The carotid sinus baroreceptors transmit afferent signals primarily through which cranial nerve?

• A. Glossopharyngeal nerve (CN IX)
• B. Vagus nerve (CN X)
• C. Trigeminal nerve (CN V)
• D. Facial nerve (CN VII)

Answer: (A)

Carotid sinus baroreceptors send their afferent signals mainly through the glossopharyngeal nerve. The carotid sinus nerve, also called Hering’s nerve, is a branch of CN IX that conveys the stretch information from the carotid sinus to the nucleus tractus solitarius in the medulla. From there, the reflex adjusts heart rate and vascular tone by increasing parasympathetic output and reducing sympathetic activity when blood pressure rises. The aortic arch baroreceptors, by contrast, transmit primarily via the vagus nerve (CN X). The other nerves listed do not carry these visceral baroreceptor signals.