Cranial Nerves Flashcards
Cranial Nerve Locations
Midbrain: CN III-IV
Pons: CN V-VIII
Medulla: CN IX-XII
Cell Bodies
Sensory: myelinated by schwann cells (PNS) EXCEPT FOR CN I-II (CNS)
Motor: nuclei in brainstem
CN I Exit Foramina
Cribriform plate
CN II Exit Foramina
Optic canal
CN III & IV & VI Exit Foramina
Superior orbital fissure
CN V Exit Foramina
V1: superior orbital fissure
V2: foramen rotundum
V3: foramen ovale
CN VII & VIII Exit Foramina
Auditory canal
CN IX & X & XI Exit Foramina
Jugular foramen
CN XII Exit Foramina
Hypoglossal foramen
CN I
Olfactory (sensory)
-smell (olfactory cortex: amygdala, parahippocampal gyrus, uncus, insula)
-only sensory input that reaches cortex before thalamus
1) cover 1 nostril and smell different
CI
Anosmia: loss of smell
-avulsion of olfactory fibers
CN II
Optic (sensory)
-visual acuity (visual cortex: occipital lobe)
Optic Nerve: from eyes
Optic Chiasm: crossing
Optic tract: to visual cortex
1) consensual contralateral light response (midbrain)
2) eye chart
CI
Homonymous Hemianopsia: damage in contralateral visual path results in ipsilateral 1/2 blindness
CN III
Oculomotor (motor)
-eye and eyelid movement
1) eye movements except lateral and down/in
2) consensual ipsi light response
3) cover eye and pupillary constriction of contra
CI
External Strabismus: ipsilateral eye fixed in abd
Ipsilateral ptosis: paralysis of upper eyelid
Diplopia: double vision
Mydriasis: Ipsilateral pupuil fully dilated
CN IV
Trochlear (Motor)
-ipsilaterally eye movement (down and in)
-only CN that exits dorsum of brainstem
1) H test
CI:
Cannot down and in
-double vision
-difficulty reading
-head tilt to opposite side
CN V
Trigeminal (Both)
V1: Opthalamic (sensory)
V2: Maxillary (sensory)
V3: mandibular (both)
Motor: clench jaw and feel masseter and temporalis
Sensory: check in forehead (ophamalic), checks (maxillary), and jaw (mandibular)
CI:
Corneal Blink Reflex
-tactile sensation on cornea
Trigeminal Neuralgia
-sharp pain in face
CN VI
Abducens (motor)
-lateral eye movements
-H test
CI:
-double vision
CN VII
Facial (both)
Motor: facial expression and salivary, stapedius of ear
Sensory: tongue and pharynx
Parasympathetic: salivary gland
Special Sensation: ant 2/3rd of tongue
Testing
-Motor:
1) smile
2) frown
3) move eyebrows
Sensory:
-close eyes and place sweet/salt on anterior 2/3rds of tongue
CI
Bell’s Palsy
CN VIII
Vestibulocochlear (sensory)
-hearing and vestibular
Hearing:
1) rub fingers together
2) whisper word identification
3) Weber Test: tuning fork on head
4) Rhine Test: tuning fork on mastoid
Vestibular:
1) touch nose then pt finger
2) turn head while looking at thumb
CN IX
Glossopharyngeal (Both)
-Motor: stylopharyngeus
-Parasympathetic: parotid salivary gland, carotid a.
-Sensory: 1/3 pos tongue, soft palate, ear, gag reflex
Sensory:
1) sour/bitter taste on posterior 1/3 tongue
Motor:
1) swallowing
CN X
Vagus (both)
Motor: larynx, pharynx, tongue, gag
Parasympathetic: decrease HR, bronchoconstriction, digesiton
Test
1) saw ah, uvula deviation to strong side
2)Swallowing
3) SCM
CI:
-hoarseness and swallowing difficulties, digestion issues
CN XI
Accessory (motor)
-SCM and trap
-Cell bodies in ventral horn of C1-C4
-travels through foramen magnum and exits jugular foramen
Test
1) shoulder shrug
2) head turning
CN XII
Hypoglossal (motor)
-tongue movements
-swallowing
-speaking
1) stick tongue out, deviates to weak side
CI:
-Dysphagia: difficulty swallowing
-Dysarthria: poor control of speech muscles
-LMN: flaccid tongue, deviates to weak
-UMN: tongue deviates to strong side
Stages of Swallowing: Oral
Food in mouth, close lips: VII
Mastication: V, VII, XII
Larynx closes: X
Swallow reflex: IX
Stages of Swallowing: Pharyngeal/Laryngeal/Esophageal
Soft palate rises, epiglottis covers trachea, peristalsis in esophagus : X
