Chest · Skeletal muscle
Diaphragm (Breathing Muscle)
The diaphragm is the dome-shaped muscle under the lungs that powers breathing. It flattens to pull air in and relaxes to push it out — automatically, around the clock.
What it is
The diaphragm is a large, thin, dome-shaped sheet of muscle separating the chest from the abdomen.
Where it is
Beneath the lungs and heart, forming the floor of the chest cavity.
What it does
Contracts and flattens to draw air into the lungs (breathing in), then relaxes to help push air out.
Everyday use
Every breath you take, as well as coughing, sneezing and straining, involves the diaphragm.
When things go wrong
Common problems affecting the diaphragm (breathing muscle)
- Hiatus hernia (part of the stomach pushing through the diaphragm)
- Hiccups (sudden diaphragm spasms)
- Diaphragm weakness affecting breathing
Education and reference only. This explains the anatomy in plain terms and is not a diagnosis. Sudden severe symptoms — such as crushing chest pain or collapse — are an emergency; call 999.
Looking after it
Keeping it healthy
Breathing exercises can strengthen and relax the diaphragm; most diaphragm problems are managed by treating the underlying cause.
Did you know?
An interesting fact
A hiccup is a sudden involuntary spasm of the diaphragm, followed by the quick closing of the vocal cords that makes the "hic" sound.
Answers
Diaphragm (Breathing Muscle): frequently asked questions
What does the diaphragm do?
The diaphragm is the main breathing muscle. It flattens to pull air into the lungs and relaxes to let it out, working automatically day and night.
What causes hiccups?
Hiccups are sudden spasms of the diaphragm. They are usually harmless and brief; hiccups lasting more than a couple of days should be checked by a doctor.
Related muscles
Explore the chest
Sources
Where this is drawn from
- NHS — Muscles and movement
- Gray's Anatomy for Students
- TeachMeAnatomy — muscular system
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