Neuro-Ophthalmology

Question 1

where is the oculomotor nucleus located?

Answer 1

dorsal midbrain at the level of the superior colliculus

Question 2

where does the oculomotor nerve exit the brainstem?

Answer 2

through interpeduncular fossa, passing between posterior cerebral artery and superior cerebellar artery
then travels through lateral wall of cavernous sinus to enter orbit via superior orbital fissure

Question 3

what other fibres accompany the oculomotor nerve?

Answer 3

parasympathetic fibres originating from Edinger-westphal nucleus which innervates sphincter pupillae and ciliary muscles (efferent limb of pupillary light reflex)

Question 4

where is the trochlear nerve nuclei located?

Answer 4

in the midbrain at the level of the inferior colliculus

Question 5

describe the path of the trochlear nerve?

Answer 5

passes through lateral wall of cavernous sinus inferior to the oculomotor nerve and enters orbit via superior orbital fissure

Question 6

3 unique characteristics of trochlear nerve?

Answer 6

only CN that exits dorsally from brainstem
smallest CN
longest intracranial course

Question 7

describe the path of the abducens nerve?

Answer 7

nucleus in pontine tegmentum ventral to 4th ventricle
travels through the cavernous sinus lateral to internal carotid
then enters orbit via superior orbital fissure

Question 8

through which cranial foramen does each CN exit the skull?

Answer 8

CN1 = cribiform plate
CN2 = optic canal
CN3 = SOF
CN4 = SOF
CN5-1 = SOF
CN5-2 = foramen rotundum
CN5-3 = foramen ovale
CN6 = SOF
CN7 = internal auditory meatus
CN8 = internal auditory meatus
CN9 = jugular foramen
CN10 = jugular foramen
CN11 = jugular foramen
CN12 = hypoglossal canal

Question 9

describe the pupillary light reflex?

Answer 9

light enters eye > travels along optic nerve > exits optic tract to the ipsilateral pretectal nucleus in midbrain > nucleus projects bilateral signals to both Edinger-westphal nuclei > pre-ganglionic parasympathetic fibres from Edinger Westphal travel along oculomotor nerve then exit to synapse with post-ganglionic neurones in ciliary ganglion > parasympathetics from ciliary ganglion carried via short ciliary nerves to innervate ciliary muscle and sphincter pupillae

Question 10

what are the 3 components of the accommodation reflex?

Answer 10

increase lens curvature (ciliary muscle contracts causing relaxation of suspensory ligaments)
constriction of pupils (activation of sphincter pupillae)
eye convergence (contraction of medial recti muscles)

Question 11

pathway of pupillary dilation?

Answer 11

//