2k. Cranial Nerves

Question 1

Cranial Nerve Names

Answer 1

I = olfactory
II = optic
III = oculomotor
IV = trochear
V = trigeminal
VI = abducens
VII - fascial
VIII = vestibulocochlea
IX = glossopharyngeal
X = vagus
XI = accessory
XII = hypoglossal

Question 2

Cranial Nerve I

- Skull Exit

Answer 2

Cribriform plate through the mesethmoid bone

Question 3

Cranial Nerve II

- Skull Exit

Answer 3

Optic foramen

Question 4

Cranial Nerve III

- Skull Exit

Answer 4

Orbital fissure

Question 5

Cranial Nerve IV

- Skull Exit

Answer 5

Orbital fissure

Question 6

Cranial Nerve V

- Skull Exit

Answer 6

V1 = orbital fissure and rostral alar foramen (round foramen)

V2 = rostral alar foramen (round foramen)

V3 = Oval foramen

Question 7

Cranial Nerve VI

- Skull Exit

Answer 7

Orbital fissure

Question 8

Cranial Nerve VII

- Skull Exit

Answer 8

Stylomastoid foramen

Question 9

Cranial Nerve VIII

- Skull Exit

Answer 9

Internal auditory meatus

Question 10

Cranial Nerve IX

- Skull Exit

Answer 10

Jugular foramen

Question 11

Cranial Nerve X

- Skull Exit

Answer 11

Jugular foramen

Question 12

Cranial Nerve XI

- Skull Exit

Answer 12

Jugular foramen

Question 13

Cranial Nerve XII

- Skull Exit

Answer 13

Hypoglossal foramen

Question 14

Brainstem Nuclei

- Motor and Sensory Positions

Answer 14

• Motor nuclei are medial

- Sensory nuclei are lateral

Question 15

Brainstem Nuclei

- Sensory Nuclei Divisions

Answer 15

• Somatic sensory neurones are lateral
• Special sense sensory neurones are in the middle
• Visceral sensory neurones are medial

Question 16

Brainstem Nuclei

- Motor Nuclei Divisions

Answer 16

• Autonomic/visceral motor neurones are lateral
• Pharyngeal arch motor neurones are in the middle
• Somatic motor neurones are medial

Question 17

Brainstem Nuclei

- Trigeminal nucleus

Answer 17

Cranial nerves III, IV and VI have no ganglia despite containing sensory proprioceptive fibres bringing information about eye position back to the brain.

They have embedded in the trigeminal nucleus of the brainstem as the mesenchephalic nucleus.

Therefore these cells are neural crest derived, not neural ectoderm like the true brainstem

Question 18

Horner’s Syndrome

- Cause

Answer 18

Loss of sympathetic innervation of the head, caused by damage at any point on the sympathetic pathway.

Often caused by middle ear infection damaging the sympathetic nerves running through it

Question 19

Horner’s Syndrome

- 6 Clinical Signs

Answer 19

1. Mitosis (pupil constriction)
   - Loss of sympathetic innervation of the circumferential dilatory muscles in the iris
2. Ptosis (lowering of the upper eyelid)
   - Loss of sympathetic innervation to the deep leaf of elevator palpebral superioris
3. Enophthalmia (eyeball sinking posteriorly)
   - Loss of sympathetic innervation to the periorbital smooth muscle and fascia
4. Conjunctival vascular engorgement
   - Loss of sympathetic vasoconstrictive innervation to the eye is lost
5. Reduced intraocular pressure
6. Horses sweat ventral to the eye

Question 20

Horner’s Syndrome

- Characteristics

Answer 20

Unilateral

Non-painful

Question 21

Feline Dysautonomia Syndrome

- Cause

Answer 21

Loss of parasympathetic innervation to the head

Question 22

Feline Dysautonomia Syndrome

- Clinical Sign

Answer 22

1. Mydriasis (pupil dilation)

- Loss of parasympathetic innervation of the radial constrictory muscles in the iris