On inspiration, the diaphragm becomes flatter and moves down, whilst the external intercostals contract to move the ribcage up and out.

The diaphragm (innervated by the phrenic nerve) is the dominant contributor during quiet breathing.

Question: From what spinal levels does the phrenic nerve originate?

Click here for answer.

On inspiration, the diaphragm becomes flatter and moves down, whilst the external intercostals contract to move the ribcage up and out.

The diaphragm (innervated by the phrenic nerve) is the dominant contributor during quiet breathing.

Question: From what spinal levels does the phrenic nerve originate?

Answer: C3, C4 and C5.