Respiratory action of the intercostal muscles.

  title={Respiratory action of the intercostal muscles.},
  author={Andr{\'e} De Troyer and Peter A. Kirkwood and Theodore A. Wilson},
  journal={Physiological reviews},
  volume={85 2},
The mechanical advantages of the external and internal intercostals depend partly on the orientation of the muscle but mostly on interspace number and the position of the muscle within each interspace. Thus the external intercostals in the dorsal portion of the rostral interspaces have a large inspiratory mechanical advantage, but this advantage decreases ventrally and caudally such that in the ventral portion of the caudal interspaces, it is reversed into an expiratory mechanical advantage… 
Spatial distribution of inspiratory drive to the parasternal intercostal muscles in humans
Observations indicate that the distribution of neural drive to the parasternal intercostals in humans has a rostrocaudal gradient, but that the drive is uniform along the mediolateral extent of the second interspace.
Effect of diaphragmatic contraction on the action of the canine parasternal intercostals.
The diaphragm has no significant synergistic or antagonistic effect on the force developed by the parasternal intercostals during breathing, and this lack of effect is probably related to the constraint imposed on intercostal muscle length by the ribs and sternum.
Role of pleural pressure in the coupling between the intercostal muscles and the ribs.
Observations indicate thatDeltaPpl is a primary determinant of rib motion during intercostal muscle contraction and the decrease in DeltaPpl and the increase in inter costal muscle activity contribute equally to the increased in inspiratory cranial displacement of the ribs after diaphragm paralysis.
Mechanics of the respiratory muscles.
The mechanics of the muscles that drive expansion or contraction of the chest wall during breathing are examined, including the diaphragm, rib cage, and abdominal muscles.
Effects of unilateral airway occlusion on rib motion and inspiratory intercostal activity in dogs
It is concluded that during occlusion of a main bronchus, the increase in external intercostal activity is induced by the decrease in inspiratory cranial rib displacement in both hemithoraces, and that this decrease is determined by the increased in pleural pressure swings on both sides of the mediastinum.
Interplay between the inspiratory and postural functions of the human parasternal intercostal muscles.
Observations confirm that in addition to an inspiratory function, the parasternal intercostal muscles have a postural function, and the postural contraction of the muscles alters their output during inspiration in a direction-dependent manner.
Action of the diaphragm on the rib cage.
When the diaphragm contracts, pleural pressure falls, exerting a caudal and inward force on the entire rib cage. However, the diaphragm also exerts forces in the cranial and outward direction on the
Patterns of expiratory and inspiratory activation for thoracic motoneurones in the anaesthetized and the decerebrate rat
The nervous control of expiratory muscles is less well understood than that of the inspiratory muscles, particularly in the rat. The patterns of respiratory discharges in adult rats were therefore
Effect of intercostal muscle contraction on rib motion in humans studied by finite element analysis.
It is found that the special structure of the ventral portion of the human rib cage could be of mechanical benefit to the intercostal muscles, generating inspiratory and expiratory rib motions.


Respiratory mechanical advantage of the canine external and internal intercostal muscles
The present studies indicate that the canine external and internal intercostal muscles do not have distinct inspiratory and expiratory actions as conventionally thought, and their effects on the lung during breathing will be determined by the topographic distribution of neural drive.
Respiratory effect of the intercostal muscles in the dog.
Values of mechanical advantage and maximum respiratory effect of the intercostal muscles of the dog are reported and it is found that parasternal internal intercostals and dorsal external inter costals of the upper interspace have large inspiratory mechanical advantages and that dorsal internal inter costing of the lower interspace and triangularis sterni have large expiratory mechanical advantage.
Action of intercostal muscles on the lung in dogs.
Results indicate that when contracting in a single interspace, the external and internal intercostals have a qualitatively similar action on the lung; and this action, however, depends critically on their location along the cephalocaudal axis of the rib cage.
Respiratory effects of the external and internal intercostal muscles in humans
In the present studies, the respiratory actions of the human external and internal intercostal muscles were evaluated by applying the Maxwell reciprocity theorem and the orientation of the muscle fibres relative to the ribs and the masses of the muscles were assessed in cadavers.
Rostrocaudal gradient of mechanical advantage in the parasternal intercostal muscles of the dog.
Observations indicate that, in the dog, the rostrocaudal gradient in rib rotation induces a roStrocaudAL gradient of mechanical advantage in the parasternal intercostals, which has its climax in the second and third interspaces, and support the concept that the respiratory effect of a given respiratory muscle can be computed from its behaviour during passive inflation.
Mechanical action of the interosseous intercostal muscles as a function of lung volume.
This study assessed the action of the interosseous inter costal muscles at different lung volumes in 19 anesthetized dogs by synchronously activating the intercostal muscles via ventral root stimulation (VRS) and found EI shortened, whereas PA usually lengthened.
Linkage between parasternals and external intercostals during resting breathing.
In the dog, the inspiratory contraction of the external intercostals in the cranial portion of the rib cage is agonistic in nature as is the contraction ofThe parasternals; during resting breathing, however, the changes in length of these external inter costals are largely determined by the action of the parasternal.
Postural and ventilatory functions of intercostal muscles.
  • B. Duron
  • Medicine
    Acta neurobiologiae experimentalis
  • 1973
These results fit very well with the histological findings which disclose a much greater density of muscle spindles in external intercostals than in the diaphragm or in the interchondral muscles.
The canine parasternal and external intercostal muscles drive the ribs differently
It is established that the external intercostal muscles drive the ribs primarily in the cranial direction, whereas the parasternal intercostalsDrive the ribs both cranially and outward, and co‐ordinated activity among these two sets of muscles displaces the ribs on their relaxation curve.
Intercostal muscle compensation for parasternal paralysis in the dog: central and proprioceptive mechanisms.
The increases in external intercostal and levator costae activities that occur after inactivation of the parasternal intercostals thus result partly from the increased hypercapnic drive but mostly from proprioceptive reflexes, presumably muscle spindle reflexes.