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AnatomyBasicsFirst look at bones and muscles
Intercostal muscles

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Intercostal muscles

Last reviewed: December 22, 2019

The intercostal muscles are a group of intrinsic chest wall muscles occupying the intercostal spaces. They play an important role for the breathing mechanism. This article covers their origins and insertions, supply, function and clinical aspects.

Contents
  1. Anatomy
  2. Function
  3. Clinical aspects
  4. Related diagrams and images
+ Show all

Anatomy

The intercostal muscles consist of:

  • External intercostal muscles: course from the inferior border of a rib inferoanteriorly to the superior border of the rib below. Anteriorly they are bordered by the external thoracic fascia.
  • Internal intercostal muscles: originate at the costal groove/inferior border of a rib, with it's fibres running inferoposteriorly to the superior border of the rib above.
  • Innermost intercostal muscles: separate from the internal intercostal muscles, they extend from the medial edge of the costal groove to the medial surface of the rib below. Inwards they are bordered by the internal thoracic fascia.

The fibrous space between the internal and innermost intercostal muscles and the lower border of the rib above forms the intercostal tunnel. This tunnel provides passage for the intercostal artery, vein and nerve.

They are supplied by the intercostal nerves which arise from the thoracic nerves (T1-11) and run in the costal grooves along with the intercostal vessels.

Function

Recommended video: Intercostal muscles
Attachments, innervation and functions of the intercostal muscles.

The task of the intercostal muscles is to tense the intercostal spaces during deep inspiration and support the breathing mechanism. The contraction of the external intercostal muscles causes an elevation of the ribs (inspiratory breathing muscles) whereas both the internal and innermost intercostal muscles lower the ribs (expiratory breathing muscles).

Clinical aspects

Deficient intercostal muscles (e.g. caused by neuromuscular diseases) may not provide an appropriate tension of the intercostal spaces anymore leading to internal and external movements of the chest wall during thoracic pressure changes. Consequently this will lead to respiratory insufficiency. The lesion of a single intercostal nerve (e.g. after trauma or surgical procedures) causes a “strip-like” paresthesia. However in this case motor impairments are absent.

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Show references

References:

  • D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, 1.Auflage, Urban & Fischer Verlag/Elsevier (2008), S.149, 167
  • M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2.Auflage, Thieme Verlag (2007), S.156
  • R. Putz/R. Pabst: Sobotta – Anatomie des Menschen, 22.Auflage, Urban & Fischer Verlag/Elsevier (2007), S.312-313
  • W. Graumann/ D.Sasse: CompactLehrbuch der gesamten Anatomie – Band 2 – Bewegungsapparat, Schattauer Verlag (2003), S.57-60
  • Peter Berlit: Klinische Neurologie, 3.Auflage, Springer Verlag (2011), S.353-354

Author and layout:

  • Achudhan Karunaharamoorthy
  • Christopher A. Becker

Illustrators:

  • External intercostal muscles (ventral view) - Yousun Koh
  • Internal intercostal muscles (ventral view) - Yousun Koh
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

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