Male Sexual Anatomy & Physiology

Male Sexual Anatomy The penis foreskin, glans, shaft, & root

Male Sexual Anatomy Penis - formed of three cylindrical masses of erectile tissue - enclosed in separate fibrous coverings - held together by a covering of skin Root at base of penis, divides into crura which are attached to the pelvic bones Glans is at the tip of the penis and is the most sensitive part for most men - covered by prepuce or foreskin which may be removed by a surgical procedure called circumcision smegma - secretion that can accumulate under foreskin of penis (or clitoris) – uncircumcised men should clean beneath the foreskin thoroughly when they wash to prevent excess accumulation of smegma Corona (crown) - ridge between glans and foreskin (see next slide) Frenulum - connects glans to shaft on underside of penis (see next slide)

Corona and Frenulum http://www. thevisualmd. com/searchimg/ This figure, a view of the underside of the penis, shows the location of the corona and frenulum—two areas on the penis that harbor a high concentration of sensitive nerve endings.

Shaft - contains spongy tissue which fills with blood when a man is aroused, leads to erection (there is no bone in the penis) Cavernous bodies (corpus cavernosum) - on top - 2 of them Spongy body (corpus spongiosum) underneath - 1 only - urethra runs through it

Penises come in a variety of shapes and sizes… http://www

The Scrotum loose pouch or sac of skin beneath the penis with two chambers that hold the testicles, one testicle in each sac testes are suspended in the sacs by the spermatic cord which carries sperm out of the testes in the vas deferens cremaster muscles pull testes closer to body in cold temperatures – to produce viable sperm, the testes must be at the right temperature, and these muscles allow testes to be raised or lowered to control the temperature The spermatic cord can be located by palpating the scrotal sac above either testicle with thumb and forefinger.

Testes -http://www.youtube.com/watch?v=gAnMymnJiLM Spermatogenesis: process of sperm production Seminiferous tubules are the site of sperm production sperm maturation occurs in the epididymus (about 20 feet long) on the back of each testicle Interstitial cells are located between the seminiferous tubules and are the major producer of androgens in men 200 million sperm/day!! Internal structure of a testis. Sperm are produced in the seminiferous tubules and transported to the epididymis, which serves as a storage chamber.

Vas Deferens Extension of epididymus (about 18" long) – vas is carried into pelvic cavity through the spermatic cord, over the top and down back/side of bladder – Vasectomy involves severing the vas deferens

Seminal vesicles - two pouch-like structures between the bladder and the rectum - function not completely understood – they secrete an alkaline fluid rich in fructose - sperm become motile here and can propel themselves (got to this point via cilia in ducts) Ejaculatory ducts - formed from the union of the vas deferens and the excretory duct of the seminal vesicles Prostate gland - doughnut shaped gland just below the bladder - thin alkaline secretions counteract acidity in male urethra and in the vagina –

Cowper's glands (or bulbourethral glands) pea-sized - lie just below prostate - connect to urethra by a duct - secrete a slippery substance when a man is sexually aroused - alkaline - helps lubricate flow of seminal fluid through urethra can contain active sperm and cause pregnancy without ejaculation occurring Semen (or seminal fluid) one teaspoon of fluid – one ejaculation contains 200-500 million sperm which - provide only 1% of volume - rest from seminal vesicles (70%), prostate (30%) and Cowper's gland semen of a healthy man is not harmful if swallowed – but semen can transmit HIV from an HIV-positive man

Erection Controlled by the autonomic nervous system (which is generally involuntary in its actions) - arteries expand, and when blood outflow can’t keep up with inflow, tumescence (erection) occurs Erections occur from birth (and apparently before), occur during REM sleep throughout life – clearly not always due to sexual stimulation Psychological factors can enhance or inhibit erections

Process of ejaculation occurs in two stages; Emission phase: The cremaster muscle pulls the testes up close to the body preparing to release sperm Ejaculatory inevitability: During intercourse, the point when semen is about to be secreted

Expulsion phase: Ejaculatory ducts: Two short ducts located within the prostate gland that transport sperm to the urethra prior to ejaculation

Penis Size Many cultures are preoccupied with penis size, not just a U.S. phenomenon - worship of the penis is one of the oldest known religious practices (as is worship of the goddess and female fertility) Large size not related to better sex - partner preferences vary Some pain occurs if sizes don’t match  Size not related to size of other body parts Bigger differences in size when flaccid than when aroused, i.e., smaller flaccid penis usually increases in size more during erection than a larger flaccid penis The largest?

Did you know? A study on penis size with over 3,000 men found that most men who sought penis enhancement because they were dissatisfied with their penises were within the normal size range and greatly overestimated the size of an average penis (Dillon, et al., 2008). These men thought the average flaccid size was about 5 inches, although some thought it was as long as 6.5 inches. Men get their ideas about penis size mostly from porn, where male performers have penises that are longer than average. In reality, a 7-inch erect penis would place you in the 99th percentile.

Penis Enlargement This is the before photo

Penis Enlargement This is the after photo Fat injection Cutting the ligaments

Penis Enlargement Some men go for the stretch (“gelking”) with weights attached

Male Genital Health Concerns Most often want to consult with a urologist for male genital health concerns (if primary care doctor can’t take care of problem) Penis health-care issues cleanliness: uncircumcised men need to be sure to remove smegma from under the foreskin it is possible for penis to have a negative reaction to some vaginal secretions resulting in a condition similar to eczema some sex toys (gadgets) are hazardous to the penis, e.g., cock rings that help maintain an erection can destroy tissue in the penis if left on too long, and text says they should never be used NEVER masturbate with vacuum cleaner type devices

Cancer Penile cancer: rare, but deadly if not treated early Testicular cancer: rare, but more common in young men (20-35 yrs old)- results in hard or irregular mass in a testicle sometimes grows rapidly, and it is very important to detect and treat early…p. 120 exam