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Overview

Cranial nerves illustration

Illustration by Ava Yap

 
Snapshot
  • A 35-year-old woman presents to the emergency department with left eye vision loss and headache. She was in her usual state of health until 3 hours prior to presentation, when she developed vision loss and eye pain that worsened with eye movement. She reports that approximately 8 months ago she had left arm numbness that self resolved. On physical exam, her visual acuity is 20/185, and a sluggish response to light on the left eye with the swinging flash-light test is noted. (Optic neuritis likely secondary to multiple sclerosis.)
Introduction
 
Cranial Nerves
Cranial Nerve Type Function Cranial Exit
Notes
  • Olfactory nerve (I)
  • Sensory
  • Olfaction
  • Cribiform plate
  • Only CN without thalamic relay to the cortex                        
  • Optic nerve (II)
  • Sensory
  • Vision
  • Optic canal
-
  • Oculomotor nerve (III)
  • Motor
  • Eye movement via the
    • superior, inferior, and medial rectus
    • inferior oblique muscle
  • Pupillary constriction
  • Accomodation
  • Eyelid opening via innervation of the
    • levator palpebrae muscle
  • Superior orbital fissue
  • Center contains output to ocular muscles which is affected primarily 1st by vascular disease
  • Periphery contains parasympathetic output which is affected 1st by compression
  • Trochlear nerve (IV)
  • Motor
  • Eye movement via innervation of the
    • superior oblique muscle
  • Superior orbital fissue
-
  • Trigeminal nerve (V)
  • Motor and sensory
  • Mastication via the mandibular nerve (V3)
  • Facial sensation via the
    • ophthalmic nerve (V1)
    • maxillary nerve (V2)
    • mandibular (V3)
  • Ophthalmic nerve (V1)
    • superior orbital fissure
  • Maxillary nerve (V2)
    • foramen rotundum 
  • Mandibular nerve (V3)
    • foramen ovale
-
  • Abducens nerve (VI)
  • Motor
  • Eye movement via innervation of the
    • lateral rectus
  • Superior orbital fissure
-
  • Facial nerve (VII)
  • Motor and sensory
  • Facial movement
  • Taste from the anterior 2/3 of tongue
  • Lacrimation
  • Salivation via innervation of the
    • submandibular gland
    • sublingual gland
  • Eyelid closing via innervation of the 
    • orbicularis oculi muscle
  • Stapedius 
    • dampens excessive sound
  • Internal auditory meatus
  • Visceral sensation recieved by nucleus solitarius
  • Vestibulocochlear nerve (VIII)
  • Sensory
  • Hearing
  • Balance
  • Internal auditory meatus
-
  • Glossopharyngeal nerve (IX)
  • Motor and sensory
  • Taste from posterior 1/3 of tongue
  • Swallowing
  • Salivation 
    • parotid gland
  • Monitoring carotid body and sinus chemo- and baroreceptors
  • Stylopharngeus
    • elevates pharynx and larynx
  • Jugular foramen
  • Motor output orginates in nucleus ambiguus
  • Visceral sensation recieved by nucleus solitarius
  • Vagus nerve (X)
  • Motor and sensory
  • Taste from epiglottic region
  • Swallowing
  • Palate elevation
  • Midline uvula
  • Talking
  • Coughing
  • Thoracoabdominal viscera
  • Monitoring aortic arch chemo- and baroreceptors
  • Stimulation of auricular branch can cause vasovagal syncope
  • Jugular foramen
  • Motor output orginates in nucleus ambiguus
  • Visceral sensation recieved by nucleus solitarius
  • Parasympathetic fibers to heart, lungs, and upper GI orginates from dorsal motor nucleus
  • Gives recurrent laryngeal nerve which innervates all laryngeal muscles except cricothyroid
  • Accessory nerve (XI)
  • Motor
  • Head turning and shoulder shrugging
    • sternocleidomastoid muscle
    • trapezius
  • Jugular foramen
  • Motor output orginates in nucleus ambiguus
  • Hypoglossal nerve (XII)
  • Motor
  • Tongue movement
  • Hypoglossal canal
-
 
 

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