Male Sexual Anatomy
Arousal and Ejaculation:
During arousal, the entire sexual system engages in a series of specific events that result in erection and ejaculation.
The “erectile phase” occurs when increased blood flow into the corpus cavernosum tissues of the penis causes these erectile tissues to swell. This pulls the skin of the penis taut, exposing the high concentration of nerve endings and allowing increased sensation.
The phase known as “emission” or “ejaculation” takes place when the vas deferens contract and move sperm from the epydidymis up through the body. The sperm then passes through the ejaculatory ducts just behind the prostate, where it joins fluid created in the seminal vesicles (which nourishes the sperm) and fluid created in the prostate (which liquefies the ejaculate). The ejaculate enters into the urethra at the prostate and then a series of rhythmic muscular contractions propel the semen through the penis and out of the body. These contractions are often highly pleasurable.
The prostate is a gland about the size of a walnut, located just under the bladder in the pelvis.
The prostate is made of glandular, connective and muscular tissue. The main function of the prostate is to produce and secrete a fluid that liquefies the male ejaculate and provides secondary nourishment to the spermatozoa. The prostate has many small gland chambers, called acini, which produce and secrete Prostate Specific Androgen (PSA) into the prostatic ducts during the ejaculation process. This fluid combines with the spermatozoa and fluid from the seminal vesicles, and then flows into the urethra, through the penis, and exits the body as ejaculate. About 60% of the total volume of ejaculate is prostatic fluid, about 5% is spermatozoa and the remaining 35% is fluid from the seminal vesicles.
The prostate is quite small at birth, and gradually increases in size. In a man's late 20's there is a period of rapid growth, and then the size generally remains constant through adulthood. In their late 40's and beyond, many men experience growth and inflammation of the prostate. This growth can lead to prostate conditions such as benign prostate hyperplasia and prostate cancer. The prostate has two distinct zones. The outer layer, or peripheral zone, is where cancer is more likely to begin developing, and is also the zone that can be touched and examined through digital penetration of the rectum. The inner layer, or central transition zone, is where benign enlargement tends to begin.
Prostate health can be supported through many simple practices that can become a regular part of your healthy life. These include regular ejaculation, toning and stimulating the pelvic floor muscles, maintaining hormonal balance, and eating foods that nourish your cells, build immunity and detoxify. Awareness of the prostate's location and function can assist you in detecting any changes at a very early stage and enable you to seek immediate medical assistance.
The urethra is a tube that runs from the bladder to the tip of the penis, carrying both urine and ejaculate out of the body. The urethra begins at the bladder and passes through the prostate. Just above the prostate is the rhabdosphincter, which starts and stops the flow of urine, and also prevents urine from entering the urethra during arousal and ejaculation. This external urethral sphincter can be voluntarily contracted and toned. During arousal, fluid from the seminal vesicles and the prostate flow into the urethra and are ejaculated from the body through a series of muscular contractions. The urethra is named in three sections, from the bladder out: the prostatic urethra, bulbous urethra and penile or pendulous urethra.
Inflammation or cancer in the prostate can narrow the prostatic urethra and cause difficulty or pain in urination. Awareness of the urethra and healthy urination practices can help prevent urethral infections, urinary reflux and other conditions that compromise the health of the urethra and prostate. If you have any pain or difficulty urinating, please seek medical assistance.
The penis is perhaps the most familiar structure of the male pelvis. The penis extends from a bulbous root deep in the body, and is comprised of three tubes running lengthwise to form the shaft. Two are corpus cavernosum, which fill up with blood and become erect during arousal. Immediately below and between these two tubes is the corpus spongiosum, which then becomes the head/glans of the penis. The urethra runs through the corpus spongiosum and ends at the tip of the penis.
The entire penis has a high concentration of nerve endings, especially at the top, or glans. Protecting the highly sensitive tip of the penis is the foreskin, which in some men is removed in circumcision. The tissues and nerve endings of the penis can be stimulated during all states of tumescence (erection), and for many men the penis is a source of great pleasure. Many studies have recently linked sexual pleasure with health benefits in the body, ranging from an increased immune system to increased cardiovascular health.
The scrotum is an external structure that contains two testicles. Each testis contains several feet of tightly coiled tiny tubes, called seminiferous tubules. In these tiny tubes, sperm is produced and then transported to the epididymis where it matures and is stored until it travels up the vasa deferentia during ejaculation. In between the seminiferous tubules are the leydig cells which make testosterone and other androgen hormones.
Situated on the top of each testis, the epididymis is where sperm is matured and stored. Immature sperm arrive from the testes and are then matured in the upper part of the epididymis. Just before ejaculation, sperm move from the lower part of the epididymis into the vasa deferentia and then are moved upwards through the body to the ejaculatory ducts via peristaltic muscular contractions.
Originating at the epididymis, the two vasa deferentia (plural of vas deferens) carries mature sperm up through the body to the seminal vesicles, where it joins with seminal and prostatic fluid to form the ejaculate. The vasa deferentia is the strongest structure in the spermatic cords, woven ropes of arteries, veins, muscle and nerve that attach the testicles to the body. You can feel the vas deferens by palpating this cord and locating the hardest structure, which feels like a matchstick or tough cord.
The seminal vesicles are small sacs attached to the prostate and located slightly behind the bladder. The seminal vesicles produce and secrete fluid that feeds the spermatozoa. This fluid is pumped through the ejaculatory ducts and into the prostatic urethra. The vasa deferentia also connect at the ejaculatory duct, carrying sperm up through the body from the testis. Sperm is sometimes stored in the seminal vesicles, in addition to the epididymis.
The rectum is the last part of the colon, just inside of the anal sphincters. Feces is not stored in the rectum, but rather passes through during the active process of defecation. Through relaxation and opening of the anal sphincters, the rectum can be penetrated to allow stimulation and exam of the prostate.
The anus is the most external structure of the rectum, and consists of two sphincter muscles. The anus has one of the highest concentration of nerve endings in the human body, and is thus highly sensitive to both pleasure and injury. The sphincters of the anus are two strong circular muscles that open and close radially. The external sphincter is part of the voluntary nervous system, while the internal sphincter is controlled by the involuntary nervous system. Relaxing the sphincters, a natural function of this muscle body, can trigger relaxation to occur throughout the entire pelvis. Toning and relaxing constriction in these muscles is key to preventing hemorrhoids and fissures. With proper hygiene, the anus can be an integrated part of intimacy and can offer a wide range of pleasurable sensations.
The pelvic muscles are a complex web of muscles that together form a flexible and strong structure that keep all of the pelvic contents and abdominal organs in place. Most of these muscles stretch between the bony structures of the pelvis. The main muscles of the “pelvic floor” stretch from the pubis to the coccyx, forming the “pubococcygeal” or PC, muscle group. Becoming aware of this area, and then learning to relax and tone these central muscles, is essential to pelvic and sexual health. Toned pelvic muscles will strengthen your ejaculations, deepen the sensations of sexual arousal, and protect against incontinence. Toning these muscles also brings fresh, oxygenated blood to the pelvis, which is essential for maintaining prostate health. Contractions of the pelvic muscles are responsible for the ejaculatory process and essential for sexual pleasure.
The pelvis is a bowl shaped structure that is the structural foundation of the human body. The pelvis consists of five bones: the ilium, the ischium, the pubis, the sacrum and the coccyx. The ilium is the top and posterior (towards the back) bone of the pelvis- if you put your hands on your hips you are touching the ilium (the iliac crest, to be precise). The sacrum and coccyx are the lowest bones on your spine- the sacrum is the triangular bone just at the small of your back, and underneath that is our tail bone or coccyx. Underneath the ilium is the ischium, which include the ischial tuberosities or “sitz bones”. It is worth locating your sitz bones, as massage all around this area is highly pleasurable and relaxing. The front bone of the pelvis is the pubis, which has two parts partially fused together at the pubic symphsis. “Pelvis” means bowl in latin and it is helpful to think of your pelvis as a bowl containing your body's most precious and vital organs, the highest concentration of nerve endings and the skeletal and muscular foundation of the body. Maintaining a relaxed and strong pelvis is crucial to lifelong wellness and comfort.