# What are the intercostal muscles?

The muscles between the ribs is called the intercostal muscles. Gray's Anatomy (1918) describes it as two layers of thin muscles — external and internal intercostals — filling the spaces between adjacent ribs.

## What it means

- Two layers of thin muscles — external and internal intercostals — filling the spaces between adjacent ribs.
- Elevate and depress the ribs during breathing.
- Help stiffen the chest wall.

## Action steps

1. Between each pair of ribs, on both sides of the chest.
2. Extend from the vertebral column behind to the sternum in front.
3. Run in different directions in each layer.

## Sources

- [Gray's Anatomy of the Human Body (1918)](https://www.bartleby.com/107/)

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