Final answer:
The phrenic nerve is connected to the diaphragm and is innervated by the cervical plexus. It carries motor fibers responsible for muscle contractions for ventilation.
Step-by-step explanation:
The phrenic nerve is connected to the diaphragm at the base of the thoracic cavity. It is innervated by the cervical plexus and connected to the spinal cord at cervical levels 3 to 5. The phrenic nerve carries motor fibers responsible for the muscle contractions that drive ventilation.