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July 27, 2026Sources cited
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Penis

The penis is an external male sex organ that is part of the urinary and reproductive systems.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 27, 2026|2 min read| Fact-checked

The penis is an external male sex organ that is part of the urinary and reproductive systems. It is used for urination, sexual activity, and ejaculation, and it contains erectile tissue, blood vessels, nerves, and the urethra. In human anatomy, it is typically described by the root, shaft/body, and glans.

Anatomy

The penis is commonly divided into the root, body or shaft, and glans. Its internal structure is made of erectile tissues, with the paired corpora cavernosa on top and the corpus spongiosum surrounding the urethra.

Function

The penis serves as a route for urine to leave the body and for semen to be expelled during ejaculation. It also plays a role in sexual arousal, intercourse, and orgasm.

Blood supply and erection

During erection, blood fills the erectile tissues and makes the penis firm. This process depends on the penile blood vessels and nerve signalling that regulate blood flow.

Development and variation

Penises vary in size, shape, circumcision status, and appearance among individuals. Medical sources note that average size measurements differ between flaccid and erect states, and normal variation is broad.

Key facts

  • The penis is an external organ involved in both urination and reproduction.
  • It contains three erectile cylinders: two corpora cavernosa and one corpus spongiosum.
  • The urethra passes through the penis and opens at the tip of the glans.
  • The glans is the distal, enlarged end of the penis and is highly sensitive.
  • The penis is innervated by sensory, motor, sympathetic, and parasympathetic nerves.
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Canadian context

Canadian medical and educational sources commonly teach penis anatomy as part of human reproductive and urinary system education.

Frequently asked questions

What is the penis?
The penis is an external male sex organ that belongs to both the urinary and reproductive systems.
What are the main parts of the penis?
The main parts are the root, body or shaft, and glans.
What is the urethra’s role in the penis?
The urethra runs through the penis and carries urine and semen to the external opening at the tip.
What tissues make up the penis?
It contains erectile tissue, mainly the paired corpora cavernosa and the corpus spongiosum.
What does the penis do?
Its main functions are urination, sexual activity, and ejaculation.
Is penis size the same for everyone?
No. Penis size and shape vary widely among individuals, and medical sources describe a broad range of normal variation.

References

  1. Cleveland Clinic — https://my.clevelandclinic.org/health/body/penis
    Supports: Anatomy, function, erectile tissue, average erect length, location
  2. TeachMeAnatomy — https://teachmeanatomy.info/pelvis/the-male-reproductive-system/penis/
    Supports: Root, body, glans, erectile tissues, external urethral orifice
  3. NCBI Bookshelf (StatPearls) — https://www.ncbi.nlm.nih.gov/books/NBK482236/
    Supports: Three parts of the penis and main functions
  4. Encyclopaedia Britannica — https://www.britannica.com/science/penis
    Supports: General definition and role as copulatory organ and urine channel
  5. SEER Training Modules — https://training.seer.cancer.gov/anatomy/reproductive/male/penis.html
    Supports: Penis structure, erectile tissues, urethra, foreskin