The diaphragm muscle is the princip...

The diaphragm muscle is the principal muscle of inspiration, contributing between 66% and 75% of the tidal turn depending on the position of the individual. However, the intercostal muscles also make a significant contribution to inspiration. It has been generally assumed that the external intercostals contribute to inspiration while the internal intercostals contribute to forced expiration. The external intercostals were assumed to be inspiratory muscles as they acted upon the ribs by elevating them. The internal intercostals were assumed to be expiratory muscles as they acted forward the ribs by depressing them. DiMarco et al (1990) set that both me internal intercostals and the external intercostals are active during inspiration and the external intercostals are active during forced expiration. Since publication of this reflection there has not been an adequate explanation of the part of the internal intercostals and the external intercostals during breathing. The intention of this presentation is to provide a possible explanation of the part these muscles play during inspiration and expiration. In addition, pair other possible theories will be currented how the intercostals function for patients with pathologies. These explanations, based upon recent reviews of the literature and basic biomechanical principles, and may provide a better understanding of the kinesiology of the intercostals during breathing.

J Roush1, D Madras'. 1Physical Therapy Program, Arizona gymnasium of Health Sciences, Mesa AZ, Thysical Therapy Program, guild Misericordia, Dallas, PA.

Copyright Cardiopulmonary Physical Therapy Journal Dec 2003

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