What role do intercostal muscles play during ventilation?

• A. They regulate heart rate
• B. They assist with rib cage expansion and contraction
• C. They filter the air
• D. They control blood flow in the lungs

Answer: (B)

Intercostal muscles play a crucial role during ventilation by assisting with the expansion and contraction of the rib cage. These muscles are situated between the ribs and can contract to pull the ribs upward and outward during inhalation, increasing the volume of the thoracic cavity and thereby facilitating the inflow of air into the lungs. Conversely, during exhalation, the intercostal muscles relax, allowing the ribs to return to their resting position, which helps decrease the thoracic volume and pushes air out of the lungs.

This mechanical process of movement created by the intercostal muscles is essential for effective air exchange, as it complements the diaphragm's action, which is the primary muscle involved in breathing. The coordinated efforts between the diaphragm and intercostal muscles allow for more efficient ventilation and gas exchange within the respiratory system.