Cranial Nerves

Question 1

OOOT TAFAG VAH components

Answer 1

• Olfactory
• Optic
• Ocularmotor
• Trochlear
• Trigeminal
• Abducens
• Facial
• Auditory and Vestibular
• Glossopharyngeal
• Vagus
• Accessory (Spinal)
• Hypoglossal

Question 2

Cranial Nerve Classifications

Answer 2

• Information types:
  General vs. Specific
• Muscle types:
  Skeletal vs. Visceral
  * Fiber types:
  Afferent vs. Efferent

Question 3

Special Information Type Definition

Answer 3

• Innervation of specialized systems only found in a small part of the body
• e.g. vision instead of pain

Question 4

Skeletal Information Type Definition

Answer 4

Motor and sensory functions in muscles attached to bones

Question 5

Visceral Information Type Definition

Answer 5

Motor and sensory functions for vital organs

Question 6

Cranial nerves with Afferent fibers

Answer 6

I, II, VIII

Question 7

Cranial Nerves with Efferent Fibers

Answer 7

III, IV, VI, XI, XII

Question 8

Cranial Nerves with both Afferent and Efferent fibers

Answer 8

V, VII, IX, X

Question 9

CN I

Answer 9

• Olfactory
• Related to sense of smell
• Receptors are replaced every 30-60 days
• Degeneration of olfactory cells and fibers can occur with age or damage (Unilateral or bilateral)

Question 10

Anosmia

Answer 10

Complete loss of smell

Question 11

Hyposmia

Answer 11

Less sense of smell

Question 12

Hyperosmia

Answer 12

Overly strong sense of smell

Question 13

CN II

Answer 13

• Optic
• Carries visual information from the eyes
• Goes from retina through the lateral geniculate body to the visual cortex
• Result of damage highly dependent on location of lesion
• Mix of ipsilateral and contralateral
• Based on halves of visual field: left side of vision goes to the right and vice versa

Question 14

CN III

Answer 14

• Oculomotor
• Controls:
  
  • Most of the muscles for moving the eyes
  • Parasympathetic pupillary constriciton
  • Lens adjustments for focusing on nearby objects

Question 15

CN IV

Answer 15

• Trochlear
• Associated with the position of the eyes

Question 16

CN V

Answer 16

• Trigeminal
• Contains sensory nerve for face, head, oral/orbital cavities
• Motor nerve for muscles of mastication
• Gives a lot of information

Question 17

CN V Damage

Answer 17

Results in:
* Ipsilateral loss of sensation (face, tongue, teeth, mouth, gum, and cavities)
* Trigeminal neuralgia: incredibly painful sensation, generally triggered by light touches to the face (e.g. breeze)
* Bilateral jaw paralysis

Question 18

CN VI

Answer 18

-Abducens
-Involved in lateral movement of the eye (side to side)

Question 19

Controlling Eye Movement

Answer 19

-The brainstem gaze centers coordinate the activity across the oculomotor, trochlear, and abducens nerve
-All work together for desired eye movement

Question 20

CN VII

Answer 20

-Facial

-Controls muscles involved in:
>Facial expression
>Stapedial reflex (happens within middle ear in response to long-ish loud sounds. This tightens the middle ear to reduce the response to the sound)

-Mediates taste sensation in the anterior 2/3 of the tongue

Question 21

CN VIII

Answer 21

-Auditory and Vestibular (aka vestibularcochlear)

-Related to hearing and balance

-The auditory and vestibular portions that make up this cranial nerve are often discussed as separate nerves
-One nerve from the cochlea and one nerve from the semicircular canals
-These nerves later join up

Question 22

CN VIII Damage

Answer 22

-Depending on where the lesion occurs, can affect:
>Hearing
>Balance
>Both

-However, the vestibular nerve is not the only nerve carrying balance information

-Visual information from the optic nerve helps with balance

Question 23

CN IX

Answer 23

-Glossopharyngeal

-Touch, pain, tension, and temperature sensations from pharynx, tonsils, eustachian tube, middle ear cavity, and soft palate

-Taste sensation for posterior 1/3 of tounge

-Swallowing
-Talking

Question 24

CN IX Damage

Answer 24

Results in:
-Swallowing difficulties
-Loss of taste sensation from ipsilateral posterior third of tongue
-Loss of gag reflex

Question 25

CN X

Answer 25

-Vagus
-Regulates:
>Cardiac muscles
>Stomach
>Esophagus and pharynx (swallowing)
>Larynx (phonation)

Question 26

CN XI

Answer 26

-Spinal Accessory
-Involved in:
>Head rotation
>Shoulder elevation (shrugging)

Question 27

CN XI Damage

Answer 27

Results in impaired ability to:
-Rotate the head laterally
-Raise the shoulders

-Damage patterns result in loss of general functioning of nerve

Question 28

CN XII

Answer 28

-Hypoglossal
-Involved in tongue movement
-Has unilateral innervation (symptoms can affect only one side of tongue)

Question 29

CN XII Damage

Answer 29

Can result in:
-ipsilateral paralysis of the tongue causing it to be wrinkled and atrophy
-Tongue deviation to side of lesion
-Chewing difficulty

-Bilateral damage can result in profound difficulty swallowing, eating, and speaking

Question 30

Cranial Nerves Relationship with motor and sensory systems

Answer 30

-It is not the case that there is a one-to-one relationship between cranial nerves and motor or sensory systems

-e.g. Eyes are moved by oculomotor, abducens and trochlear

-e.g. Tongue has special system of taste: Posterior 1/3 is CN IX, Anterior 2/3 is CN VII. Also has general somatic sensation: Posterior 1/3 is CN IX, Anterior 2/3 is CN V

-e.g. Palatal and pharyngeal muscle: some by vagus, some by trigeminal, some by glossopharyngeal

Question 31

Area of body that Cranial Nerves control

Answer 31

Sensorimotor information from the shoulders up