What is the significance of the accessory muscles in respiration?

The accessory muscles of respiration play a crucial role during periods of increased respiratory demand, such as during forced breathing or when a patient is experiencing respiratory distress. Normally, the primary muscles of respiration include the diaphragm and the intercostal muscles. However, when these muscles are insufficient to meet the body's increased oxygen needs or to expel carbon dioxide, the accessory muscles become engaged.

These accessory muscles, which include the sternocleidomastoid, scalene muscles, and pectoralis major, provide additional force and help expand the thoracic cavity more significantly. This is particularly important in situations like asthma attacks, severe pneumonia, or other conditions causing difficulty in breathing, where the body requires more vigorous inhalation and exhalation.

Utilizing these muscles allows for greater lung expansion and increased airflow, ensuring adequate gas exchange can still occur despite the compromised respiratory system. Therefore, in clinical practice, recognizing the use of accessory muscles is an important indicator of respiratory distress and the need for intervention.