We begin with discussions of the various structures of the male sexual anatomy. Descriptive accounts are organized according to parts of the genital system for easy reference. Later in this chapter (and in Chapter 6) we will look more closely at the way the entire system functions during sexual arousal.
The Penis
The penis consists of nerves, blood vessels, fibrous tissue, and three parallel cylinders of spongy tissue. It does not contain a bone or an abundance of muscular tissue, contrary to some people’s beliefs. However, an extensive network of muscles is present at the base of the penis. These muscles help eject both semen and urine through the urethra.
A portion of the penis extends internally into the pelvic cavity. This part, including its attachment to the pubic bones, is referred to as the root. When a man’s penis is erect, he can feel this inward projection by pressing a finger upward between his anus and scrotum. The external, pendulous portion of the penis, excluding the head, is known as the shaft. The smooth, acorn-shaped head is called the glans.
Running the entire length of the penis are the three cylinders referred to earlier. The two larger ones, the cavernous bodies (corpora cavernosa), lie side by side above the smaller, third cylinder, the spongy body (corpus spongiosum). At the root of the penis the innermost tips of the cavernous bodies, or crura, are connected to the pubic bones. At the head of the penis the spongy body expands to form the glans. These structures are shown in I Figure 4.1.
All these cylinders are similar in structure. As the terms cavernous and spongy imply, the cylinders are made of spongelike irregular spaces and cavities. Each cylinder is also richly supplied with blood vessels. When a male is sexually excited, the cylinders become engorged with blood, resulting in penile erection. During sexual arousal the spongy body may stand out as a distinct ridge along the underside of the penis.
Male Sexual Anatomy and physiology
The skin covering the penile shaft is usually hairless and quite loose, which allows for expansion when the penis becomes erect. Although the skin is connected to the shaft at the neck (the portion just behind the glans), some of it folds over and forms a cuff, or hood, over the glans. This loose covering is called the foreskin, or prepuce. In some males the foreskin covers the entire glans, whereas in other males only a portion of the glans is covered. Typically, the foreskin can be retracted (drawn back from the glans) quite easily. Circumcision involves the surgical removal of this sleeve of skin. Although familiar in our culture, circumcision is only one of many procedures for altering male genitalia that are practiced around the world, as described in the following Sexuality and Diversity discussion on male genital modification and mutilation.
SEXUALITY and DIVERSITY