Mod5-Obj10: Cranial nerves

Question 1

Cranial nerves

Answer 1

• 12 pairs of nerves that originate directly from the brain (forebrain and brainstem)
• Innervate structures of the head and neck, and visceral organs (names accordingly)
• Can be classified as sensory nerves, motor nerves or mixed nerves

Question 2

12 cranial nerves

Answer 2

1. ) Olfactory nerve (I)
2. ) Optic nerve (II)
3. ) Oculomotor nerve (III)
4. ) Trochlear nerve (IV)
5. ) Trigeminal nerve (V)
6. ) Abducens nerve (VI)
7. ) Facial nerve (VII)
8. ) Vestibulocochlear nerve (VIII)
9. ) Glossopharyngeal nerve (IX)
10. ) Vagus nerve (X)
11. ) Accessory nerve (XI)
12. ) Hypoglossal nerve (XII)

Question 3

Olfactory nerve (I)

Answer 3

Sensory function:
-Smell
Motor function:
-None

Question 4

Optic nerve (II)

Answer 4

Sensory function:
-Vision
Motor function:
-None

Question 5

Oculomotor nerve (III)

Answer 5

Sensory function:
-None
Motor function:
-Eyeball movement, pupil constriction, lens shape

Question 6

Trochlear nerve (IV)

Answer 6

Sensory function:
-None
Motor function:
-Eyeball movement

Question 7

Trigeminal nerve (V)

Answer 7

Sensory function:
-Facial sensation (touch, pain, temp)
Motor function:
-Mastication (chewing)

Question 8

Abducens nerve (VI)

Answer 8

Sensory function:
-None
Motor function:
-Eyeball abduction

Question 9

Facial nerve (VII)

Answer 9

Sensory function:
-Taste
Motor function:
-Facial expression, salivation, tears

Question 10

Vestibulocochlear nerve (VIII)

Answer 10

Sensory function:
-Hearing and balance
Motor function:
-Minor

Question 11

Glossopharyngeal nerve (IX)

Answer 11

Sensory function:
-Taste
Motor function:
-Pharynx (some tongue) movement, swallowing, salivation

Question 12

Vagus nerve (X)

Answer 12

Sensory function:
-Taste
-relays information from: baroreceptors, chemoreceptors, proprioreceptors
Motor function:
Heart rate, breathing, swallowing, digestive activities

Question 13

Accessory nerve (XI)

Answer 13

Sensory function:
Muscle proprioception
Motor function:
Head and neck movements

Question 14

Hypoglossal nerve (XII)

Answer 14

Sensory function:
Muscle proprioception
Motor function:
Tongue movement, chewing, swallowing, speech

Question 15

Cranial nerves that include both somatic and parasympathetic motor innervation

Answer 15

CN III, VII, IX and X

Question 16

Only cranial nerve to extend beyond the head/neck region is the…

Answer 16

Vagus nerve (X)

Question 17

Motor innervation of the Vagus nerve (X)

Answer 17

• Parasympathetic motor to visceral organs=heart, lungs, abdominal organs
• Somatic motor to pharynx and larynx

Question 18

Sensory innervation of the Vagus nerve (X)

Answer 18

• Thoracic and abdominal viscera
• Baroreceptors
• Chemoreceptors
• Taste buds
• Proprioreceptors (pharynx and larynx)

Question 19

Cranial nerve reflexes

Answer 19

Rapid, involuntary motor responses generated by the brain in response to a stimulus

Question 20

Cranial nerve reflexes provide simple diagnostic tests to assess:

Answer 20

1. ) The condition of cranial nerves

2. ) Processing centres in the brain

Question 21

Corneal reflex

Answer 21

Stimulus:
-Contact with corneal surface
Cranial nerves involved:
-CN V 
-CN VII
Response: 
Blinking of eyelids

Question 22

Auditory/startle reflex

Answer 22

Stimulus: 
-Loud noise 
Cranial nerves involved:
-CN VIII 
-CN III,IV,VI
-CN XI
Response:
-Eyelids and/or head movements

Question 23

Pupillary (consensual light) reflex

Answer 23

Stimulus:
-Light striking photoreceptors of the eye
Cranial nerves:
-CN II
-CN III
Response:
-Constriction of pupils

Question 24

Nerve repair

Answer 24

If damaged, the sensory and motor axons within the peripheral nerve can regenerate providing:

• The cell body is intact
• Schwann cells the produce myelin are active
• Severed axon ending are close together