Body & health

Penis

Alsopenisesphallusmale genitals

Not yet reviewed by a clinician. This health entry was written from the public-health sources listed below and is general information only. It is not medical advice.

Definition

The penis is an external genital organ in people typically assigned male at birth. It carries urine and semen out of the body through the urethra and becomes erect when its spongy tissue fills with blood.

At a glance

  • The penis carries urine and semen out of the body through the urethra.
  • It has a shaft and a rounded tip called the glans, which may be covered by a foreskin.
  • Erections happen when spongy erectile tissue fills with blood during arousal.
  • Penises vary in size, shape and curvature, and a slight curve is common.
  • New lumps, sores, discharge, pain or sudden changes in curvature or erections are reasons to see a doctor.

In detail

The penis has a shaft and a rounded tip called the glans, which may be covered by a foreskin unless someone has been circumcised. Inside are two columns of spongy erectile tissue and a third around the urethra. During arousal, blood flow increases and the tissue firms up, producing an erection.

Penises vary in size, shape and curvature, and a slight curve is common. New lumps, sores, discharge, pain, or a sudden change in curvature or in the ability to get erections are reasons to see a doctor or sexual health clinic.

In a sentence

  • The doctor reassured him that a slight curve in the penis is very common.
  • The puberty booklet explains how the penis and testicles grow during adolescence.

Where the word comes from

From Latin penis, which originally meant tail. It was adopted as the anatomical term in English in the 17th century.

Common questions

Is a curved penis normal?

A slight curve is common and usually nothing to worry about. A new or sudden change in curvature, a lump that can be felt, or pain during erections can be signs of a condition such as Peyronie's disease and are worth checking with a doctor.

How does an erection happen?

During arousal, blood flow to the penis increases and fills the spongy erectile tissue inside, which makes it firm. Erections depend on healthy blood vessels, nerves, hormones and mood, so ongoing difficulties can have physical or emotional causes and can be discussed with a doctor.

Related terms

Sources

  1. Planned ParenthoodWhat are the parts of the male sexual anatomy?
  2. MedlinePlusPenis Disorders