Cranial Nerves

Question 1

What are the 12 cranial nerves?

Answer 1

1 - olfactory
2 - optic
3 - oculomotor
4 - trochlea
5 - trigeminal
6 - abducens
7 - facial
8 - vestibulocochlear
9 - glossopharyngeal 
10 - vagus
11 - spinal accessory 
12 - hypoglossal

Question 2

Which of the cranial nerves are sensory?

Answer 2

1 - olfactory
2 - optic
8 - vestibulocochlear

Question 3

Which of the cranial nerves are motor?

Answer 3

3 - oculomotor
4 - trochlea
6 - abducens 
11 - spinal accessory 
12 - hypoglossal

Question 4

Which of the cranial nerves are mixed?

Answer 4

5 - trigeminal
7 - facial
9 - glossopharyngeal
10 - vagus

Question 5

What is the function of the CNI and where does it exit the skull?

Answer 5

Sense of smell, exits the skull at the cribiform plate of the ethmoid bone

Question 6

What is the function of the CNII and where does it exit the skull?

Answer 6

Vision, exits the skull at the optic canal

Question 7

What is the function of the CNIII and where does it exit the skull?

Answer 7

Eye movements - controls 3 rectus muscles (superior, inferior and medial) and inferior oblique, eye opening (levator palpebrae), pupil constriction, exits the skull at the superior orbital fissure

Question 8

What is the function of the CNIV and where does it exit the skull?

Answer 8

Eye movements - controls superior oblique, exits the skull at the superior orbital fissure

Question 9

What is the function of the CNV and where does it exit the skull?

Answer 9

Sensory: input from the face and inside of mouth
Motor: muscles of mastication and tensor tympani
3 branches, V1 - opthalmic exits the superior orbital fissure
V2 - maxillary exits at foramen rotundum
V3 - mandibular exits at foramen ovale
Motor branch passes on the underside of the ganglion and travels with the mandibular division

Question 10

What is the function of the CNVI and where does it exit the skull?

Answer 10

Eye movements - controls the lateral rectus muscle, exits the skull at the superior orbital fissure

Question 11

What is the function of the CNVII and where does it exit the skull?

Answer 11

Sensory: taste anterior 2/3 tongue, skin behind the ear
Motor: muscles of facial expression (facial nerve proper, 5 branches TZBMC), and stapedius
PS: lacrimal, sublingual and submandibular glands
Exits the skull at the internal acoustic meatus

Question 12

What is the function of the CNVIII and where does it exit the skull?

Answer 12

Hearing and balance (vestibular inputs)

Exits the skull at the internal acoustic meatus

Question 13

What is the function of the CNIX and where does it exit the skull?

Answer 13

Sensory: from tongue (posterior 1/3), pharynx, middle ear and carotid body, taste from posterior 1/3 of tongue
Visceral motor: PS to parotid
Motor: stylopharyngeus
Exits the skull at the jugular foramen

Question 14

What is the function of the CNX and where does it exit the skull?

Answer 14

Mostly autonomic
Motor: soft palate, pharynx, larynx, upper oesophagus and palatoglossus
Visceral motor: pharynx to upper abdomen
Sensory: pharynx, larynx, oesophagus, ear
Exits the skull at the jugular foramen

Question 15

What is the function of the CNXI and where does it exit the skull?

Answer 15

Motor to trapezius and sternomastoid
Nucleus is in the upper 5-6 of cervical spinal cord, enters the cranium via foramen magnum then leaves via jugular foramen

Question 16

What is the function of the CNXII and where does it exit the skull?

Answer 16

Motor to intrinsic and extrinsic tongue muscles, exits at the hypoglossal foramen

Question 17

What is the rule of 4s?

Answer 17

4 nuclei above the pons, 4 in the pons, 4 in the medulla

• 1, 2, 3, 4 are above the pons
• 5, 6, 7, 8 are in the pons
• 8, 9, 10, 12 are in the medulla

Question 18

How do you test the function of the midbrain?

Answer 18

Pupillary light reflex
- sensory input (afferent) to brain from retina is via CNI, motor output (efferent) to sphincter puppillae via EWN (CNIII)

Question 19

How do you test the function of the pons?

Answer 19

Corneal blink reflex

- sensory input (afferent) via CNV1, motor output (efferent) to orbicularis oris via CNVII

Question 20

How do you test the function of the medulla?

Answer 20

Gag reflex

- sensory input (afferent) via CNIX, motor output (efferent) to pharynx via CNX

Question 21

Are cranial nerves upper or lower motor neurons?

Answer 21

LOWER