<prompt> In nucleus ambiguus, originating fibers of all the following are present except:Glossopharyngeal nerveVagus nerveAccessory nerveHypoglossal nerve  <response>: Ans. d Hypoglossal nerve Ref. BDC Vol. III 4thpg. 324, 325NUCLEUS AMBIGUUSA. Most axons are in CN X Innervates striated muscles of palate, pharynx, larynx Efferent limb of gag reflex Lesion: difficult swallowing because innervates pharynxB. Some axons are in CN IX from rostral portion of nucleus ambiguus Innervates stylopharyngeus Some axons are in CN XI spinal accessory from caudal portion of nucleus ambiguusC. Joins CN 10 and innervates same structuresWallenberg syndrome is infarction in posterior inferior cerebellar artery PICA - lateral medulla 1. lesion in nucleus ambiguus - difficulty in swallowing and hoarseness - loss of gag reflex 2. vestibular nucleus - dizziness and nystagmus 3. trigeminal - loss of pain and temperature on ipsilateral 4. inferior cerebellar peduncle - ipsilateral limb ataxia 5. anterolateral system - reduced pain and temperature on contralateral limb 6. ipsilateral Horners syndrome hiccup - for reasons not known; solitary nucleus may also be destroyed - leading to loss of taste on ipsilateral half of tongue. 