The penis - anatomy, functions and common diseases

Leading Medicine Guide Editors
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Leading Medicine Guide Editors

The penis is the primary male sexual organ for reproduction and urination. Its shape can vary greatly from man to man.

Article overview

The penis

Alongside the testicles, the penis is one of the external sexual organs of the male. The organ is used to excrete urine and for reproduction. Its shape and function when erect are mainly intended for insertion into the woman.

Männliche Geschlechtsorgane

Injuries, diseases and malformations

The penis can be injured relatively easily during sexual intercourse, although most injuries are minor. Apart from a brief unpleasant sensation, abrasions and small tears in the skin pose little risk.

More rarely, penile rupture can occur as a result of bending trauma when erect. This is a rupture of the erectile tissue, which in most cases is accompanied by massive hematomas. Cooling and elevating the penis and testicles is the best treatment after accidents during sexual intercourse.

Penisruptur

Sexually transmitted diseases

Transmissible sexually transmitted diseases such as syphilis and gonnorhoea often manifest themselves 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 put over the penis during sexual intercourse.

Non-communicable diseases and their treatment

Erectile dysfunction is the most common disorder affecting the male penis. These can have both psychological and organic causes and are divided into primary, i.e. congenital, and secondary, i.e. dysfunctions that occur later.

The most common causes of organic dysfunctions are circulatory disorders, diabetes and excessive nicotine consumption. Less common are hormonal and neurogenic causes such as multiple sclerosis. Erectile dysfunction often occurs as part of a syndrome and is caused by several causal factors.

Priapism can also be triggered by drugs or medication. This is a permanent erection of the penis. The permanent erection can be very painful for the patient and requires rapid treatment. Injections can help in the first few hours. In severe cases, shunts have to be surgically created, which can severely impair the subsequent function of the penis.

Malformations of the penis

Congenital malformations of the human penis occur in rare cases:

  • A micropenis is a form of underdeveloped sexual organs and refers to an unusually small penis.
  • In the (extremely rare) case of diphallia, two penises are located next to each other.
  • The most common malformation concerns the position of the urethra: it ends at a different point than the tip of the penis. As a rule, this is more of a cosmetic problem; function is guaranteed in most cases.
  • Many penises are not completely straight when erect. However, if they deviate significantly from the straight axis, this is referred to as penile curvature. Penile curvature only requires treatment if it causes pain or makes sexual intercourse impossible.

Prevention, diagnosis and treatment

Within the field of medicine, urology deals with diseases of the penis and all male organs associated with urination and reproduction. The field is strongly influenced by surgery, which is why urologists are usually trained in all surgical forms of treatment for diseases of the penis.

Find Specialists for Urology

From the age of 40, men are recommended to see a urologist regularly to prevent prostate diseases and cancer. Routine check-ups include palpation of the testicles, abdomen and prostate. Men should also regularly check for hardening and lumps by palpation at a younger age, especially if there is a family history of prostate cancer.

Anatomical structure of the penis

The male member consists of

  • penis root
  • penis body or penis shaft
  • glans

The root of the penis is the proximal end of the penis, which is connected to the pelvis by ligaments and muscles. The muscles at the base of the penis trigger erections by contracting and squeezing outflow veins.

Der Penis und die männliche Anatomie
The position of the prostate © Henrie / Fotolia

The body of the penis forms the largest part of the organ and consists of three corpora cavernosa and the urethra. The erectile tissue fills with blood during sexual arousal and thus ensures an erection. On the underside of the penis there is a visible fusion of the erectile tissue, the penile suture.

The distal tip of the penis is called the glans. This consists of another erectile tissue, the corpus spongiosum glandis. The urethral orifice, from which urine and semen emerge, is located at the tip of the glans.

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

A man's testicles are located directly below the base of the penis. During ejaculation, seminal fluid is passed from the testicles via the vas deferens into the erect penis and excreted via the urethral orifice.

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

Size and shape of the penis

Irrespective of body size, the penis can take on different shapes when erect and when not erect. The shape is mainly determined by the condition of the internal erectile tissue and its basic blood supply.

When erect, the average penis is between 12 and 17 cm long and has a diameter of around 4 cm. Without an erection, the average phallus measures between 7.5 and 11 cm with a diameter of around 3 cm. As a rule, the glans has a larger circumference than the penis shaft and remains more elastic when erect.

There are also visible differences in the curvature of the body of the penis, although the function is not affected by the shape.

Function of the penis

Sperm cells enter the woman's internal sexual organs via the penis. Sperm cells carry the man's genetic material and pass this genetic code on to the woman's egg cell. The reproductive function of the penis can be artificially prevented by a vasectomy, i.e. the surgical severing of the vas deferens.

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