NEET PG DENTAL EXAM

Detailed explanation-1: -Contraction of external inter-costal muscles lifts up the ribs and sternum increasing the volume of thoracic chamber leading increase in pulmonary volume and decrease in intra-pulmonary pressure to less than the atmospheric pressure. This forces the air from outside to move into the lungs.

Detailed explanation-2: -Contraction of these muscles raises the rib cage upward and outward, thereby contributing to the expansion of the thoracic cavity and reduction of pressure within the lung, causing air to move from the air into the lungs (see Figure 6.1. 3).

Detailed explanation-3: -When the diaphragm contracts, it moves inferiorly toward the abdominal cavity, creating a larger thoracic cavity and more space for the lungs. Contraction of the external intercostal muscles moves the ribs upward and outward, causing the rib cage to expand, which increases the volume of the thoracic cavity.