A model of inspiratory muscle mechanics

We have previously shown that the costal and crural parts of the diaphragm have different actions on the rib cage (RC) and that the tension developed in one part is not transmitted perfectly to the other. Thus the diaphragm can be modeled pneumatically or electrically as two generators or pumps in s...

Full description

Saved in:
Bibliographic Details
Published inJournal of applied physiology: respiratory, environmental and exercise physiology Vol. 55; no. 2; p. 547
Main Authors Macklem, P T, Macklem, D M, De Troyer, A
Format Journal Article
LanguageEnglish
Published United States 01.08.1983
Subjects
Biomechanical Phenomena
Diaphragm - physiology
Humans
Intercostal Muscles - physiology
Models, Biological
Pleura - physiology
Pressure
Respiration
Online AccessGet more information

Cover

More Information
Summary:We have previously shown that the costal and crural parts of the diaphragm have different actions on the rib cage (RC) and that the tension developed in one part is not transmitted perfectly to the other. Thus the diaphragm can be modeled pneumatically or electrically as two generators or pumps in series between the lung and abdomen. As such, the force developed by diaphragmatic contraction is the sum of the forces developed in each part, whereas the volume displaced is the same for each part and equal to the total volume displaced. The costal part of the diaphragm is in series with the intercostal and accessory (IA) muscles between the lung and RC, whereas the crural part is in parallel. The volume displaced by simultaneous contraction of the crural part and IA is the sum of volumes displaced by each part. The action of pleural and abdominal pressure [acting through the area of apposition (Aap) of the diaphragm to RC] can be modelled as a summing junction between IA and RC. With hyperinflation the costal part acts more and more in parallel with both IA and the crural part, whereas Aap diminishes, so that the ability to develop large forces decreases independently of the muscles' force-length relationships. The model also predicts that the factors determining the length of the costal and crural parts are different. Finally, the parallel and serial arrangement of the inspiratory musculature allows for increases in maximum power, maximum force, and maximum velocity by appropriate recruitment of the various muscle groups.
ISSN:0161-7567
2691-2465
DOI:10.1152/jappl.1983.55.2.547