Cranial Nerves

Cranial Nerves

1. Site of exit from skull

   • Cribriform plate (CN I)
   • Optic canal (CN II)
   • Superior orbital fissure (CN III, IV, Ophthalmic branch of CN V, CN VI)
   • Foramen rotundum (Maxillary branch of CN V)
   • Foramen ovale (Mandibular branch of CN V)
   • Internal acoustic meatus (CN VII, VIII)
   • Jugular foramen (CN IX, X, XI)
   • Hypoglossal canal (CN XII)

2. Facial nerve

   • Temporal branch
   • Zygomatic branch
   • Buccal branch
   • Marginal mandibular branch
   • Cervical
   • Parasympathetic to lacrimal, submandibular and sublingual glands
   • Muscles of facial expression, stapedius, stylohyoid, posterior belly of the digastric muscle
   • Taste from anterior 2/3 of the tongue
   • Bell's palsy
   • Runs through parotid gland

3. Glossopharyngeal nerve

   • Parasympathetic to parotid gland, stylopharyngeus
   • Sensory from pharynx, middle ear, auditory tube, carotid body and sinus, external ear, posterior 1/3 of tongue (including taste)
   • Lesions: PICA infarct
   • Test: gag reflex

4. Nuclei

   • Midbrain (CN III, IV)
   • Pons (CN V, VI, VII, VIII)
   • Medulla (CN IX, X, XII)
   • Spinal cord (CN XI)

5. Cavernous sinus

   • CN III, IV, VI)
   • CN V (Ophthalmic, Maxillary)
   • Danger triangle
   • Neighboring structures
     • Optic chiasm
     • Pituitary gland
     • Sphenoidal sinuses
     • Internal carotid artery

6. Reticular activating system

   • Reticular formation
   • Mesencephalic nucleus
   • Thalamic intralaminar nucleus
   • Dorsal hypothalamus
   • Tegmentum

7. Vagal nuclei

   • Nucleus solitarius (sensory)
     • Taste
     • Baroreceptors
     • Gut distension
   • Nucleus ambiguous (motor)
     • Pharynx
     • Larynx
     • Upper esophagus
   • Dorsal motor nucleus (autonomic)
     • Heart
     • Lungs
     • Upper GI

8. Horner syndrome

   • Pancoast tumor
   • Brown-Sequard syndrome
   • Late stage syringomyelia