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CNs 5, 7, 9, 10 - Pharnygeal Arch Set - Motor USMLE, Limited Edition > Neuroscience > Neuroscience PHARYNGEAL ARCH SET, CNS 5, 7, 9, 10 • They are derived from the pharyngeal (aka branchial) arches • They have special motor and autonomic motor functions CRANIAL NERVES EXIT FROM THE BRAINSTEM CN 5, the trigeminal nerve exits the mid/lower pons.* CN 7, the facial nerve exits the pontomedullary junction.* CN 9, the glossopharyngeal nerve exits the lateral medulla.* CN 10, the vagus nerve exits the lateral medulla.* CRANIAL NERVE NUCLEI AT BRAINSTEM LEVELS Midbrain • The motor trigeminal nucleus of CN 5. Nerve Path: • The motor division of the trigeminal nerve passes laterally to enter cerebellopontine angle cistern. Pons • The facial nucleus of CN 7. • The superior salivatory nucleus of CN 7. Nerve Path: • CN 7 sweeps over the abducens nucleus as it exits the brainstem laterally in an internal genu, which generates a small bump in the floor of the fourth ventricle: the facial colliculus • Fibers emanate from the superior salivatory nucleus, as well. Medulla • The dorsal motor nucleus of the vagus, CN 10 • The inferior salivatory nucleus, CN 9 1 / 3 • The nucleus ambiguus, CNs 9 and 10. Nerve Paths: • CNs 9 and 10 exit the medulla laterally through the post-olivary sulcus to enter the cerebellomedullary cistern. THE TRIGEMINAL NERVE, CN 5  • The motor division of the trigeminal nerve innervates the muscles of mastication • It passes ventrolaterally through the cerebellopontine angle cistern and exits through foramen ovale as part of the mandibular division (CN 5[3]). Clinical Correlation - Trigeminal Neuropathy THE FACIAL NERVE, CN 7  • The facial nucleus innervates the muscles of facial expression • It spans from the lower pons to the pontomedullary junction. • The superior salivatory nucleus activates select facial glands. • It lies just above the pontomedullary junction. Clinical Correlations - - Facial Palsy - Facial Neuropathy Nerve Path: • CN 7 exits the brainstem at the pontomedullary junction and passes through the internal acoustic meatus. • The sweep over the abducens nucleus is called the internal genu; it generates a small bump in the floor of the fourth ventricle, called the facial colliculus. THE GLOSSOPHARYNGEAL AND VAGUS NERVES, CNS 9 & 10   • The inferior salivatory nucleus of CN 9 is a small nucleus in the upper medulla. • The dorsal motor nucleus of the vagus spans the remainder of the medulla. • Nucleus ambiguus spans the height of the medulla. Nerve Paths: 2 / 3 • CNs 9 & 10 exit the medulla and cross the cerebellomedullary cistern to exit through the jugular foramen. • CN 9 functions in salivation, swallow, and cardio-pulmonary function. • CN 10 functions in gut motility, swallow, and cardio-pulmonary function. - See this video on palatal weakness. Additional: • CNs 9 and 10 exit the medulla laterally through the post-olivary sulcus to enter the cerebellomedullary cistern. • Jugular foramen contents: CNs 9, 10, and 11 and the internal jugular vein. • Carotid space contents: CNs 9, 10, 11, and 12, the internal jugular vein, and the internal carotid artery. • Internal carotid arteriopathy (eg, carotid dissection) with resultant arterial expansion can compress the neighboring cranial nerves (9, 10, 11, and 12) and cause cranial neuropathies. Powered by TCPDF (www.tcpdf.org) 3 / 3.

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