Innervation of the heart (2024)

Author: Niamh Gorman, MSc•Reviewer: Francesca Salvador, MSc
Last reviewed: October 25, 2022
Reading time: 6 minutes

Recommended video: Innervation of the heart[05:29]

Autonomic innervation of the heart seen from the anterior view of open thorax.

Cardiac plexus

Plexus cardiacus

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Synonyms: none

The innervation of the heart refers to the network of nerves that are responsible for the functioning of the heart. The heart is innervated by sympathetic and parasympathetic fibres from the autonomic branch of the peripheral nervous system.

Key facts about the innervation of the heart
Parasympathetic efferent fibers	Vagus nerve Function:reducing the heart rate, reducing the force of contraction of the heart, vasoconstriction of the coronary arteries
Sympathetic efferent fibers	Cardiac nerves from the lower cervical and upper thoracic ganglia Function:increasing heart rate, increasing the force of contraction of the myocardium
Afferent parasympathetic fibers	Vagal cardiac nerves Function: feedback on blood pressure
Afferent sympathetic fibers	Afferents to upper thoracic and lower cervical ganglia Function: feedback on blood pressure, pain sensation
Clinical relations	Cardiac plexus injury, referred pain

Cardiac plexus

The cardiac plexus is a network of nerves including both the sympathetic and parasympathetic systems. It is split into two parts. The superficial part is located below the arch of the aorta, and between the arch and the pulmonary trunk.

Have you already mastered the basic anatomy of the heart? Test yourself now with our handy diagrams, quizzes and worksheets of the heart.

The deep part lies between the arch of the aorta and the bifurcation of the trachea. Small mixed fibres (containing both sympathetic and parasympathetic fibres) branch off of the cardiac plexus and supply:

the conduction system of the heart
the coronary vasculature
the myocardium (muscle) of the atria and ventricles

Parasympathetic innervation

Vagus nerve

Nervus vagus

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Synonyms: Cranial nerve X, CN X, show more...

Sympathetic innervation

Cervicothoracic ganglion

Ganglion cervicothoracicum

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Synonyms: Stellate ganglion, Ganglion stellatum

The sympathetic part of the cardiac plexus is composed of fibres from the sympathetic trunk, arising from the upper segments of the thoracic spinal cord. Fibres from the sympathetic trunk reach the cardiac plexus via cardiac nerves. The preganglionic fibres branch from the upper thoracic spinal cord and synapse in the lower cervical and upper thoracic ganglia. Postganglionic fibres extend from the ganglia to the cardiac plexus.

Sympathetic nerves are responsible for:

increasing heart rate
increasing the force of contraction of the myocardium
the ‘fight or flight’ response, causing our heart to beat faster.

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Cardiac afferents

Afferent fibres also form part of the cardiac plexus. They return to the central nervous system via both the sympathetic cardiac branches and the cardiac nerves from the right and left vagus nerves.

The afferents passing through the cardiac branches of vagus nervesprovide feedback on blood pressure and blood chemistry.

In the sympathetic branch, the visceral afferents return to the upper thoracic and lower cervical ganglia. The fibres entering the upper cervical region are typically redirected down towards the upper thoracic portions of the sympathetic trunk, where they reenter the upper thoracic regions of the thoracic spinal cord, joining afferents from the thoracic ganglia. Sympathetic afferents relay pain sensation from the heart.

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Innervation of the heart Explore study unit

Clinical notes

Cardiac plexus injury

Injury to the cardiac plexus, or in fact, to any of the contributaries to the cardiac plexus can impair the function of the heart. Damage to the vagus nerves, providing the parasympathetic innervation of the heart, will affect the ability to decrease the heart rate, leading to tachycardia. Similarly, damage to the sympathetic fibres contributing to the cardiac plexus can reduce the ability to increase heart rate, causing bradycardia.

Referred pain

The pain conducting sympathetic afferents transmit pain sensation. This pain sensation can be detected at a cellular level in incidences where tissue damage to the heart occurs. These incidences include cardiac ischemia and myocardial infarction. The pain can often be felt in cutaneous regions. This is because some of the dermatomes responsible for cutaneous innervation are supplied by the same spinal cord levels as the visceral afferents from the heart. This is the mechanism behind pain being felt in the right shoulder region that is a characteristic symptom of a myocardial infarction.

Sources

All content published on Kenhub is reviewed by medical and anatomy experts. The information we provide is grounded on academic literature and peer-reviewed research. Kenhub does not provide medical advice. You can learn more about our content creation and review standards by reading our content quality guidelines.

References:

F. Netter: Atlas of Human Anatomy, 6th Edition, Elsevier Saunders (2014).
R. Drake, A.W. Vogl, A.W.M. Mitchell: Gray’s Anatomy for Students, 3rd Edition, Churchil Livingston Elsevier (2015).
S. Standring: Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 40th Edition, Churcill Livingstone Elsevier (2008).

Illustrators:

Cardiac plexus (ventral view) -Yousun Koh
Vagus nerve (lateral-left view) - Paul Kim
Inferior cardiac nerve (lateral-left view) - Paul Kim
Sympathetic trunk (dorsal view) -Yousun Koh

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