FIG. 1.

Autonomic control of cardiovascular systems. Various nuclei within the medulla oblongata coordinate cardiovascular control and are under control of the cerebral cortex and the hypothalamus. Descending sympathetic projections provide tonic control to spinal sympathetic pre-ganglionic neurons (SPNs) located within the lateral horn of spinal segments T1–L2. Axons of SPNs exit the spinal cord via the ventral root and synapse with post-ganglionic neurons located in the paravertebral ganglia. The post-ganglionic fibers then synapse directly with smooth muscle in the heart and blood vessels. Parasympathetic pre-ganglionic fibers exit the brainstem via the vagus nerve and synapse with post-ganglionic parasympathetic neurons in the cardiac ganglia. Figure adapted with permission from Krassioukov.³⁹