Anatomy 101: Penile & Testicular Anatomy

Anatomy 101: Penile & Testicular Anatomy

In a continuation of our review of genital anatomy, we will discuss penile and testicular anatomy and this area’s role in pleasure. As we review, we will see the similarities and differences between the genitals whether someone is assigned male or female at birth.

Front and Center

The primary sex organ in this anatomy is the penis and, unlike the vagina, it is located externally. The penis begins just below the mons pubis and the area closest to the body is the shaft. The urethra is a tube located inside the shaft of the penis; it allows urine to exit the bladder and then be released from the tip of the penis. Also located in the shaft is the corpa cavernosum: these are two cylinders located on the top side of the penis. 1  With arousal these cylinders fill with blood and the penis changes from being soft and flaccid to being hard and erect. As blood enters the corpa cavernosum, the cylinders increase in size between two to five times their original volume and this is how the length of a penis changes drastically with an erection. 1

The shaft leads into the head (also known as the glans) of the penis. This area is the most sensitive part of the penis and contains the opening where, depending on the state of arousal pre-cum or cum exit the body. 2 About 50% of penises in the US have been circumcised, meaning that the skin at the end of the penis that encompasses the head has been removed. In most people, it is removed right after birth but some have the tissue removed later in life. A circumcised penis will have a clear head or glans (creating the characteristic mushroom shape at the end of the penis) whether aroused or not, an uncircumcised penis will have skin covering over the head when flaccid. With arousal the foreskin is sometimes drawn backward so that the head is visible; when erect, circumcised and uncircumcised penises can look similar. The foreskin attaches to the frenulum which is located on the underside of the penis and forms a V shape. 2 The frenulum is present whether or not circumcision has occurred and tends to be a very sensitive and pleasurable area. 2

The Undercarriage

Dangling just behind the penis is the scrotum, a skin sac that encompasses the two testicles. The scrotum is wrinkly and usually covered in hair. There is no standard size of a scrotum and it can vary in color as well as symmetry between sides. 2 The main purpose of the scrotum is to maintain the correct temperature for the testicles because the testicles have the vital job of creating sperm and hormones. 2 When the scrotum encounters cold temperatures, the cremaster muscles draws the testicles upward toward the body. The cremaster muscle also draws the testicles upward with arousal or with a light touch to the inner thigh. 2 Warm temperatures will result in the scrotum moving the testicles away from the body. 2 The scrotum can also act as a pleasure center during intimacy but this area is incredibly sensitive so light touch is often most enjoyable.

Behind the scrotum lies the perineum. The perineum is the correct anatomical term but you may know it better by one of its many slang terms like taint or grundle. Everyone has a perineum and light pressure to this area can heighten sexual pleasure. Just as in the vulva, the perineum in someone with a penis is where many of the pelvic floor muscles attach. We will discuss the pelvic floor more in depth in our next instillation of this series. 


The Backdoor

We can’t discuss pleasure in this area and leave out the prostate. The prostate is located just below the bladder, it is a gland that secretes fluid that helps the sperm move and survive. 2 Cum (also known as ejaculate) is made up of sperm from the testes, fluid from the prostate, semen from the seminal vesicles, and fluid from the Cowper’s glands. 3 The seminal vesicles produce semen (not to be confused with sperm) and sperm travels in this fluid. 2 The Cowper’s glands produce precum, this is released prior to cum and it preps the urethra for ejaculate by reducing friction. 2 The prostate is sometimes referred to as the “p-spot” or the “ (cis-)male g-spot” because touching this area can be so arousing. The prostate can be accessed internally via the rectum (about two inches inside the anal canal) or externally through the perineum. 4 If you’re going to stimulate the prostate internally, remember to use lubricant on the finger, toy, or body part being inserted. Any toy being used internally should have a base to make sure it does not get stuck inside the rectum.

This is a brief lesson on penile and testicular anatomy! Hopefully it left you more knowledgeable about the area and feeling empowered in your ability to pleasure yourself or your partner. Take the time to explore the area and see what you and your partner like or don’t like, and remember to enjoy yourself! The books and articles referenced here are a great way to expand your understanding as well.


Photo References:




  1. The Penis Book by Aaron Spitz, MD
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