Respiration, the exchange of oxygen and carbon dioxide within the body's tissues, is primarily an involuntary process controlled by many mechanisms including nervous control, chemical control, some voluntary control, body temperature, drugs, pain, emotion, sleep, baroreceptors, and proprioceptors.

The medullary rhythmicity area is the respiratory control center of the central nervous system located in the medulla oblongata. The respiratory control center can be divided into the inspiratory center and expiratory center. The inspiratory center spontaneously controls the diaphragm and intercostal muscles responsible for inspiration. These inspiratory muscles are connected to the medulla oblongata via spinal nerves. Contraction of the diaphragm is controlled by two phrenic nerves that emanate from the third, fourth, and fifth cervical spinal nerves. Eleven pairs of intercostal nerves that commence from the first 11 thoracic spinal nerves regulate the intercostal muscles. Under normal, resting conditions, there is no activity within the...