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The gag reflex is a reflex contraction of the back of the throat, elicited by touching the posterior pharyngeal wall, tonsillar area, or the base of the tongue. Stimulation results in a visible contraction of the pharyngeal wall. The gag reflex is a protective response that prevents oral contents from entering the throat except as part of normal swallowing and helps prevent choking. The afferent limb of the reflex is supplied by the glossopharyngeal nerve (cranial nerve IX), which inputs to the nucleus solitarius and the spinal trigeminal nucleus. The efferent limb is supplied by the vagus nerve (cranial nerve X) from the nucleus ambiguus. All of these are located in the medulla. The lower cranial nerves are involved in pharyngeal and laryngeal function as well as in movements of the neck and tongue. Damage to them can result in problems with speech and swallowing. These nerves are commonly affected by conditions that damage the medulla or cause...