2/13/2024 0 Comments Gag reflex cranial nerve![]() Multiple small lesions in the cortex and/or brainstem interrupt the corticobulbar supply to the motor nuclei of various cranial nerves. This occurs in a condition known as pseudobulbar palsy. See Section V, the Autonomic Nervous System.īilateral supranuclear denervation leads to dysphagia and dysarthria. The vagus nerve has many ramifications of clinical significance, as befits such a complex nerve. It consists of a stabbing, lancinating pain at the base of the tongue or around the palate. Glossopharyngeal neuralgia, similar to trigeminal neuralgia, does occur rarely. Diphtheria can cause ninth nerve paralysis. At the jugular foramen the ninth, tenth, and eleventh nerves can all be involved (e.g., by a glomus tumor or other masses). In the cerebellopontine angle, the eighth and ninth nerves can be involved by tumors. Its ganglia are the nodose and jugular.įor all practical purposes, the ninth nerve cannot be tested separately, and isolated lesions are almost unknown. With a few exceptions, it supplies all the muscles of the soft palate, pharynx, and larynx, in addition to the structures in the pulmonary, gastrointestinal, and cardiovascular systems previously mentioned. Areas supplied include the posterior third of the tongue and posterior pharynx, soft palate, the stylopharyngeus muscle, the pharyngeal plexus, secretory glandular fibers, and other areas.Īfter leaving the jugular foramen, the vagus nerve courses in the internal carotid sheath and is widely distributed to the upper gastrointestinal system. The nerve descends on the side of the pharynx and then enters the pharynx. The superior and petrosal ganglia of the glossopharyngeal nerve are in the jugular foramen. The roots of the ninth and tenth nerves exit together from the medulla and leave the skull through the jugular foramen in the company of the eleventh nerve. Pain sensation from the dura of the posterior fossa also travels here via the jugular ganglion. Pain and temperature impulses from certain parts of the ear reach this nucleus via the petrosal ganglion of the ninth and the jugular ganglion of the tenth nerve. The second sensory group comprises the nucleus of the spinal tract of the trigeminal nerve (see Chapter 61, The Trigeminal Nerve, for a description of this nucleus). They include the following:Ĭhemoreceptor and baroreceptor impulses from the aorta and carotid arteries. 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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