Cardiac Vagal Ganglia

The vertebrate nervous system is divided into two major components: the central nervous system and the peripheral nervous system, which can be in turn subdivided into somatic and autonomic components. The autonomic component of the peripheral system regulates the functionalism of the internal organs including the heart. Sensory afferent pathways with sympathetic and parasympathetic components relay information from the heart to the brain. Sympathetic afferent nerves travel through the stellate ganglia of the sympathetic chain, and connect with motor neurons in the spinal cord. Parasympathetic postganglionic efferent nerves may arise mainly from the brain stem and also from the spinal cord and synapse with postganglionic neurons located in the heart. In the latter scenario, acetylcholine is the main neurotransmitter, which contributes to decrease heart rate and contractility. The human heart has five major atrial ganglionated plexuses (superior right and left atrial, posterior right atrial, posteromedial left atrial and posterolateral left atrial) as well as five major ventricular ganglionated plexus (aortic root, anterior and posterior descending, right acute marginal and obtuse marginal).