ANATOMY

Detailed explanation-1: -The thoracic wall is made up of five muscles: the external intercostal muscles, internal intercostal muscles, innermost intercostal muscles, subcostalis, and transversus thoracis. These muscles are primarily responsible for changing the volume of the thoracic cavity during respiration.

Detailed explanation-2: -Overview. The diaphragm, located below the lungs, is the major muscle of respiration. It is a large, dome-shaped muscle that contracts rhythmically and continually, and most of the time, involuntarily. Upon inhalation, the diaphragm contracts and flattens and the chest cavity enlarges.

Detailed explanation-3: -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.

Detailed explanation-4: -When the lungs inhale, the diaphragm contracts and pulls downward. At the same time, the muscles between the ribs contract and pull upward. This increases the size of the thoracic cavity and decreases the pressure inside. As a result, air rushes in and fills the lungs.

Detailed explanation-5: -To increase the volume of the lungs, the chest wall expands. This results from the contraction of the intercostal muscles, the muscles that are connected to the rib cage. Lung volume expands because the diaphragm contracts and the intercostals muscles contract, thus expanding the thoracic cavity.