![]() The sensory fibers carried in the ninth nerve have their cell station in the superior or petrosal ganglion. It is a long nuclear column extending the length of the medulla, located lateral to the dorsal motor nucleus of the vagus, that receives sensory fibers from the ninth, tenth, and seventh (via the nervus intermedius) nerves. Sensory nuclei include the solitary tract and nucleus, also known as the gustatory nucleus. The principal supranuclear control is from the hypothalamus there may be cortical innervation. They cause secretion of various glands of the gastrointestinal system. Parasympathetic fibers originating in these nuclei supply smooth muscles in the pulmonary, gastrointestinal, and cardiovascular systems. The other motor nuclei are the dorsal motor nucleus (X) and the inferior salivary nucleus (IX), located in the medulla dorsal and lateral to the twelfth nucleus. There are multiple connections with nuclei of neighboring brainstem nuclei for coordination of swallowing, gagging, and coughing. Supranuclear innervations from the lower part of the precentral gyrus are partly crossed and partly uncrossed. It supplies the striated ("branchial") muscles of the pharynx, larynx, and upper esophagus via the ninth, tenth, and eleventh nerves. ![]() The nucleus ambiguus is a motor nucleus located in the mid to upper medulla. Two groups of motor and sensory nuclei serve these nerves. ![]() See Chapter 62 on the facial nerve and taste for the testing of taste. Laryngoscopy is necessary to evaluate the vocal cord. Gently touch first one and then the other palatal arch with a tongue blade, waiting each time for gagging. Now warn the patient that you are going to test the gag reflex. With paralysis there is no elevation or constriction of the affected side. Normal palatal arches will constrict and elevate, and the uvula will remain in the midline as it is elevated. Observe the palatal arches as they contract and the soft palate as it swings up and back in order to close off the nasopharynx from the oropharynx. Ask the patient to say "ahhh" as long as possible. Use a tongue blade to depress the base of the tongue gently if necessary. Have the patient open the mouth and inspect the palatal arch on each side for asymmetry. Give the patient a glass of water to see if there is choking or any complaints as it is swallowed. Hoarseness, whispering, nasal speech, or the complaint of aspiration or regurgitation of liquids through the nose should make you especially mindful of abnormality. Listen to the patient talk as you are taking the history.
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