Quick Facts
Sympathetic Contribution: superior cervical, middle cervical, inferior cervical, and thoracic cardiac nerves.
Parasympathetic Contribution: superior and inferior cervical and thoracic cardiac branches of vagus nerve.
Course: Surrounds the base of heart, aortic arch, pulmonary trunk, and tracheal bifurcation. Divided into the superficial and deep components.
Sympathetic Supply: Increases heart rate, cardiac impulse conduction, force of myocardial contraction, dilates coronary arteries.
Parasympathetic Supply: Decreases heart rate, force of myocardial contraction.
Contributing Nerves
The cardiac plexus is formed by cardiac branches that extend from the right and left vagus nerves and the sympathetic trunk.
The sympathetic component of the cardiac plexus comes from the cardiac branches of the sympathetic trunk; these include superior cervical, middle cervical, inferior cervical, and thoracic cardiac nerves. The cell bodies of their preganglionic sympathetic fibers are found in the intermediolateral cell columns of the superior five or six thoracic segments of the spinal cord. The cell bodies of their postganglionic sympathetic fibers are found in the cervical and superior thoracic paravertebral ganglia of the sympathetic trunks.
The parasympathetic component of the cardiac plexus comes from cardiac branches of the right and left vagus nerves; these include its superior cervical, inferior cervical, and thoracic cardiac branches. The cell bodies of these preganglionic parasympathetic fibers are found in the dorsal nucleus of vagus nerve, found in the brainstem. The cell bodies of their postganglionic parasympathetic fibers are found in the ganglia located either within the cardiac plexus or in the walls of the atria.
Course
The cardiac plexus is the nerve plexus that surrounds the base of the heart, aortic arch, pulmonary trunk, and the tracheal bifurcation. It is arbitrarily divided into the superficial and deep components:
—the superficial component lies anterior and inferior to the aortic arch, and adjacent regions of the heart and pulmonary trunk;
—the deep component lies posterior to the aortic arch and surrounds the distal trachea and tracheal bifurcation.
Branches
Along its course, the cardiac plexus gives off multiple branches; these include the:
—right and left coronary plexuses;
—atrial plexuses;
—right and left pulmonary plexuses.
Supplied Structures
The cardiac plexus provides both sympathetic and parasympathetic innervation to the heart. Both types of nerve fibers wind along the cardiac tissue and arteries, passing primarily to atrial regions, specifically around the sinuatrial node.
The sympathetic fibers lead to dilation of coronary arteries and increased rate and force of cardiac myofiber contraction. Parasympathetic fibers do the opposite, constricting coronary arteries and reducing heart rate.
Visceral sensory fibers traveling through the cardiac plexus convey information relating to pain, blood pressure, and blood chemistry back to the central nervous system via the cardiac splanchnic nerves or the vagus nerve.
