The carotid body, located at the bifurcation of the common carotid artery, contains glomus type I cells that sense arterial hypoxia. The afferent limb of the resulting chemoreceptor reflex travels through which nerve?

• A Glossopharyngeal nerve via the nerve of Hering ✓
• B Vagus nerve
• C Hypoglossal nerve
• D Sympathetic chain fibres from the superior cervical ganglion

Explanation

Chemoreceptor afferents from the carotid body ascend in the sinus nerve (nerve of Hering), a branch of the glossopharyngeal nerve, and reach the petrosal ganglion of IX before entering the medulla. Sympathetic fibres reach the carotid body only as efferent vasomotor supply, so option D cannot carry the afferent limb. The vagus supplies the aortic bodies instead.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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