Lab Activity 19 & 20Cranial NervesCN I: Olfactory NerveCN II: Optic NerveCN II: Optic NerveCN II: Optic Nerve PathologyCranial Nerves III, IV & VI (Control Eye Movements)CN III: Oculomotor nerveCN III: Oculomotor Nerve InjuryOculomotor Nerve Injury Right Eye Pupillary ReflexCN IV: Trochlear NerveCN VI: Abducens NerveCN V: Trigeminal NerveCN V: Trigeminal NerveCN V: Trigeminal NerveCN V: Trigeminal NerveCN VII: Facial Nerve CN VII: Facial Nerve CN VII: Facial Nerve TestingCN VII: Facial NerveCN VII: Facial Nerve Injury (Bell’s Palsy)CN VIII: VestibulocochlearCN VIII: Vestibulocochlear TestsCN VIII: Vestibulocochlear Tests Romberg TestCN IX: GlossopharyngealCN IX: GlossopharyngealCN X: Vagus NerveCN X: Vagus NerveCN XI: Accessory NerveCN XI: Accessory NerveCN XI: Accessory NerveCN XII: Hypoglossal NerveHypoglossal Nerve InjuryLab Activity 20General Senses: ReceptorsClasses of MechanoreceptorsPancinian Corpuscle (aka: Lamellated Corpuscle)Meissner’s Corpuscle (aka: Tactile Corpuscle)The EndLab Activity 19 & 20Cranial NervesGeneral SensesPortland Community CollegeBI 2322Cranial Nerves• Nerves that originate from the brain rather than the spinal cord• Part of the peripheral nervous system (not the central nervous system)• May contain one or more of the following:• Sensory• Somatic Motor (voluntary movement)• Parasympathetic Motor (involuntary “rest and digest” part of the autonomic nervous system)3CN I: Olfactory Nerve• Function:• Sensory for smell• Test: Have patient identify aromatic substances like vanilla or coffee (avoid irritating substances like smelling-salts, cloves, mint)• Symptoms of nerve damage: Anosmia: diminished or absent sense of smell4CN II: Optic Nerve• Function:• Sensory for vision• Tests:1. Eye chart2. Check peripheral vision 3. Funduscopic exam5CN II: Optic Nerve• Optic chiasm: Fibers from the nasal halfof each retina cross over to the opposite side of the brain.• Symptoms of nerve damage:• Loss of vision (peripheral or central)• Abnormal funduscopic appearance6CN II: Optic Nerve PathologyPapilledema. Note swelling of the disc, hemorrhages, and exudates, with preservation of the physiologic cup.Proliferative Diabetic Retinopathy. Note the multiple hemorrhages throughout the retina.7Cranial Nerves III, IV & VI(Control Eye Movements)8CN III: Oculomotor nerve• Function:• Somatic Motor to extraocular muscles (voluntarily move the eye)•Parasympathetic (motor) to iris and lens (pupillary constriction)• Tests:1. Check pupils for size, shape and equality2. Shine light in each eye and check for pupil constriction 3. Have patient follow an object in all directions to check for symmetric eye movementsOriginates in the midbrain9CN III: Oculomotor Nerve Injury• Symptoms of nerve damage:• Double vision (diplopia): The affected eye turns outward when the unaffected eye looks straight ahead• The affected eye can move only to the middle when looking inward and cannot look upward and downward. • Ptosis: eyelid droop• Pupil may be dilated and sometimes fixed10Oculomotor Nerve Injury Right Eye Normal sideInjured side11Pupillary ReflexEfferent AfferentConsensual reflex: Both pupils should constrict at the same time12CN IV: Trochlear Nerve• Function:• Somatic motor to superior oblique muscle of the eye.•Test: Check eye movements• Symptoms of nerve damage:• Outward rotation of the affected eye • Vertical diplopiaInjured sideNormal sideOriginates in the midbrain13CN VI: Abducens Nerve• Function:• Somatic Motor to lateral rectus muscle of the eye.•Test: Check eye movements• Symptoms of nerve damage:• The affected eye will tend to be deviated inward because of the unopposed action of the medial rectus muscle. • Cannot move eyeball laterally beyond the midpointInjured sideNormal sideOriginates in the pons14CN V: Trigeminal Nerve3 Branches1. Ophthalmic2. Maxillary3. Mandibular15CN V: Trigeminal Nerve• Function:• Somatic Motor (mandibular branch) to muscles of mastication (chewing)•Sensory (all branches)to face and cornea.Originates in the pons16CN V: Trigeminal NerveTest: Have patient bite down while you palpate the masseter muscleTest: Touch patient with an open paperclip and ask “sharp or dull”Test: Touch cornea with a wisp of cotton. Patient should blink17CN V: Trigeminal Nerve• Symptoms of nerve damage:• Inability to firmly bite down (mandibular branch only)• Loss of sensation (each branch can be affected independently)• Loss of corneal reflex (may indicate brain stem injury)• Trigeminal Neuralgia (Tic Douloureux): debilitating intermittent pain on one side of the face18CN VII: Facial Nerve5 Branches1. Temporal2. Zygomatic3. Buccal4. Mandibular5. Cervical•Function:• Somatic Motor to muscles of facial expression• Parasympathetic (motor) to lacrimal and salivary glands• Sensory taste to anterior 2/3 tongueOriginates in the pons19CN VII: Facial Nerve20CN VII: Facial Nerve Testing• Tests:1. Check taste on anterior 2/3 of tongue by having patient taste sugar, salt, sour and bitter2. Check symmetry of facial muscles:• Close eyes, smile, whistle, puff out cheeks (make funny faces)3. Check tearing with ammonia fumes21CN VII: Facial Nerve• Symptoms of nerve damage:• Mild weakness to total paralysis of facial muscles (may include twitching),• Drooping eyelid• Drooping corner of the mouth• Drooling or dry mouth• Impairment of taste• Excessive tearing in the eye or dry eye22CN VII: Facial Nerve Injury (Bell’s Palsy)Paralyzed facial muscles Patients can still feel their face because sensory is supplied by the trigeminal nerveInjured sideNormal side23CN VIII: Vestibulocochlear• Function: Sensory• Vestibular system for balance & equilibrium• Cochlea for hearing•Tests:• Auditory component of the nerve: • Hearing test• Vestibular control of balance and movement: • Romberg test (tests equilibrium)Originates in the medulla24CN VIII: Vestibulocochlear Tests• Simple hearing test:• Rub fingers together near the ear and ask “right or left” If there is lateralization (hearing louder on one side) there is a problem• Other hearing tests:• Performed by an audiologist with special equipment to determine tones, frequencies and degree of hearing loss25CN VIII: Vestibulocochlear TestsRomberg Test• Have patient stand with arms at side and feet together• Have patient stand with their eyes closed• Stand close to prevent falls• Normally, they