In nucleus ambiguus, originating fibers of all the following are present except:

Ans. d (Hypoglossal nerve) (Ref. BDC Vol. III 4th/pg. 324, 325)NUCLEUS AMBIGUUSA. Most axons are in CN X# Innervates striated muscles of palate, pharynx, larynx# Efferent limb of 'gag reflex'# Lesion: difficult swallowing (because innervates pharynx)B. 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 Horner's syndrome hiccup - for reasons not known; solitary nucleus may also be destroyed - leading to loss of taste on ipsilateral half of tongue.