![]() It provides many fibre types, which are shown in the table below. ![]() It draws more fibres from the inferior salivatory nucleus (parotid gland) and dorsal motor nucleus (DMX pharyngeal sensation).It draws fibres from the solitary nucleus (taste) and nucleus ambiguus (motor).Reflex arcs are much the same – a stimulus on the oropharyngeal mucosa that is large enough or present for long enough will begin to elicit a gag reflex, even in those who say they don’t have a gag reflex! We know that action potentials require either spatial summation (lots of stimuli at once) or temporal summation (rapid and repetitive stimuli) to elicit a signal. A reflex arc, much like an action potential, needs adequate stimulation to begin. Up to 20% of patients suggest they have no gag reflex. Interestingly, an absent gag reflex may not be pathological. 2Ĭlinical relevance: the interface of neurophysiology and medicine The lesser petrosal nerve synapses at the otic ganglion, where the parasympathetic fibres then travel with the auriculotemporal nerve to the parotid gland.įigure 2. * The tympanic nerve takes fibres from the inferior salivatory nucleus and communicates these fibres from the middle ear as the lesser petrosal nerve. There are several mnemonics for this, one such is, “Tom Says To Never Never Leave Vegas.” This also happens to be the rough order of the branches as they leave the glossopharyngeal nerve. Vagal communicating branch: parasympathetic communicating branches with the vagus nerve.Lingual branch: sensory information from the dorsal posterior 1/3 of the tongue.Nerve to dorsal posterior 1/3 of the tongue: special sense of taste from the dorsal posterior 1/3 of the tongue.Nerve to carotid sinus: sensory innervation to the carotid sinus.Tonsillar: sensory and parasympathetic innervation to the tonsils and oropharynx.Stylopharyngeus: motor innervation to the stylopharyngeus.Tympanic: sensory innervation to the mucosa of the middle ear, turning into the lesser petrosal nerve to supply parasympathetic fibres to the parotid gland*.Here is a short summary of the branches of the glossopharyngeal nerve and their functions: It then branches into several small branches that supply the tongue ( lingual branch), tonsils ( tonsillar branch) and pharynx. ![]() At this point, the glossopharyngeal nerve sends sensory fibres to the carotid sinus via the nerve to the carotid sinus.Ĭontinuing down the neck, the glossopharyngeal nerve then enters the pharynx as it passes through the superior and middle pharyngeal constrictor muscles. As the nerve passes the inferior border of the stylopharyngeus muscle, it supplies it with motor fibres. The glossopharyngeal nerve accompanies the internal carotid artery, which lies posteromedial to the nerve. These ganglia appear to be small bulges in the glossopharyngeal nerve next to the jugular foramen. Immediately before entering the jugular foramen, the tympanic nerve branches from CN IX, providing sensory fibres to the middle ear and parasympathetic fibres to the parotid gland.Īs CN IX leaves the jugular foramen, it meets the superior and inferior ganglia (no other special name!), which contain the neuronal cell bodies of the sensory components of CN IX. It travels with CNs X and XI inferolaterally in the posterior cranial fossa to reach the internal os of the jugular foramen. It lies immediately superior to cranial nerves X ( vagus) and XI ( spinal accessory). The fibres from these nuclei all converge to form the glossopharyngeal nerve, which exits the medulla oblongata at the post-olivary sulcus (behind the inferior olives). The glossopharyngeal nerve is formed by each of these separate regions of the brainstem in order to provide sensory, motor and parasympathetic innervation to structures in and around the mouth. The course of some of these nuclei is shown in Figure 2. Spinal trigeminal nucleus: pain and temperature from the tongue.Nucleus ambiguus: motor innervation to stylopharyngeus.Inferior salivatory nucleus: parasympathetic parotid gland.Dorsal motor nucleus: secretomotor to the oropharynx.(Rostral) Solitary nucleus: special sense of taste.The nuclei that contribute to it include: The nuclei for the glossopharyngeal nerve all lie in the inferior pontine and medullary regions of the brainstem. CN IX supplies sensory and parasympathetic innervation to the structures lying around the hyoid cartilage, as we will see later on. The stylopharyngeus muscle attaches to this structure once ossified. The only muscular structure associated with the third pharyngeal arch is the greater horns of the hyoid. ![]() The glossopharyngeal nerve is the nerve associated with the third pharyngeal arch. Cranial nerves and cranial foramina diagram. You might also be interested in our Anatomy Flashcard Collection which contains over 2000 anatomy flashcards in addition to advanced features such as spaced repetition.
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