HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wilson, T. A. Articles by Troyer, A. D. Search for Related Content PubMed PubMed Citation Articles by Wilson, T. A. Articles by Troyer, A. D.

Respiratory effects of the external and internal intercostal muscles in humans

Theodore A. Wilson*, Alexandre Legrand†‡, Pierre-Alain Gevenois§ and André De Troyer†‡

1. The current conventional view of intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external intercostals have an inspiratory action on the lung and the internal interosseous intercostals have an expiratory action. Recent studies in dogs, however, have shown that this notion is only approximate.

2. In the present studies, the respiratory actions of the human external and internal intercostal muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the orientation of the muscle fibres relative to the ribs and the masses of the muscles were first assessed in cadavers. Five healthy individuals were then placed in a computed tomographic scanner to determine the geometry of the ribs and their precise transformation during passive inflation to total lung capacity. The fractional changes in length of lines with the orientation of the muscle fibres were then computed to obtain the mechanical advantages of the muscles. These values were finally multiplied by muscle mass and maximum active stress (3·0 kg cm^-2) to evaluate the potential effects of the muscles on the lung.

3. The external intercostal in the dorsal half of the second interspace was found to have a large inspiratory effect. However, this effect decreases rapidly in the caudal direction, in particular in the ventral portion of the ribcage. As a result, it is reversed into an expiratory effect in the ventral half of the sixth and eighth interspaces.

4. The internal intercostals in the ventral half of the sixth and eighth interspaces have a large expiratory effect, but this effect decreases dorsally and cranially.

5. The total pressure generated by all the external intercostals during a maximum contraction would be -15 cmH₂O, and that generated by all the internal interosseous intercostals would be +40 cmH₂O. These pressure changes are substantially greater than those induced by the parasternal intercostal and triangularis sterni muscles, respectively.

This article has been cited by other articles:

				J. E. Butler and S. C. Gandevia The output from human inspiratory motoneurone pools J. Physiol., March 1, 2008; 586(5): 1257 - 1264. [Abstract] [Full Text] [PDF]

				F. Bellemare and A. Jeanneret Sex differences in thoracic adaptation to pulmonary hyperinflation in cystic fibrosis Eur. Respir. J., January 1, 2007; 29(1): 98 - 107. [Abstract] [Full Text] [PDF]

				S. C. Gandevia, A. L. Hudson, R. B. Gorman, J. E. Butler, and A. De Troyer Spatial distribution of inspiratory drive to the parasternal intercostal muscles in humans J. Physiol., May 15, 2006; 573(1): 263 - 275. [Abstract] [Full Text] [PDF]

				D. Leduc and A. D. Troyer The effect of lung inflation on the inspiratory action of the canine parasternal intercostals J Appl Physiol, March 1, 2006; 100(3): 858 - 863. [Abstract] [Full Text] [PDF]

				A. De Troyer, P. A. Kirkwood, and T. A. Wilson Respiratory Action of the Intercostal Muscles Physiol Rev, April 1, 2005; 85(2): 717 - 756. [Abstract] [Full Text] [PDF]

				A. De Troyer and D. Leduc Effects of inflation on the coupling between the ribs and the lung in dogs J. Physiol., March 1, 2004; 555(2): 481 - 488. [Abstract] [Full Text] [PDF]

				T. A. Wilson and A. De Troyer The two mechanisms of intercostal muscle action on the lung J Appl Physiol, February 1, 2004; 96(2): 483 - 488. [Abstract] [Full Text] [PDF]

				M. Orozco-Levi Structure and function of the respiratory muscles in patients with COPD: impairment or adaptation? Eur. Respir. J., November 2, 2003; 22(46_suppl): 41S - 51s. [Abstract] [Full Text] [PDF]

				F. Bellemare, A. Jeanneret, and J. Couture Sex Differences in Thoracic Dimensions and Configuration Am. J. Respir. Crit. Care Med., August 1, 2003; 168(3): 305 - 312. [Abstract] [Full Text] [PDF]

				F. Laghi and M. J. Tobin Disorders of the Respiratory Muscles Am. J. Respir. Crit. Care Med., July 1, 2003; 168(1): 10 - 48. [Abstract] [Full Text] [PDF]

				A. De Troyer, M. Cappello, N. Meurant, and P. Scillia Synergism between the canine left and right hemidiaphragms J Appl Physiol, May 1, 2003; 94(5): 1757 - 1765. [Abstract] [Full Text] [PDF]

				A. Legrand, E. Schneider, P.-A. Gevenois, and A. De Troyer Respiratory effects of the scalene and sternomastoid muscles in humans J Appl Physiol, April 1, 2003; 94(4): 1467 - 1472. [Abstract] [Full Text] [PDF]

				F. Ribera, B. N'Guessan, J. Zoll, D. Fortin, B. Serrurier, B. Mettauer, X. Bigard, R. Ventura-Clapier, and E. Lampert Mitochondrial Electron Transport Chain Function Is Enhanced in Inspiratory Muscles of Patients with Chronic Obstructive Pulmonary Disease Am. J. Respir. Crit. Care Med., March 15, 2003; 167(6): 873 - 879. [Abstract] [Full Text] [PDF]