PATHOLOGY

Detailed explanation-1: -During quiet breathing at rest, expiration is passive, air leaving the lungs principally as a result of the relaxation of the inspiratory striated muscles of breathing and elastic recoil of the lungs.

Detailed explanation-2: -Expiration. In healthy people quiet expiration or exhalation is passive and relies on elastic recoil of the stretched lungs as the inspiratory muscles relax, rather than on muscle contraction.

Detailed explanation-3: -Respiratory movements during quiet breathing are described first. The muscles that contribute to quiet breathing are the external intercostal muscles and the diaphragm. (The external and internal intercostals are the muscles that fill the gaps between the ribs.)