Joe Muscolino

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The subcostales are seen bilaterally. The internal abdominal oblique is ghosted in on the left side.

  • The subcostales attach from ribs #10-12 to ribs #8-10.



  • Depress ribs #8-10 at the sternocostal and costospinal joints.
  • Elevate ribs #10-12 at the sternocostal and costospinal joints.



  1. The subcostales are located internally within the thoracic cavity.
  2. Generally muscles that depress ribs act to create expiration.
  3. Generally, muscles that elevate ribs act to create inspiration.
  4. Sometimes, a muscle that depresses lower ribs can facilitate inspiration by stabilizing the lower ribs against the upward pull of the diaphragm, thereby assisting the diaphragm’s dome to drop (increasing the vertical diameter of the thoracic cavity to allow for expansion of the lungs), thereby acting to assist with inspiration.