1. “On Old Olympus Towering Tops A…” Andrea Gianniny Eden Treadway
CRANIAL NERVES I-VI
“On Old Olympus Towering Tops A…”
Andrea Gianniny
Eden Treadway

2. Brief Review CNs : from brain pass through foramina magnum of skull
I-XII from ascending – descending
CNs 1 & II attach to forebrain
I- telencephalon
II- diencephalon
Other 10 to brainstem
Primarily serve head/neck structures
Vagus (X) extends to abdomen

3. Number Name Sensory/Motor/Both I Olfactory On Some II Optic Old Say
III
Oculomotor
Olympus
Money IV
Trochlear
Towering
Matters V
Trigeminal
Tops
But VI
Abducens A My
VII
Facial
Finn
Brother
VIII
Auditory
And
Says IX
Glossopharyngeal
German
Big X
Vagus
Viewed
Brains XI
Spinal Accessory
Matter
XII
Hypoglossal
Hops
Most

5. I - Olfactory Sensory nerve of smell
Function: transduce odor molecules
Cortical olfactory regions: responsible for olfactory awareness and
Limbic olfactory connections: responsible for integrating smell with emotions
Connections with hypothalamus play role in feeding behavior.
Formed by unmyelinated axons, terminates into two olfactory bulbs located in the inferior surface of the frontal lobe

6. Clinical Conditions - I
Damage: deviations in ability to smell
Anosmia/hyposmia- Reduction or loss of ability to smell
Hyperosmia- Abnormally acute sensation of smell

7. II - Optic Sensory nerve of vision
Optic nerve endings receive light energy in the form of nerve potentials produced by photoreceptor cells in the retina.
Path: axons of the Optic Nerve travel until the optic chiasm and then as the optic tract. The optic tract then terminates in the Lateral Geniculate Body of the thalamus. There, the optic radiations travel to primary visual cortex.

8. Clinical Conditons - II
Ipsilateral blindness:
lesion to optic nerve
Bitemporal hemianopsia:
chiasmatic lesion
Unilateral homonymous hemianopsia:
post chiasmatic lesions close to lateral geniculate body
 Upper & Lower homonymous
quadrantopsia:
lesions distal to the geniculate ganglion

9. III - Oculomotor Motor nerve
Innervates four of six extrinsic eye muscles
Form & Function: composed of two components
Somatic: Innervates the four extrinsic eye muscles & levator superioris, which is responsible for movement of eye lids.
Visceral: innervates the intrinsic ocular eye muscles and controls parasympathetic functions including light reflex (constriction of pupils) and accommodation- convergence (modification of lens for near vision)
CN III is one of only four CNs that are involved in parasympathetic functions (along with VII, IX, and X)

10. Clinical Conditions - III
External Opthalamoplegia: Paralysis of extrinsic eye muscles and levator superiorsis.
Lateral Striabismus: deviation of ipsi eye to the lateral side
May result in diplopia (double vision)
Ptosis: eye lid drooping
Internal Opthalamoplegia: Paralysis of intrinsic muscles
Mydriasis: permanent dilation of pupil

11. Mydriasis

12. IV - Trochlear Motor Eye muscle movement (III, IV, & VI)
Innervation: extrinsic muscle
Superior oblique
Action: abducts and depresses eyeball
Moves eye outward and down
Only CN that exits posterior side of brainstem

13. Clinical Conditions - IV
Damage: difficulty looking down and out
Also, eye fixed in upward, medial gaze

14. VI - Abducens Motor Innervation: extrinsic eye muscle Lateral rectus
Action: abducts eyeball horizontally
Runs long intracranial course therefore more susceptible to damage

15. Clinical Conditions - VI
Damage: medial strisbismus (because medial rectus [CN III] is unopposed) which in turn may cause diplopia
Medial strasbismus: affected eye turns medially
Diplopia: double vision
Medial Longitudinal Fasciculus – brainstem tract that helps communication between CNs III, IV, & VI and vestibular system and neck muscles
Coordinates eye muscles for gaze control and head position with eye movements
doll’s eye reflex

16. Damage to CN VI –
Medial strabismus

17. V - Trigeminal Largest CN Mixed Sensory innervation: from face
Motor innervation: to chewing muscles
Sensory & motor components for Jaw Jerk Reflex - lesion causes exaggerated reflex
3 branches (tri)
V1. Opthalamic nerve (sensory)
V2. Maxillary nerve (sensory)
V3. Mandibular nerve (sensory and motor)

19. V – Trigeminal (cont.) Action: Sensory:
cutaneous (touch, pain, temperature) and…
proprioceptive (awareness of relative muscle movement) sensations from the:
face, head, oral and nasal cavities
Sinuses and teeth
Anterior 1/3 of tongue
Anterior half of pinna, external auditory meatus, and external surface of TM
Motor: controls muscles of mastication (chewing) and speech production, tensor veli palatini (soft palate) and tensor tympani (middle ear muscle)
CN V: controls muscles involved in chewing but NOT facial expressions

20. V – Trigeminal (cont.)
Mandibular nerve: only carries general sensory sensations from mouth, NOT taste
(e.g. touch/position, pain/temperature)
Taste fibers from anterior 2/3 of tongue carried by lingual nerve then chorda tympani (branch of CN VII)
Taste fibers from posterior 1/3 and pharynx carried by branches of CNs VII, IX, and X

21. Clinical Testing - V
Sensory: lightly touch parts of pt’s face with cotton or blunt object
Check for sneezing reflex and corneal reflex (blink in response to touching cornea)
Jaw Jerk Reflex
Motor: check masseter muscle by asking pt to bite down hard
Ask pt to open mouth against resistance at base of chin

22. Clinical Conditions - V
Damage to Sensory portion:
Ipsilateral loss of sensation
Loss of sneezing and blinking reflexes
Trigeminal Neuralgia
Sudden intense pain in eyes, lips, nose, scalp, forehead, and jaw
Nerve severing in rare cases to treat

23. Clinical Conditions - V
Damage to Motor portion:
Ipsilateral muscles of mastication paralyzed
Absent Jaw Jerk reflex, muscle tics/twitching
Dysarthria – paralyzed mandible and soft palate cause misarticulations

24. Clinical Conditions - V
Wallenberg Syndrome:
Believed to be stroke involving Posterior Inferior Cerebellar Artery [PICA]
Loss of pain/temperature sensation from
Ipsilateral (same) side of face
Contralateral (opposite) side of body
Reason: the ascending spinothalamic tract in the medulla carries pain/temp info from contralateral side of body is adjacent to descending tract of CN V which carries pain/temp info from ipsilateral side of face
A stroke cutting off blood supply in this area (e.g. clot in PICA) destroys both tracts

25. Questions! At what point do the CNs pass through the skull? a. medulla
b. jugular foramina
c. foramina magnum
d. brainstem

26. 10 of the 12 CNs originate where?
a. diencephalon
b. brainstem
c. cerebellum
d. medulla

27. Of the first 6 cranial nerves, which is the only mixed nerve?
a. Trochlear
b. Oculomotor
c. Abducens
d. Trigeminal

28. Which cranial nerve exits the brainstem posteriorly?
a. Vagus
b. Trochlear
c. Trigeminal
d. Spinal Accessory

29. This cranial nerve innervates an extrinsic eye muscle (superior oblique) and is responsible for abducting and depressing the eyeball.
a. CN II
b.CN III
c. CN IV
d. CN VI

30. This cranial nerve innervates an extrinsic eye muscle (lateral rectus) and is responsible for abducting the eyeball horizontally.
a. CN II
b. CN III
c. CN IV
d. CN VI

31. Damage to the Abducens nerve (VI) will result in what kind of damage?
a. medial strabismus
b. lateral strabismus
c. Wallenberg Syndrome
d. hemianopsia (blindness in half of visual field)

32. is an important tract in the brainstem that facilitates communication between CNs III, IV, and VI as well as the vestibular system and neck muscles. This tract also coordinates muscles for the doll’s eye reflex.
a. Medial Longitudinal Fasciculus
b. Spinothalamic tract in medulla
c. Pyramidal tract
d. Lateral Corticospinal Tract

33. The largest cranial nerve is .
a. CN IV
b. CN V
c. CN X
d. CN XII

34. CN controls muscles of mastication as well as the tensor veli palatini and tensor tympani muscles involved in speech production.
a. CN X
b. CN VII
c. CN V
d. CN VI

35. A rare condition with symptoms of intense pain in a patient’s face (eyes, lips, nose, jaw, etc.) is known as
a. PICA
b. Occipital Neuraligia
c. Wallenberg Syndrome
d. Trigeminal Neuralgia

36. What branch of the Trigeminal nerve accounts for its motor functions?
a. Opthalamic
b. Mandibular
c. Maxillary
d. Facial

37. Wallenberg Syndrome is a condition characterized by loss of pain/temperature sensation from the side of the body and the side of the face.
a. ipsiliateral; contralateral
b. ipsiliateral; ipsilateral
c. contralateral; contralateral
d. contralateral; ipsilateral

38. The sensory portion of this cranial nerve carries cutaneous and proprioceptive sensations from the anterior 1/3 of the tongue and the anterior half of the pinna, external auditory meatus, and external surface of the TM.
a. CN V
b. CN VII
c. CN IX
d. CN IV

39. A condition that causes a reduction or loss of the ability to smell is known as _____________.
a. Hyperosmia
b. Neuralgia
c. Anosmia
d. Wallenberg Syndrome

40. CN ___ innervates four of the six extrinsic eye muscles.
a. CN VI
b. CN II
c. CN III
d. CN IV

41. A lesion to CN ____ can cause ipsilateral blindness.
a. CN I
b. CN II
c. CN III
d. CN IV

42. Sensory endings of CN ____ are responsible for responding to noxious sensations, such as those associated with mace spray, onions, and mustard oil.
a. CN V
b. CN IV
c. CN II
d. CN I

43. Connections of Cranial Nerve ___ with the hypothalamus play an important role in feeding behavior.
a. CN III
b. CN II
c. CN IV
d. CN I

44. The visceral portion of CN ____ controls parasympathetic functions such as light reflex and accommodation- convergence reflex.
a. CN IV
b. CN III
c. CN I
d. CN II

45. Which of the following nerves do NOT serve parasympathetic functions of the autonomic system?
a. CN III
b. CN IX
c. CN II
d. CN VII

46. Paralysis of the extrinsic eye muscles and levator superiorsis is known as ____________________.
a. External Opthalamoplegia
b. Internal Opthalamoplegia
c. External Neuralgia
d. Internal Neuralgia

47. All of the following are Motor or Mixed nerves EXCEPT:
a. CN III
b. CN IV
c. CN II
d. CN V

48. Lateral striabismus caused from a lesion to CN III can cause double vision, which is formally known as:
a. Mydriasis
b. Bitemporal hemianopsia
c. Ipsilateral blindness
d. Diplopia

49. Where are the two olfactory bulbs, where CN I terminates, located?
a. Superior surface of Temporal lobe
b. Inferior surface of Frontal lobe
c. Inferior surface of Occipital lobe
d. Superior surface of Occipital lobe