relaxing, which is why anxiety can also cause erection difficulties.
The skin of the scrotum is often very responsive to stretching or gently tugging. The testicles are held inside the scrotum, where they produce sperm. Sperm are then stored in the epididymis, which sits on top of the testicles. Sperm production is most efficient at a few degrees below body temperature, so the scrotum can regulate temperature by pulling up closer to the body when it’s cold and hanging lower when it’s warm. While the testicles are quite sensitive, many men enjoy the sensation of squeezing, tugging, or a vibrator on them.
Most men have two testicles, but some boys are born with only one. Since the testicles develop inside the body and descend into the scrotum, occasionally, one of them remains inside the body. If it doesn’t descend by puberty, it’s common to undergo surgery to either move it down or remove it. However, men with one testicle still produce enough testosterone for sexual development.
Most people only think of the external male sexual anatomy, but there’s a lot more going on inside. As arousal increases, the vas deferens pumps sperm from the epididymis into the body. At the same time, the prostate gland expands as it fills with prostatic fluid. The prostate is shaped like a donut and surrounds the urethra, the tube that urine runs through, and sits just under the bladder. The prostate is about the size of a small plum and is very sensitive to pressure and vibration, just as the G-spot is in women.
Both the prostate gland and the seminal vesicles produce the fluid that makes up semen. These mix together with the sperm in the urethra, which triggers the ejaculation reflex. This is the “point of no return” or “ejaculatory inevitability.” At this point, the muscles of the pelvis, including the PC muscle contract rhythmically, causing ejaculation. After ejaculation, the penis becomes softer as the blood vessels contract again. It can take some time before another erection is possible, although the length of time will vary from one man to another.The nerves in the anus and rectum are just as sensitive for many men as that are for many women. Anal pleasure has no relation to sexual orientation and if you’re interested in trying it out, please read Getting Started with Anal Sex for useful information about how to make it as fun as possible.