What is the most important muscle for respiration?

What is the most important muscle for respiration?

Diaphragm

Internal and external intercoastal muscles
Radial muscles

Or intersectoral muacles

Inter costal muscle esscial for breathing

Or diaphragm

Phrenic muscles and external and internal inter coastal muscles.

Diaphragm first and external and internal intercontinental muscle second

Dpgm, Ext and Int intercostal mus