NEET BIOLOGY

Detailed explanation-1: -During expiration, the internal intercostal muscles contract, and the diaphragm relaxes. This is because the internal intercostal muscles contracting and the diaphragm relaxing decreases the volume of the thoracic cavity. This in turn decreases the volume of the lungs.

Detailed explanation-2: -The external intercostal muscles have an inspiratory action on the rib cage, whereas the internal intercostal muscles are expiratory.

Detailed explanation-3: -Contraction of the internal intercostal muscles decreases the anteroposterior diameter of the thorax, aiding in expiration. The abdominal muscles aid in forceful expiration (such as coughing) by increasing intraabdominal pressure; the increased pressure is transmitted through the diaphragm to the pleural space.

Detailed explanation-4: -The major muscle group for exhalation is made up of the internal intercostals. These muscles pull down on the rib cage and thereby push air out of the lungs.

Detailed explanation-5: -The intercostal muscles are the muscles between the ribs. During breathing, these muscles normally tighten and pull the rib cage up. Your chest expands and the lungs fill with air. Intercostal retractions are due to reduced air pressure inside your chest.