ABSTRACT
The participation of the dorsal medulla oblongata in the regulation of autonomic function has been acknowledged for more than a century, but the pervasive influence of brainstem mechanisms in cardiovascular, respiratory, and gastric control has only been recognized. Information about the involvement of classical neurotransmitters in autonomic regulation is still incomplete, and the significance of neuropeptides in these mechanisms is just being uncovered. Neuronal pathways in the medulla oblongata play two major roles in the reflex control of cardiovascular function. The dorsal medulla is primarily involved in processing cardiovascular afferent information. The nucleus tractus solitarii (NTS) receives afferent information from the cardiopulmonary baroreceptors and chemoreceptors in the IX and X cranial nerves. The ventral medulla contains the “vasomotor centers”, two groups of neurons which receive input from both hypothalamic cardiovascular centers and the NTS in the dorsal medulla, and in turn project to the preganglionic sympathetic neurons in the thoracic spinal cord that innervate circulatory structures.
