Relationship between neural drive and mechanical effect in the respiratory system.
The actions of the canine external and internal interosseous intercostal muscles on the lung were assessed by applying the Maxwell reciprocity theorem. The external intercostals in the dorsal part of the cranial interspaces were found to have a large inspiratory effect. However, this effect decreases continuously in the caudal and the ventral direction, such that the muscles in the ventral part of the caudal interspaces have an expiratory effect. The internal intercostals also show marked gradients, such that the muscles in the dorsal part of the caudal interspaces have a large expiratory effect and those in the ventral part of the most cranial interspaces have a small inspiratory effect. During breathing, however, inspiratory activity is found only in the external intercostals with an inspiratory effect, and expiratory activity is confined to the internal intercostals with an expiratory effect. The spatial distribution of inspiratory activity among the canine external intercostals closely mirrors the distribution of inspiratory effect, and the distribution of expiratory activity among the internal intercostals closely mirrors the distribution of expiratory effect. Therefore, the external intercostals have a clear-cut inspiratory action on the lung during breathing, whereas the internal intercostals have a definite expiratory action. The distribution of neural drive among these muscles appears to be equally well matched to the distribution of respiratory effect in humans.
De Troyer
André
A
Laboratory of Cardiorespiratory Physiology, Brussels School of Medicine, and Erasme University Hospital, Belgium. a_detroyer@yahoo.fr
D000818:Animals; D006801:Humans; D007366:Intercostal Muscles / Q000502:physiology; D009424:Nervous System Physiological Phenomena; D015656:Respiratory Mechanics; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000294:innervation*