GENERAL HISTOLOGY

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: -In exhalation the interosseous portions of the internal intercostal muscles, (the part of the muscle that is between the bone portion of the superior and inferior ribs), depresses and retracts the ribs, compressing the thoracic cavity and expelling air.

Detailed explanation-3: -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-4: -Primary Muscles Relaxed normal expiration is a passive process, happens because of the elastic recoil of the lungs and surface tension. However there are a few muscles that help in forceful expiration and include the internal intercostals, intercostalis intimi, subcostals and the abdominal muscles.

Detailed explanation-5: -When you exhale: the intercostal muscles relax pulling the ribcage downwards and inwards. the diaphragm relaxes, doming upwards. volume of the thorax decreases and the pressure inside increases.