The penis is an unpaired external male reproductive organ which participates in the excretion of urine and sperm.

The penis consists of several parts:

Root (or radix) - the proximal part of the penis that is attached to the pubic bone bone and ischium; fixed to the pubic symphysis;
Body - the middle part, formed by three columns of erectile tissue: two cavernous bodies and one spongious body;
Glans penis - the distal part of the penis, also called the head of the penis; the narrow ending of the corpora cavernosa and corpus spongiosum, also the urethra enters the glans penis; urethra ends with the external urethral orifice; the neck of the glans is the part separating the glans from the body of the penis.

The body and glans penis form the mobile part of the penis, while the root is the only part that is fixed. The anterior surface of the penis is called the dorsum of penis, while the posterior - the urethral surface.

Both corpora cavernosa are located next to each other throughout all parts of the penis, more on the dorsum part of the body, while the corpus spongiosum is located closer to the urethral surface and is located in the middle between both corpora cavernosa.

In the root of the penis, the corpora cavernosa end with the crura of penis - pointed ends located more laterally and attached to the pubic bone and ischium.

On the dorsal surface between both corpora cavernosa is a longitudinal dorsal groove in which are located dorsal blood vessels and nerves, while the urethral surface contains a ventral groove for corpus spongiosum.

The corpus spongiosum has a spongy structure, and it is thinner than corpora cavernosa. In the radix is located one of its expansions called the bulbus penis (located between crura of penis). The spongy part of the urethra starts here.

Previously mentioned glans penis is the distal expansion of the corpus spongiosum that is bell-shaped.

The margin of the glans penis that demarcates the border between the body and glans is called the corona of glans penis.

The corpus spongiosum transmits the penile part of the urethra which ends with the external urethral orifice.

Penis is related to two skeletal muscles called the ischiocavernosus and bulbospongiosus muscles. Muscles are attached to the root of the penis, and they mainly function to erect the penis (ischiocavernosus) and ejaculate the sperm (bulbospongiosus).

Corpora cavernosa and corpus spongiosum are covered by the inner (circular fibers) and outer (longitudinal fibers) layers of the tunica albuginea, which is covered by the following layers (innermost to outermost) deep fascia of penis (also called Buck's fascia), subcutaneous tissue of penis (areolar tissue), Dartos fascia, and skin.

The skin of the penis is wrinkled and it does not contain subcutaneous fat, and it is very thin and mobile.

At the glans penis region, the skin forms a double layer fold - the foreskin, which partially covers the glans. The foreskin is attached to the urethral surface with the help of the frenulum. The foreskin and corona contain glands that secrete sebaceous smegma that is collected in the space between the foreskin and glans penis. This secretion protects the skin surface from drying out, it reduces friction and makes the skin elastic.

There is a high concentration of nerve endings in the penile skin.

The main functions of the penis are:

Urination
Ejaculation of sperm and reproductive function
Sexual intercourse and pleasure

Scrotum

The scrotum is a paired pigmented skin and muscle sac that contains the testicle, epididymis and their covering layers, blood vessels, and nerves, as well as the initial part of the spermatic cord.

The main function of the scrotum is to provide the required temperature for spermatogenesis as this process requires a lower temperature than the body. The testicles are located outside of the male body because of the scrotum.

The scrotum has only two layers:

Skin
Dartos fascia (under the skin)

The skin of the scrotum is thin, wrinkled, pigmented, and contains many sebaceous and sweat glands. The raphe of the scrotum is visible on the outer, middle part of the scrotum, both front and back of the organ.

The wall is made up of elastic fibers and smooth muscle cells known as the dartos fascia, but it lacks fat cells. This muscular lining under the skin is partially attached to it. The skin of the scrotum crinkles when the muscular lining contracts.

Dartos fascia forms a sagittally oriented scrotal septum. It divides the scrotum into two parts, each contains one testicle, and it joins the raphe of the scrotum in the anterior and posterior surface of the scrotum.

Note: The muscle fibers attached to the dartos fascia relax in warm weather, allowing the testis to descend and regain the optimal temperature. The opposite happens during cold weather when the testis ascends closer to the body.

Unlock with Premium

Penis and scrotum