Cranial Nerves - Iii (Cn Ix, X, Xi & Xii)
CRANIAL NERVES - III (CN IX, X, XI & XII) DR. SANGEETA KOTRANNAVAR ASSISTANT PROFESSOR DEPT. OF ANATOMY USM KLE IMP BELAGAVI OBJECTIVES • Describe the functional component, nuclei of origin, course, distribution and functional significance of cranial nerves IX, X, XI and XII • Describe the applied anatomy of cranial nerves IX, X, XI and XII overview Relationship of the last four cranial nerves at the base of the skull The last four cranial nerves arise from medulla & leave the skull close together, the glossopharyngeal, vagus & accessory through jugular foramen, and the hypoglossal nerve through the hypoglossal canal Functional components OF CN Afferent Efferent General General somatic afferent fibers General somatic efferent fibers Somatic (GSA): transmit exteroceptive & (GSE): innervate skeletal muscles proprioceptive impulses from skin of somatic origin & muscles to somatic sensory nuclei General General visceral afferent General visceral efferent(GVE): transmit visceral fibers (GVA): transmit motor impulses from general visceral interoceptive impulses motor nuclei &relayed in parasympathetic from the viscera to the ganglions. Postganglionic fibers supply visceral sensory nuclei glands, smooth muscles, vessels & viscera Special Special somatic afferent fibers (SSA): ------------ Somatic transmit sensory impulses from special sense organs eye , nose & ear to brain Special Special visceral afferent fibers Special visceral efferent fibers (SVE): visceral (SVA): transmit sensory transmit motor impulses from the impulses from special sense brain to skeletal muscles derived from taste (tounge) to the brain pharyngeal arches : include muscles of mastication, face, pharynx & larynx Cranial Nerve Nuclei in Brainstem: Schematic picture Functional components OF CN GLOSSOPHARYNGEAL NERVE • Glossopharyngeal nerve is the 9th cranial nerve. • It is a mixed nerve, i.e., composed of both the motor and sensory fibres, but predominantly it is sensory.
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