What is the diaphragm (in breathing)?

The the diaphragm is called the diaphragm. Gray's Anatomy (1918) describes it as a dome-shaped sheet of muscle and tendon.

What it is

  • A dome-shaped sheet of muscle and tendon.
  • The principal muscle of breathing.
  • When it contracts and flattens, air is drawn into the lungs.

Where it is

  • Between the chest cavity and the abdominal cavity.
  • Attached to the lower ribs, sternum, and lumbar vertebrae.
  • Pierced by the esophagus, aorta, and inferior vena cava.

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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