Internal intercostals
Chest
Deep muscle — it lies under other muscles. X-ray makes the muscles over it see-through.
- Origin
- Ridge on the inner surface of each rib and its costal cartilage
- Insertion
- Upper border of the rib below
- Action
- Pull the ribs together, mainly in forced breathing out
- Nerve supply
- Intercostal nerves (T1–T11)
The layer just under the external intercostals, with fibres running at right angles to them. They work mainly in forceful breathing out, as in coughing or blowing hard.
Internal intercostals anatomy page →