ANATOMY

Detailed explanation-1: -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-2: -So, the correct answer is ‘Contracts and flattens’.

Detailed explanation-3: -As the diaphragm contracts, the volume of the thoracic cavity increases, creating a negative pressure there, which draws air into the lungs. Hence, Option A is correct.

Detailed explanation-4: -Complete answer: Option: A – The diaphragm and external intercostal muscles contract during inspiration to allow air to enter the lungs, which necessitates the contraction of numerous muscles; the diaphragm and external intercostal muscles contract. Thus, Option A is correct.

Detailed explanation-5: -During inhalation, the diaphragm contracts and moves downwards. This increases the space in your chest cavity into which the lungs expand. The intercostal muscles between the ribs also help in enlarging the chest cavity. Whereas during exhalation the diaphragm relaxes and moves upwards into the chest cavity.