Anatomy
Name the bones of medial wall of the orbit
Maxillary
Lacrimal
Ethmoid
Sphenoid
(My Little Eye Sits)
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What nerve innervates the lower eyelid
Trigeminal - maxillary - V2
Which muscle constricts the pupil
Sphincter pupillae
parasympathetic innervation
Name the extraocular muscles
> levator palpabrae superioris
superior rectus, inferior rectus, medial rectus, lateral rectus
>superior oblique, inferior oblique
What happens to the lens in the accomodation reflex
Lens becomes more convex and thicker to increase its refractive (focusing) power
What movement is associated with the lateral rectus
abduction
What drains the aqueous humour into venous circulation
Scleral venous sinus
What is hyperopia
Long sighted
Eye is short and focuses near objects dehind the retina
corrected using a convex external lens
What are the cells of the retina
(vitrous humor)
Ganglion cell > Bipolar cell > Neural retina (cone & rods)> pigmented epithelium (light absorbing cells next to choroid)
What nerve is involved in the efferent limb of the corneal reflex
Facial Nerve (CN VII)
Orbicularis oculi contracts to close the eyelids
There is a cranial nerve lesion on the abducesns nerve, what are the clinical findings
Unable to move eye laterally - cant abduct
Which blood vessel (and its pathway) supplies the retina
Central retinal artery from the opthalmic artery, from the internal carotid artery
What eye 'condition' ie eyesight issue is corrected using a concave external lens
Myopia
Short sightedness
Eye is long and objects focussed in front of the retina
What makes the fovea have higher acuity than the peripheral retina
Better ratio of cells to ganglion cells
Fovea: one ganglion = one cone + one bipolar cell
Periphery: One glanglion = multiple cone/rods + multiple bipolar cells
Why does the pupillary light reflex cause constriction in BOTH eyes
Neurons from the pretectal area transmit to BOTH Edinger-Westphal nuclei of midbrain
Explain what happens to the ciliary body when looking at a distant object
Ciliary muscle relaxes
Zonular fibres are taut
lens stretches and becomes less convex
What nerve innervates the superior tarsal muscle
sympathetic nervous system
involuntarily elevates upper eyelid
What is presbyopia
loss of accomodation with age = difficulty reading
Where is the lateral geniculate nucleus
Thalamus
Explain Meyer's Loop
Superior visual field (contralateral superior quadrant) > inferior retina > through temporal lobe > lower bank of the calcarine sulcus
What movement does the oculomotor mucleus in midbrain cause during the accomodation reflex
medial rectus contracts so eyes converge towards the nose
Which motor nerves involved in vision decussates
trochlear Nerve (CN IV)
emerges from posterior aspect of midbrain and decussates
Where would the lesion be for a complete left homonymous heminopia ◐◐
Right optic tract after the optic chiasm