What does the external intercostal muscle assist with?

What does the external intercostal muscle assist with?

• A. Expiration
• B. Inspiration
• C. Forced expiration
• D. Respiratory cycle regulation

Answer: (B)

The external intercostal muscles play a crucial role in the mechanics of breathing, particularly during inspiration. These muscles are situated between the ribs and, when they contract, they elevate the rib cage, which increases thoracic volume. This expansion of the thoracic cavity allows air to be drawn into the lungs, facilitating the process of inhalation. During normal, relaxed breathing, the primary action needed for inspiration is the contraction of the external intercostal muscles along with the diaphragm, which also contracts and moves downward. This coordinated action decreases the pressure within the thoracic cavity relative to atmospheric pressure, enabling air to flow into the lungs. In contrast, the other choices relate to different aspects of breathing mechanics. Expiration is primarily a passive process during restful breathing, relying on the relaxation of the diaphragm and external intercostal muscles, though it can become active during forced expiration when other muscle groups, like the internal intercostals and abdominal muscles, engage. Respiratory cycle regulation involves complex neural control mechanisms, which do not directly pertain to the specific muscular actions of the external intercostals. Thus, the role of the external intercostal muscles is specifically aligned with aiding the process of inspiration.

The external intercostal muscles play a crucial role in the mechanics of breathing, particularly during inspiration. These muscles are situated between the ribs and, when they contract, they elevate the rib cage, which increases thoracic volume. This expansion of the thoracic cavity allows air to be drawn into the lungs, facilitating the process of inhalation.

During normal, relaxed breathing, the primary action needed for inspiration is the contraction of the external intercostal muscles along with the diaphragm, which also contracts and moves downward. This coordinated action decreases the pressure within the thoracic cavity relative to atmospheric pressure, enabling air to flow into the lungs.

In contrast, the other choices relate to different aspects of breathing mechanics. Expiration is primarily a passive process during restful breathing, relying on the relaxation of the diaphragm and external intercostal muscles, though it can become active during forced expiration when other muscle groups, like the internal intercostals and abdominal muscles, engage. Respiratory cycle regulation involves complex neural control mechanisms, which do not directly pertain to the specific muscular actions of the external intercostals. Thus, the role of the external intercostal muscles is specifically aligned with aiding the process of inspiration.