Question

List the events of inspiration beginning with stimulation of the phrenic nerves

Answer 1

The events of inspiration begins with the;
Impulses are conducted on the phrenic nerve to muscle fibers in the diaphragm contracting them.
As the dome shaped diaphragm moves downward the thoracic cavity expands.
At the same time the external intercostal muscles may contract raising the ribs and expanding the thoracic cavity further.
The intra-alveolar pressure decreases 
Atmospheric pressure greater than intra-alveolar pressure forces the air into the respiratory tract through the air passages.
The lungs fill with air.