MICROANATOMY

Detailed explanation-1: -The rib cage muscles, including the intercostals, the parasternals, the scalene and the neck muscles, mostly act on the upper part of the rib cage (pulmonary rib cage) and are both inspiratory and expiratory. The abdominal muscles act on the abdomen and the abdominal rib cage and are expiratory.

Detailed explanation-2: -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-3: -Internal intercostal muscles are the accessory respiratory muscles. Together with innermost intercostals, they enable forced expiration by depressing the ribs, thus shrinking the diameter of the thoracic cavity and pushing the air out of the lungs.

Detailed explanation-4: -The intercostal muscles relax while the lungs are expanding, allowing them to fill up with air. When an organism breathes out, the intercostal muscles contract to put pressure on the lungs and help drive the air out.

Detailed explanation-5: -In quiet expiration the diaphragm relaxes and lung tissue recoils resulting in the expulsion of air. During active or forced expiration a number of muscles may be recruited: Internal intercostals (interosseous component) Muscles of the abdominal wall.