Cranial Nerves

• Cranial Nerve 1 “OLFACTORY”


  For sensory, Smell, Lesion: Anosmia, Most common Contused because of the location, CSF RHINORRHEA (nose) secondary to BASILAR skull fracture, CSF SIALORRHEA (mouth) - drooling, CSF OTORRHEA (ear)
• Cranial Nerve 2 “OPTIC”

  For sensory, Vision, Lesion: Anopsia, Other conditions: Myopia – near sightedness (impaired far vision), Hyperopia – far sightedness (impaired near vision), Presbyopia – old sightedness (blurred vision), Nyctalopia – night blindedness (deficient of vit A) “retinol”, Amaurosis Fugax – Monocular blindness (one eye is blind), Tested by Snellen's chart (central visual acuity) and Confrontation test (peripheral visual acuity), Other tests: ISHIHARA - color vision testing, Tonometry intralocular pressure, Retinoscopy - to measure refraction errors
• Cranial Nerve 3 “OCULOMOTOR”

  For motor, Edinger Westphal Nerve, PERRLA – Pupil Equally Round Reactive to Light Accommodation, Ptosis – drooping of the eyelid (Levator palpebrae superioris muscle), Damage causes Mydriasis (dilated pupil), Anisocoria – unequal size of the pupil, Pupillary Light Reflex, Direct Light reflex (one is constricted) and Consensual effect (both constricted), Formula: EOM3, LR6, SO4, SUPERIOR RECTUS - 3, LATERAL RECTUS - 6, INFERIOR RECTUS - 3, MEDIAL RECTUS - 3, INFERIOR OBLIQUE – 3, SUPERIOR OBLIQUE - 4, Diplopia – double vision (eye patch) - vertical – CN4, - horizontal – CN6, Nystagmus
• Cranial Nerve 4 “trochlear”


  For motor, Superior Oblique
• Cranial Nerve 5 “Trigeminal”

  For sensory and motor, Largest cranial nerve, “Gasserian ganglion”, “Semilunar ganglion”, “MOTOR” - Muscles of Mastication (TIME), Temporalis muscle, Internal (MEDIAL) pterygoid muscle closes the mouth, Masseter muscle, External (LATERAL) pterygoid muscle – opens the mouth, “SENSORY” Facial sensation, CN5 v1 – Ophthalmic (corneal reflex –blink) (Sneeze reflex – 5 v1 is afferent, 9 and 10 is efferent), CN5 v2 – Maxilla, CN5 v3 – Mandible (also motor), Eye Opening – CN3, Eye Closing – CN7
• Cranial Nerve 6 “Abducens”


  For motor, Lateral Rectus
• Cranial Nerve 7 “Facial”


  For sensory and motor, Muscle of Expression, Frowning – Corrugator Supercilii, Surprise – Occipitofrontalis, Smile – Major Zygomaticus, Kissing – Orbicularis Orris, Sucking – Buccinator, Sneezing – Levator Anguli Oris, Blinking/winking – Orbicularis oculi, Egad – platysma
• Muscle movements controlled by Cranial Nerve 7 "Facial"

  1. Frowning – Corrugator Supercilii

  2. Surprise – Occipitofrontalis

  3. Smile – Major Zygomaticus

  4. Kissing – Orbicularis Orris

  5. Sucking – Buccinator

  6. Sneezing – Levator Anguli Oris

  7. Blinking/winking – Orbicularis oculi

  8. Egad – platysma
• Cranial Nerve 7 "Facial"


  • For sensory and motor
• Cranial Nerve 7 "Facial"


  • Sensory – Taste in Anterior 2/3 of the tongue (chorda tympani)
• Cranial Nerve 7 "Facial"

  • Taste – 7/9 (Ageusia)
• Cranial Nerve 7 "Facial"


  • General Sensation Anterior 2/3 – CN5
• Cranial Nerve 7 "Facial"


  • General Sensation Posterior 1/3 – CN9
• Functions of Cranial Nerve 8 "Vestibulocochlear"

  1. Vestibular – Balance, best organ –(Vestibular Apparatus)

  2. Cochlear – Hearing, true organ of hearing – (organ of Corti)
• Cranial Nerve 8 "Vestibulocochlear"


  • For sensory
• Cranial Nerve 8 "Vestibulocochlear"


  • Cortical deafness – area 41 primary hearing
• Cranial Nerve 8 "Vestibulocochlear"


  • Heschl’s Gyrus – pure words deafness
• Special tests related to Cranial Nerve 8 "Vestibulocochlear"


  1. Weber test – lateralization of your hearing loss (middle of your head)

  2. Rinne test – this test compares air conduction with bone conduction (in your mastoid or upper ear)
• Cranial Nerve 9 "Glossopharyngeal Nerve"


  • For sensory and motor
• Cranial Nerve 9 "Glossopharyngeal Nerve"


  • Motor – Stylopharyngeus Muscle
• Cranial Nerve 9 "Glossopharyngeal Nerve"


  • Sensory – Taste and General sensation in posterior 1/3 of tongue
• Cranial Nerve 9 "Glossopharyngeal Nerve"


  • Autonomic function – Parotid Gland
• Cranial Nerve 10 "Vagus"


  • For sensory and motor
• Cranial Nerve 10 "Vagus"


  • Motor – innervates the muscle of the pharynx and muscle of the Larynx
• Cranial Nerve 10 "Vagus"

  • Gag Reflex – Afferent CN9, Efferent CN10
• Cranial Nerve 10 "Vagus"


  • Sensory – skin of pinna of external ear, sensation to the pharynx and to the Larynx and Epiglottis
• Cranial Nerve 10 "Vagus"

  • Autonomic function – 75% of Parasympathetic, it innervates the thorax (heart and lungs), and abdominal (stomach, liver, pancreas, small and large intestine)
• Cranial Nerve 11 "Spinal Accessory"


  • For motor
• Cranial Nerve 11 "Spinal Accessory"


  • Cranial part – Vagal system (10,9,7.1), Spinal part – sternocleidomastoid and trapezius (shoulder Shrug)
• Cranial Nerve 11 "Spinal Accessory"


  • Only CN passing through foramen Magnum
• Cranial Nerve 11 "Spinal Accessory"


  • Lateral winging of the Scapula (sliding door), Radical neck dissection
• Cranial Nerve 12 "Hypoglossal Nerve"


  • For motor
• Cranial Nerve 12 "Hypoglossal Nerve"


  • For the tongue movement
• Dysarthria – hard to speak (also affects CN10, CN7, CN5)
• Location of Brain stem

  • Cn1 – Telencephalon (not in Brainstem)
  • Cn2 - Diencephalon
  • 3 types of Brainstem - Cn3,4
  • Cn5,6,7,8
  • Cn7,8,9,10,11,12
• Brain stem stroke - Weber


  Medial basal midbrain (Cn3)
• Brain stem stroke - Benedikt


  Tegmentum of the midbrain (Cn3)
• Brain stem stroke - Locked-in


  Bilateral basal pons (all in the pons)
• Brain stem stroke - Millard Gabler


  Lateral pons (Cn6,7)
• Brain stem stroke - Wallenburg

  Lateral Medalla (Cn5) (because of Pain and temperature of facial sensation)