Nerve roots of the phrenic nerve

The video explains the innervation of the diaphragm by the phrenic nerve, which originates from the C3, C4, and C5 spinal nerves. These nerve roots are crucial for the diaphragm's function, enabling breathing by altering intrathoracic pressure. The mnemonic 'C3, C4, C5 keep the diaphragm alive' helps remember this concept.

What happens to intrathoracic pressure when the diaphragm contracts?

Why is it said that C3, C4, and C5 keep the diaphragm alive?