What is the thymus?

It is called the thymus. Gray's Anatomy (1918) describes it as a soft, lobed lymphoid organ.

What it is

  • A soft, lobed lymphoid organ.
  • Prominent in children and adolescents; shrinks after puberty.
  • Where T-lymphocytes mature.

Where it is

  • In the upper chest, behind the sternum.
  • In front of the great vessels and the heart.
  • Extends up into the lower neck in children.

Source:

Last verified: 2026-07-18

  • Best Anatomy Answers is an educational reference about human anatomy. It is not medical advice — for any health concern, talk to a licensed medical professional.

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