Question

Which nerve is required for GAG reflex

• A. 9th cranial nerve
• B. 10th cranial nerve
• C. 11th cranial nerve
• D. 12th cranial nerve

Answer 1

The Correct Option is A

The gag reflex, also known as the pharyngeal reflex, is an important protective mechanism of the body that prevents the aspiration of foreign bodies and prevents choking. It involves a complex neural mechanism that includes sensory, central, and motor components. Understanding which cranial nerves are involved in this reflex can aid in clinical diagnostics and anatomical studies.

Explanation:

• 9th Cranial Nerve (Glossopharyngeal Nerve): This nerve is primarily responsible for the afferent sensory limb of the gag reflex. It innervates the posterior third of the tongue, tonsils, and the pharyngeal wall, and carries sensory information to the brainstem. When these areas are stimulated, the glossopharyngeal nerve transmits signals to the medulla oblongata.
• 10th Cranial Nerve (Vagus Nerve): This nerve plays an integral role in the efferent motor component of the gag reflex. It innervates muscles of the pharynx and larynx and causes the reflexive contraction necessary to protect the airway.
• 11th Cranial Nerve (Accessory Nerve) and 12th Cranial Nerve (Hypoglossal Nerve): These nerves are not primarily involved in the gag reflex, though the accessory nerve assists in certain pharyngeal activities, and the hypoglossal nerve is responsible for movements of the tongue.

For the initiation of the gag reflex, the stimulus is carried by the glossopharyngeal nerve. Therefore, the correct answer is the 9th cranial nerve.