[Special characteristics of the diaphragm muscle cell]

The diaphragm is the main inspiratory muscle, accounting for more than 50% of the tidal volume during quiet breathing. It works continuously, contracting rhythmically and generally at a low intensity. In this respect, it is close to the myocardium, being the only vital skeletal muscle. From a general point of view, functional and biochemical characteristics of the diaphragm are similar to those of other skeletal muscles with a similar fiber type composition. However, the diaphragm presents some specificities allowing a high supply of metabolic substrates. This could serve to preserve contractile function in different physiological and physiopathological situations. Such specificities concern muscular vascularization, the microvascular network and the content of mitochondria and myoglobin. These characteristics are detailed and compared to those of other striated muscles.