Contraction of the Diaphragm ____

Question

Contraction of the diaphragm ____.  
A) diminishes the volume of the thoracic cavity
B) increases the volume of the thoracic cavity
C) pushes the rib cage downward
D) causes external intercostal muscles to relax
E) decreases lung capacity

Accepted Answer

Contraction of the diaphragm increases the volume of the thoracic cavity, which leads to inhalation. This occurs because the dome-shaped diaphragm moves down, which increases the vertical dimension of the thoracic cavity. This creates a negative pressure within the lungs, allowing air to be drawn in.