Question

the pressure due to atmosphere is very large why are we not crushed under it

Answer 1

The atmospheric pressure is very high(not large) but we are not crushed under it as our body is applying an equal amount of pressure from within the body. 
Hope it helps!

Answer 2

Th pressure due to atmosphere is very large but even then we are not crushed because the blood pressure of our body balances the outer atmospheric pressure.

Hope it helps!