Striated respiratory muscles are necessary for lung ventilation and to maintain the patency of
the upper airway. The basic structural and functional properties of respiratory muscles are
similar to those of other striated muscles (both skeletal and cardiac). The sarcomere is the
fundamental organizational unit of striated muscles and sarcomeric proteins underlie the
passive and active mechanical properties of muscle fibers. In this respect, the functional
categorization of different fiber types provides a conceptual framework to understand the …

We examined the in-vitro mechanical characteristics of the diaphragm and parasternal
intercostal muscles in adult baboons. At optimal length (L 0) the parasternal intercostal
muscles were consistently faster than the diaphragm as judged by a shorter time-to-peak
tension and a reduced twitch-to-tetanus ratio. However, maximal absolute force at L 0,
correlated for cross-sectional area, revealed that the inherent strengths of both inspiratory
muscles were identical (31.5±3.2 N/cm 2 for diaphragm vs 29.5±1.1 N/cm 2 for parasternal …