Cranial Nerve Pathways & Reflexes

Question 1

6 locations of the visual pathway

Answer 1

1. optic nerve
2. optic chiasm
3. optic tract
4. lateral geniculate body
5. optic radiations
6. visual cortex

Question 2

2 types of visual protective reflexes

Answer 2

1. corneal blink reflex

2. pupillary light reflex

Question 3

where can rods & cones be found?

Answer 3

retina

Question 4

1st neuron in optic nerve pathway

Answer 4

bipolar cell (special sense)

Question 5

2nd neuron in optic nerve pathway

Answer 5

ganglion cell

Question 6

the 4 steps of the visual pathway

Answer 6

1. ganglion cells synapse in Lateral Geniculate Nucleus (in thalamus)
2. 3rd neuron travels via optic radiation to the:
3. banks of calcerine sulcus (primary visual cortex, occipital lobe)
4. collaterals to midbrain (superior colliculus, pretectal area)

Question 7

3 steps in the lateralisation of the visual field occurs at the optic chiasm

Answer 7

1. the lateral (temporal) visual field projects onto the medial (nasal) retina
2. fibres from the nasal retinae decussate at the optic chiasm
3. the optic tract carries information from the contralateral visual field

Question 8

the 2 types of superior-inferior retinotopy

Answer 8

1. lower visual field travels through the parietal optic radiation (stimulates superior retina)
2. upper visual field travels via the Meyer loop through the temporal lobe (stimulates inferior retina)

Question 9

the 3 cranial nerves that control the muscles of the eye

Answer 9

1. oculomotor III
2. trochlear IV
3. abducens VI

Question 10

oculomotor III somatic motor nucleus

Answer 10

tegmentum of rostral midbrain
near midline
anterior to cerebral aqueduct & PAG
rostral end of medial longitudinal fasciculus (MLF)
fibres travel anteriorly to emerge in interpeduncular fossa

Question 11

oculomotor III parasympathetic nucleus

Answer 11

Edinger-Westphal nucleus
posterior to somatic nucleus
in periaqueductal grey (PAG)
preganglionic axons travel with somatic axons, exit at ciliary ganglion

Question 12

oculomotor parasympathetic axons

Answer 12

located superficially to in the CNIII nerve

more susceptible to compression

Question 13

where is the pretectal area

Answer 13

rostral to superior colliculus at midbrain/diencephalon junction

Question 14

trochlear IV nucleus

Answer 14

midbrain at level of the inferior colliculus
near midline
axons exit dorsally

Question 15

abducens VI nucleus

Answer 15

caudal pons at level of the facial colliculus

near midline

Question 16

what does the abducens nucleus contain?

Answer 16

somatic motor nucleus - neurons innervate lateral rectus

interneurons - coordination of horizontal eye movements