The phrenic nerve serves its function within the respiratory system. The phrenic nerve is a nerve that is located in the neck region, specifically at C3-C5. There is left and a right phrenic nerve that travel on either side of the trachea. It travels down the lung and heart until it reaches the diaphragm (the muscle that is responsible for pushing air out of the lungs when it contracts and allowing air to move inward when it relaxes). The phrenic nerve helps with the respiratory process by relaying motor information to the diaphragm. It also picks up sensory information from the diaphragm.
The phrenic nerve contains motor (for voluntary movement), sensory (to pick up signals), and sympathetic (for involuntary) nerve fibers. It serves as the only motor supply to the diaphragm.