Muscle
Internal intercostals
Depress ribs (expiration)
High-yield
Fibres perpendicular to external intercostals; depress ribs in forced expiration. Intercostal nerves.
Overview
Muscles deep to the external intercostals whose fibres run perpendicularly; their interosseous parts depress the ribs during forced expiration.
Reference facts
- Origin
- Superior border of the rib below (medial to the costal angle)
- Insertion
- Inferior border of the rib above
- Action
- Depress the ribs in forced expiration; the interchondral part aids inspiration
- Innervation
- Intercostal nerves (anterior rami of T1-T11)
- Blood supply
- Posterior and anterior intercostal arteries
Frequently asked questions
What does the internal intercostals do?
The internal intercostals depress the ribs in forced expiration; the interchondral part aids inspiration.
What nerve innervates the internal intercostals?
The internal intercostals is innervated by the intercostal nerves (anterior rami of T1-T11).
Where does the internal intercostals attach?
The internal intercostals originates from the superior border of the rib below (medial to the costal angle) and inserts on the inferior border of the rib above.
What is the blood supply of the internal intercostals?
The internal intercostals is supplied by the posterior and anterior intercostal arteries.