Accessory muscles of respiration

Last revised by Daniel J Bell on 23 Jul 2022

Accessory muscles of respiration refer to muscles that provide assistance to the main breathing muscles, mainly when additional power is needed, for example during exercise or those with airway pathologies (e.g. COPD) 1,2.

During normal quiet breathing, inspiration is an active process primarily due to the action of the diaphragm, with contributions from abdominal and external intercostal muscles 2.

Conversely, expiration is a passive process as a consequence of the elastic recoil of the rib cage and associated structures 2.

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