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Internal intercostal muscle: anatomy, location and function

The middle layer of intercostal muscles. Depresses the ribs during forced expiration and holds the intercostal space firm.

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Highlighted in the model: Internal intercostal muscle. Click any part to read about it, or switch off “Highlight topic” to see the whole body. 3D data: BodyParts3D, © The Database Center for Life Science, CC BY 4.0; meshes simplified and recoloured. The model is an adult male.

Internal intercostal muscle at a glance

What it is
The middle layer of intercostal muscles.
Location
Runs from the costal groove and lower border of each rib to the upper border of the rib below, with fibres directed downward and backward.
Function
Depresses the ribs during forced expiration and holds the intercostal space firm.
Body system
Muscular · single, midline structure
FMA ID
FMA9757 (Foundational Model of Anatomy)

Key facts

  • Innervation: intercostal nerves (T1–T11)
  • Blood supply: posterior and anterior intercostal arteries

Structures next to the internal intercostal muscle

The nearest named structures in the 3D model, measured from the centre of each part:

References

  1. Foundational Model of Anatomy: Internal intercostal muscle (FMA9757). EMBL-EBI Ontology Lookup Service.
  2. OpenStax. Anatomy and Physiology 2e, §11.2 Naming Skeletal Muscles. Rice University, 2022.
  3. Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.

Related anatomy

Explore the whole body in the interactive 3D human anatomy model, or browse the A–Z list of human structures.