The 10th cranial nerve that provides parasympathetic control of the heart is the:

The 10th cranial nerve that provides parasympathetic control of the heart is the:

• A. Glossopharyngeal Nerve
• B. Hypoglossal Nerve
• C. Facial Nerve
• D. Vagus Nerve

Answer: (D)

Parasympathetic control of the heart is provided by the tenth cranial nerve. It carries preganglionic parasympathetic fibers that reach the heart and terminate in intrinsic cardiac ganglia near the SA and AV nodes. The neurotransmitter acetylcholine acts on muscarinic receptors (mainly M2) to slow the heart rate and reduce conduction through the AV node. This parasympathetic input helps keep heart rate at rest. The other nerves listed do not regulate heart parasympathetically: one supplies parasympathetic fibers to salivary glands, another to glands of the face, and another is a motor nerve to the tongue. Hence, the nerve responsible for parasympathetic control of the heart is the vagus nerve.

Parasympathetic control of the heart is provided by the tenth cranial nerve. It carries preganglionic parasympathetic fibers that reach the heart and terminate in intrinsic cardiac ganglia near the SA and AV nodes. The neurotransmitter acetylcholine acts on muscarinic receptors (mainly M2) to slow the heart rate and reduce conduction through the AV node. This parasympathetic input helps keep heart rate at rest.

The other nerves listed do not regulate heart parasympathetically: one supplies parasympathetic fibers to salivary glands, another to glands of the face, and another is a motor nerve to the tongue. Hence, the nerve responsible for parasympathetic control of the heart is the vagus nerve.