cranial nerves

cranial nerves

1. CN I: olfactory

   • (S) function: smell
     • origin: olfactory receptor neurons in olfactory mucosa
       • location: cribriform plate of ethmoid bone

2. CN II: optic

   • (S) function: vision
     • origin: retinal ganglion cells
       • location: optic canal

3. CN III: occulomtor

   • (M) function: most eye movements, pupillary constriction
     • origin: midbrain (anterior aspect)
       • location: superior orbital fissure

4. CN IV: trochlear

   • (M) function: superior oblique (depresseseye and rotates laterally)
     • origin: midbrain (dorsal/ posterior aspect)
       • location: superior orbital fissure

5. CN V- trigeminal

   • (S+M) function: sensation from face, muscles of mastication
     • V1: opthalmic
       • (S) function: sensation from forehead, nose
         • origin: pons
           • location: superior orbital fissure
     • V2: maxillary
       • (S) function: sensation from cheeks, upper lip
         • origin: pons
           • location: foramen rotundum
     • V3: mandibular
       • (S+M) function: sensation from chin, jaw, mouth, muscles of mastication
         • origin: pons
           • location: foramen ovale

6. CN VI: abducens

   • (M) function: lateral rectus (abducts the eye)
     • origin: pons (nuclei underlying floor of 4th ventricle)
       • location: superior orbital fissure

7. CN VIII: vestibulocochlear

   • (S) function: proprieception; acoustic branch: hearing, vestibular branch: equilibrium
     • origin: CB pontine angle, lateral to CN VII
       • location: internal acoustic canal

8. CN IX: glossopharyngeal

   • (S+M) function: taste (posterior 1/3 of tongue), sensation from tonsils, senses carotid BP from carotid arteries and sinus, stylopharyngeus (swallowing, larynx, pharynx), parotid gland secretion (salivary gland back of mouth)
     • origin: medulla
       • location: jugular foramen

9. CN VII: facial

   • (S+M) function: taste (anterior 2/3 of tongue), muscles of facial expression, lacrimal + salivary gland secretion
     • origin: pons (CB pontine angle) above olive, medial to CN VIII
       • location: runs through acoustic canal, then through facial canal, exiting at stylomastoid foramen

10. CN X: vagus

    • (S+M) function: taste (epiglottis), sensation from meninges, pharynx, senses aortic BP at aortic arch, muscles in pharynx and larynx, parasympathetic (ie rest and digest) fibres to heart, lungs, digestive tract
      • origin: medulla (posterolateral sulcus)
        • location: jugular foramen

11. CN XI: (spinal) accessory

    • (M) function: trapezius and sternocleidomastoid (shrug and head movements)
      • origin: cranial and spinal roots
        • location: jugular foramen

12. CN XII: hypoglossal

    • (M) function: tongue muscles (speech articulation and swallowing/bolus formation)
      • origin: medulla
        • location: hypoglossal canal

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