What physiological role do the intercostal muscles play?

The intercostal muscles, located between the ribs, are crucial for the process of breathing. When these muscles contract, they elevate the ribs and expand the rib cage, which creates a negative pressure within the thoracic cavity. This negative pressure allows air to flow into the lungs, facilitating inhalation. Conversely, when the intercostal muscles relax, the rib cage decreases in size, which helps push air out of the lungs during exhalation. This back-and-forth movement is vital for the respiratory cycle and highlights the important role these muscles play in respiration.