What role do accessory muscles play in respiration?

Accessory muscles are recruited primarily during periods of increased respiratory demand, such as heavy exertion or when a person is experiencing respiratory distress. These muscles, including the sternocleidomastoid and scalene muscles in the neck, as well as the pectoralis major and minor in the chest, help to expand the thoracic cavity beyond the normal action of the diaphragm and intercostal muscles.

In situations where the body needs more oxygen or experiences difficulty in breathing, these muscles become actively engaged to increase the volume of air that can be inhaled and facilitate respiration. Their role is particularly crucial during intense physical activity or conditions like asthma, pneumonia, or chronic obstructive pulmonary disease (COPD), where the primary muscles of respiration alone may not suffice to meet the oxygen demands of the body.

Understanding the role of these accessory muscles is important for recognizing how the body adapts to increased respiratory challenges and for assessing respiratory function in clinical settings.