Internal intercostal

Definition

The internal intercostal muscles are a group of skeletal muscles located between the ribs that assist with the process of breathing by helping to lower the rib cage and decrease the volume of the thoracic cavity during exhalation. They are found deep to the external intercostal muscles and run in a direction opposite to them.

Related terms

External Intercostal Muscles:

These are muscles located between the ribs that help elevate the ribcage, increasing thoracic volume to allow air into the lungs during inhalation.

Thoracic Cavity:

This is the chamber within the body protected by the thoracic wall, containing vital organs including lungs and heart.

Diaphragm:

A major muscle located below the lungs that plays a critical role in breathing by contracting to expand the thoracic cavity for inhalation and relaxing for exhalation