Fig 1. Central model of cardiac control.

The classical view of the neuronal populations making up the cardiac neuronal hierarchy. In this view the cardiac neuroaxis is made up of two main neuronal groupings based on their anatomic locations: i) higher center neurons, including those in the medulla and spinal cord (C1-T4 primarily) up to the level of the insular cortex. ii) peripheral ganglia—a) neural somata in intrathoracic extracardiac ganglia (adrenergic postganglionic motor neurons) and b) those on the heart (cholinergic postganglionic motor neurons). In this model, these peripheral neuronal populations are under the control of central neuronal command.