| Abstract: | Boriek, Aladin M., Joseph R. Rodarte, and Theodore A. Wilson. Kinematics and mechanics of midcostal diaphragm of dog. J. Appl. Physiol. 83(4):1068-1075, 1997. Radiopaque markers were attached to theperitoneal surface of three neighboring muscle bundles in the midcostaldiaphragm of four dogs, and the locations of the markers were trackedby biplanar video fluoroscopy during quiet spontaneous breathing andduring inspiratory efforts against an occluded airway at three lungvolumes from functional residual capacity to total lung capacity inboth the prone and supine postures. Length and curvature of the musclebundles were determined from the data on marker location. Musclelengths for the inspiratory states, as a fraction of length atfunctional residual capacity, ranged from 0.89 ± 0.04 at endinspiration during spontaneous breathing down to 0.68 ± 0.07 duringinspiratory efforts at total lung capacity. The muscle bundles werefound to have the shape of circular arcs, with the three bundlesforming a section of a right circular cylinder. With increasing lungvolume and diaphragm displacement, the circular arcs rotate around theline of insertion on the chest wall, the arcs shorten, but the radiusof curvature remains nearly constant. Maximal transdiaphragmaticpressure was calculated from muscle curvature and maximaltension-length data from the literature. The calculated maximaltransdiaphragmatic pressure-length curve agrees well with the data ofRoad et al. (J. Appl. Physiol. 60:63-67, 1986). |
