Solitariospinal tract
The solitariospinal tract is a descending nerve tract that controls breathing by promoting the action of inspiratory muscles. It consists of a small group of axons originating in the solitary nucleus of the medulla oblongata, and projects to the motor neurons of the phrenic nerve and of motor neurons of the thoracic nerves. In the spinal cord, it descends in the anterior funiculus and lateral funiculus. Section of the anterior and lateral funiculi appears to abolish rhythmic breathing.
A similar, complimenting pathway also arises from the nucleus retroambiguus in the ventral respiratory group, but it additionally also projects to and promotes motor neurons of the muscles of expiration.