Muscles: Internal Intercostals.

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Anatomy & Physiology: Muscles—Internal Intercostals.

Structure.

• Origin: superior border of rib below.
• Insertion: inferior border of rib above.

Function.

• Concentric action: draws adjacent ribs together to decrease anteroposterior and lateral dimensions of thoracic cavity (forced exhalation); ipsilateral trunk rotation. Lesser: trunk flexion, lateral flexion, and extension.
• Reverse mover action: elevate ribs 2-12; trunk contralateral rotation, flexion, lateral flexion, and extension.
• Eccentric action: control/restrain/slows rib 1-11 elevation and depression; trunk contralateral rotation and ipsilateral rotation; flexion, extension, and contralateral lateral flexion of trunk.
• Isometric action: stabilization of ribs and spine.
• Innervation: thoracic nerve T2-T12.
• Arterial supply: anterior intercostal arteries, posterior intercostal arteries, costocervical trunk and superior thoracic artery.

Clinical Significance.

More.

• https://www.youtube.com/watch?v=0Fw5ibdD6d4
• https://www.youtube.com/watch?v=NwDxbNqEVaA

Internal intercostals. Used with permission by 3D4Medical.

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Cedars-Sinai. (2018). Vertebrae of the spine. Retrieved from https://www.cedars-sinai.org/health-library/diseases-and-conditions/v/vertebrae-of-the-spine.html

Clark, M., Lucett, S., Sutton, B. G., & National Academy of Sports Medicine. (2014). NASM essentials of corrective exercise training. Burlington, MA: Jones & Bartlett Learning.

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.