MuscleThoracic wall
External intercostals
Latin: Mm. intercostales externi
Location: Thorax
View the external intercostals in 3DOrigin
Inferior border of each rib, running downward and forward.
Insertion
Superior border of the rib below.
Action
Elevate the ribs in inspiration — with the diaphragm's partner expanding the cage's volume.
Nerve supply
Intercostal nerves (corresponding thoracic rami).
Blood supply
Posterior intercostal arteries.
Clinical relevance
The intercostal neurovascular bundle runs deeper, between the internal and innermost layers; chest drains pass just above a rib to avoid the bundle in the costal groove of the rib above.
Educational anatomy reference, not medical advice. About this content.