While there isn't a single "main" nerve of the heart, the heart's function is heavily influenced by a network of autonomic nerves called cardiac nerves. These nerves are part of the autonomic nervous system, which controls involuntary functions.
Here's a breakdown of the key cardiac nerves:
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Sympathetic Cardiac Nerves: These nerves originate from the cervical and upper thoracic ganglia and generally increase heart rate, contractility, and conduction velocity. Examples include:
- Superior cardiac nerve (nervus cardiacus cervicalis superior)
- Middle cardiac nerve (nervus cardiacus cervicalis medius)
- Inferior cardiac nerve (nervus cardiacus cervicalis inferior)
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Parasympathetic Cardiac Nerves (Vagus Nerve): The vagus nerve (cranial nerve X) provides parasympathetic innervation to the heart. It primarily decreases heart rate and contractility. Branches of the vagus nerve travel to the cardiac plexus and influence the sinoatrial (SA) and atrioventricular (AV) nodes.
Therefore, rather than a single "main" nerve, the heart's function depends on a balance between sympathetic and parasympathetic influences, primarily mediated by the cardiac nerves arising from the sympathetic trunk and the vagus nerve. Understanding the interaction of these nerves is crucial in understanding heart function.
