The Human Penis

Along with the testicles, the penis is one of the male external genital organs. The organ serves to excrete urine and for reproduction. Its shape and function when erect are primarily intended for penetration into the female body.

The penis can be injured relatively easily during sexual intercourse, although most injuries are minor. Aside from a brief uncomfortable sensation, abrasions and small skin tears pose virtually no risk.

In rarer cases, penile rupture can occur due to bending trauma while the penis is erect. This involves a rupture of the corpora cavernosa, which in most cases is accompanied by massive hematomas. Applying cold compresses and elevating the penis and testicles is the best treatment following accidents during sexual intercourse.

Sexually Transmitted Diseases

Sexually transmitted diseases such as syphilis and gonorrhea often manifest on the penis in men. The formation of smegma, redness, and itching can be signs of infection. To protect against possible infection, a condom should be used during sexual intercourse. More information on specialists in sexually transmitted diseases. 

Non-Transmissible Diseases and Their Treatment

Erectile dysfunction is the most common disorder affecting the male penis. It can have both psychological and physical causes and is classified as either primary (congenital) or secondary (acquired).

The most common causes of organic dysfunction are circulatory disorders, diabetes, and excessive nicotine use. Less common are hormonal and neurogenic causes, such as multiple sclerosis. Erectile dysfunction often occurs as part of a syndrome and is attributable to multiple underlying factors.

Drugs or medications can also trigger priapism, which is a persistent erection of the penis. This persistent erection can be very painful for the patient and requires prompt treatment. Injections can help within the first few hours. In severe cases, surgical shunts must be implanted, which can significantly impair the penis’s future function.

Penile Malformations

Congenital malformations of the human penis occur in rare cases:

• A micropenis is a form of underdeveloped genitalia and refers to an unusually small penis.
• In the (extremely rare) condition known as diphallia, two penises are situated side by side.
• The most common malformation involves the position of the urethra: it opens at a location other than the tip of the penis. This is generally more of a cosmetic issue; function is usually unaffected.
• Many penises are not completely straight when erect. However, if they deviate significantly from a straight line, this is referred to as penile curvature. Penile curvature requires treatment only if it causes pain or makes sexual intercourse impossible.

Prevention, Diagnosis, and Treatment

In medicine, urology is the specialty that deals with diseases of the penis and all male organs related to urination and reproduction. The field is heavily focused on surgery, which is why urologists are usually trained in all forms of surgical treatment for penile conditions.

Starting at age 40, men are advised to see a urologist regularly to prevent prostate diseases and cancer. Routine preventive examinations include palpation of the testicles, abdomen, and prostate. Men should also regularly check for hardening or lumps through self-examination, even at a younger age, especially if there is a family history of prostate cancer.

The male penis consists of

• the root of the penis
• Penile body or shaft
• Glans

The root of the penis refers to the proximal end of the penis, which is connected to the pelvis by ligaments and muscles. The muscles in the area of the root of the penis trigger erections by contracting and compressing the veins that drain blood from the penis.

The penile shaft makes up the largest part of the organ and consists of three corpora cavernosa and the urethra. During sexual arousal, the corpora cavernosa fill with blood, thereby causing an erection. On the underside of the penis is a visible fusion line of the corpora cavernosa, known as the penile suture.

The distal tip of the penis is called the glans. It consists of another erectile body, the corpus spongiosum glandis. At the tip of the glans is the urethral opening, through which urine and semen are expelled.

The penile sulcus runs between the shaft of the penis and the glans. In uncircumcised men, the glans is protected by the foreskin, which is connected to the penile sulcus by the frenulum.

A man’s testicles are located directly below the base of the penis. During ejaculation, seminal fluid is transported from the testicles through the vas deferens into the erect penis and expelled through the urethral opening.

The structure of the human penis is typical of all mammals. Beginning around the ninth week of embryonic development, the genital tubercle—common to both sexes—develops into the penis.

Regardless of body height, the penis can take on different shapes in both the erect and flaccid states. Its shape is primarily determined by the structure of the internal erectile tissues and their blood supply.

When erect, an average penis is between 12 and 17 cm long and has a diameter of about 4 cm. When flaccid, the average penis measures between 7.5 and 11 cm, with a diameter of about 3 cm. As a rule, the glans has a larger circumference than the shaft of the penis and remains more elastic when erect.

There are also visible differences in the curvature of the penile shaft, although function is not impaired by its shape.

Sperm cells enter a woman’s internal reproductive organs via the penis. Sperm cells carry the man’s genetic material and pass this genetic code on to the woman’s egg. A vasectomy—that is, the surgical severing of the vas deferens—can artificially prevent the penis from performing its reproductive function.

The human penis is a complex organ whose structure and function are closely linked to the interaction of tissues, blood vessels such as the dorsalis penis, and structures such as the radix penis and bulbus penis. An erection occurs during sexual arousal when the three erectile tissues—including the corpora cavernosa and the corpus spongiosum—fill with blood, resulting in an erect penis.

Anatomical structures such as the frenulum praeputii (frenulum of the foreskin), the underside of the penis, and the sides of the penis are also important components of the human penis.

Penile disorders such as induratio penis plastica, erectile dysfunction, phimosis, or cancer can impair function and affect the external male genitalia, including the penis and scrotum. Overall, it is evident that the penis, as the male organ, plays a central role in both the penises of mammals and the human penis, with factors such as sexual arousal and the retraction of the foreskin being crucial for normal function.