Cranial Nerves

Question 1

Cranial Nerve Locations

Answer 1

Midbrain: CN III-IV
Pons: CN V-VIII
Medulla: CN IX-XII

Question 2

Cell Bodies

Answer 2

Sensory: myelinated by schwann cells (PNS) EXCEPT FOR CN I-II (CNS)

Motor: nuclei in brainstem

Question 3

CN I Exit Foramina

Answer 3

Cribriform plate

Question 4

CN II Exit Foramina

Answer 4

Optic canal

Question 5

CN III & IV & VI Exit Foramina

Answer 5

Superior orbital fissure

Question 6

CN V Exit Foramina

Answer 6

V1: superior orbital fissure
V2: foramen rotundum
V3: foramen ovale

Question 7

CN VII & VIII Exit Foramina

Answer 7

Auditory canal

Question 8

CN IX & X & XI Exit Foramina

Answer 8

Jugular foramen

Question 9

CN XII Exit Foramina

Answer 9

Hypoglossal foramen

Question 10

CN I

Answer 10

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

Question 11

CN II

Answer 11

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

Question 12

CN III

Answer 12

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

Question 13

CN IV

Answer 13

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

Question 14

CN V

Answer 14

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

Question 15

CN VI

Answer 15

Abducens (motor)
-lateral eye movements
-H test

CI:
-double vision

Question 16

CN VII

Answer 16

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

Question 17

CN VIII

Answer 17

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

Question 18

CN IX

Answer 18

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

Question 19

CN X

Answer 19

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

Question 20

CN XI

Answer 20

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

Question 21

CN XII

Answer 21

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

Question 22

Stages of Swallowing: Oral

Answer 22

Food in mouth, close lips: VII
Mastication: V, VII, XII
Larynx closes: X
Swallow reflex: IX

Question 23

Stages of Swallowing: Pharyngeal/Laryngeal/Esophageal

Answer 23

Soft palate rises, epiglottis covers trachea, peristalsis in esophagus : X