In the context of ventilation, what is the primary purpose of the intercostal muscles?

• A. Regulating body temperature
• B. Facilitating gas exchange
• C. Supporting thoracic wall stability
• D. Changing thoracic volume during breathing

Answer: (D)

The primary purpose of the intercostal muscles is to change thoracic volume during breathing. These muscles are located between the ribs and play a crucial role in the mechanics of ventilation. During inhalation, the intercostal muscles contract, which elevates the ribs and expands the thoracic cavity. This expansion decreases the pressure within the thoracic cavity, allowing air to flow into the lungs. Conversely, during exhalation, the intercostal muscles relax, helping to decrease the volume of the thoracic cavity and pushing air out of the lungs.

In this context, the intercostal muscles are essential for the process of ventilation, as they directly influence the changes in thoracic volume that are necessary for inhaling and exhaling air. While supporting thoracic wall stability and facilitating gas exchange are important functions in the respiratory system, they are not the primary roles of the intercostal muscles themselves. Regulating body temperature does not pertain to the intercostal muscles' functions in breathing either.