Answer
The diaphragm, the major muscle of breathing, is innervated by the phrenic nerve.
Work Step by Step
The phrenic nerve originates in the neck-- in the region of C3-C5. It descends through the thorax to the diaphragm, and provides its major motor innervation. The phrenic nerve is a paired mixed nerve. Each nerve supplies the ipsilateral side. In addition to motor fibers, it contains sensory fibers from peritoneum, pleura pericardium liver and pancreas; it also has ANS sympathetic fibers. The diaphragm is the major muscle of external respiration, but intercostal muscles assist in this process.
Contractions of the diaphragm also help in the evacuation of pelvic cavity organs during urination, defecation, and childbirth.
