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Multiple Choice
The __________ nerve carries parasympathetic fibers to the sinoatrial (SA) node.
A
facial
B
hypoglossal
C
vagus
D
accessory
Verified step by step guidance
1
Identify the role of the sinoatrial (SA) node in the heart. The SA node is responsible for initiating the electrical impulses that set the pace for the heart rate.
Understand the function of parasympathetic fibers. These fibers are part of the autonomic nervous system and help to decrease heart rate by influencing the SA node.
Recognize the cranial nerves involved in parasympathetic innervation. The vagus nerve (cranial nerve X) is the primary nerve that carries parasympathetic fibers to the heart.
Differentiate between the cranial nerves listed: facial (VII), hypoglossal (XII), and accessory (XI). None of these nerves are responsible for carrying parasympathetic fibers to the heart.
Conclude that the vagus nerve is the correct answer, as it is the nerve that carries parasympathetic fibers to the SA node, influencing heart rate.