Cough Reflex Test (CRT) Practice Exam 2025 - Free CRT Practice Questions and Study Guide

The use of accessory muscles in breathing is indicative of an increased work of breathing. When the body requires additional effort to breathe, especially during respiratory distress, it recruits accessory muscles such as those in the neck (scalene and sternocleidomastoid) and chest (pectoralis major). This response occurs because the primary muscles of breathing, like the diaphragm and intercostals, are insufficient to meet the body's respiratory demands, often due to conditions like asthma, COPD, or severe pulmonary infections.

In normal respiratory function, the diaphragm and intercostal muscles operate effectively without the need for accessory muscle involvement. A decrease in oxygen demand typically leads to relaxed and efficient breathing patterns, without reliance on these additional muscle groups. Similarly, effective diaphragm contraction is characterized by a smooth and adequate breathing pattern, not the recruitment of accessory muscles. Thus, the presence of accessory muscle usage highlights increased respiratory effort and often points to underlying respiratory challenges.