The heart is primarily supplied by autonomic nerves known as cardiac nerves. These nerves are part of the autonomic nervous system, which controls involuntary functions. Specifically, both sympathetic and parasympathetic nerves contribute to the innervation of the heart.
Autonomic Nerves Innervating the Heart
The autonomic innervation of the heart consists of both sympathetic and parasympathetic components, influencing heart rate, contractility, and conduction velocity.
-
Sympathetic Nerves: These nerves originate from the thoracic spinal cord and travel to the heart via the sympathetic chain ganglia. The sympathetic cardiac nerves include:
- Superior cardiac nerve (nervus cardiacus cervicalis superior)
- Middle cardiac nerve (nervus cardiacus cervicalis medius)
- Inferior cardiac nerve (nervus cardiacus cervicalis inferior)
- Direct branches from the upper thoracic ganglia
Sympathetic stimulation generally increases heart rate and force of contraction, preparing the body for "fight or flight."
-
Parasympathetic Nerves: These nerves originate from the vagus nerve (cranial nerve X). Branches from the vagus nerve, specifically the superior and inferior cardiac branches, provide parasympathetic innervation to the heart.
Parasympathetic stimulation generally decreases heart rate and force of contraction, promoting "rest and digest" functions.
Summary
The heart receives its nerve supply from both sympathetic and parasympathetic branches of the autonomic nervous system, allowing for precise regulation of cardiac function. The main nerves involved are the cardiac nerves originating from the cervical and thoracic sympathetic ganglia, and the vagus nerve.
