Orbit, Eye and Lacrimal Apparatus Flashcards
what are the main bones which form the margin of the orbit
frontal, maxilla, zygomatic
what are the openings into the orbit
nasolacrimal canal, inferior and superior orbital fissures, optic canal for optic nerve
what does the optic canal carry
optic nerve and ophthalmic artery
what does the inferior orbital fissure carry
inferior ophthalmic vein
what does the superior orbital fissure carry
ophthalmic, oculomotor, trochlear, abducens and superior ophthalmic vein
what is the retrobulbar fat and what does it do
fatty tissue posterior to eyeball and optic nerve and it supports the eyeball
what are the extraocular muscles
superior rectus, lateral rectus, medial rectus, inferior rectus, superior oblique, lateral oblique
what do the extraorbital muscles do
move the eyeball
what does the optic nerve contain at the centre of the nerve
vascular structure containing retinal artery and retinal vein
what surrounds the optic nerve
cranial meninges
what can trauma to the eye mean for the maxillary sinus
damage to the bony casing can cause contents of the orbit to be displaced into the maxillary sinus
where does the optic chiasm lie
superior and anterior to pituitary gland
where do fibres in the optic tract go
to the visual cortex in the occipital lobe
what is the consequence of a tumour in the pituitary gland on the optic nerve
presses on the optic chiasm and causes issues with vision (tunnel vision)
why can the central retinal artery become occluded
due to transient causes such as amaurosis fugax that leads to painless temporary loss of vision in affected eyes
what causes papilledema
raised intracranial pressure transmitted to the meninges and subarachnoid space around the optic nerve slowing retinal venous drainage via central retinal vein
what is papilledema
swelling of the optic disc making is look fuzzy
what is used as a diagnostic sign for intracranial pressure
papilledema - optic disc looking fuzzy
what happens if there is an injury to the left optic nerve
sight to the eye will be lost but right eye will be fine
what happens if there is an injury to the left side of the optic chiasm
lateral side of each visual field is lost and causes tunnel vision so only the smaller medial side of visual fields still function
what happens if there is an injury to the left optic tract
part of visual fields supplied by this will not work
what is the action of the orbicularis oculi
close eyelids gently or tightly
what innervates the orbicularis oculi
facial nerve
what can malfunction of the facial nerve mean for orbicularis oculi
sagging of lower eyelid, leakage of tears and dry eyes with potential for corneal ulceration
where are tears secreted from
lacrimal gland into conjunctival sacs
where do tears drain to
puncta
canaliculi
lacrimal sac
nasolacrimal duct
inferior nasal meatus
why does the nose run when crying
because the eye and nose are joined
what is the preganglionic parasympathetic supply to the lacrimal gland
facial nerve via nervous intermedius and travel in greater petrosal nerve then then the nerve of the pterygoid canal
what ganglion is associated with the parasympathetic supply of the lacrimal gland
pterygopalatine ganglion
what is the postganglionic parasympathetic supply of the lacrimal gland
fibres hitch hike to zygomatic branch of CNV2 to reach the lacrimal gland
what are the 6 extraocular muscles
superior oblique, inferior oblique, superior rectus, inferior rectus, medial rectus, lateral rectus
what does levator palpebrae superioris do
elevates upper eyelid and allows to open eyelid and keep open
what is the superior oblique muscle controlled by
a tendon called the trochlea which works on a pulley system
what nerve runs over the muscles in the eye
supraorbital nerve (part of ophthalmic division)
what muscle pulls the eye to the nose
medial rectus
what muscle pulls the eye to the side of the head
lateral rectus
what muscle pulls the eye upwards and medial
superior rectus
what muscle pulls the eye downwards and medial
inferior rectus
what muscle pulls the eye upwards and outwards
inferior oblique
what muscle pulls the eye downwards and outwards
superior oblique
what muscles are required to work together to look straight up or down
rectus and an oblique
what nerves innervate the motor supply of eye
oculomotor, abducens, trochlear
what muscles does the oculomotor supply
medial rectus, inferior rectus, superior rectus, inferior oblique, levator palpebrae
what muscle does the abducens nerve supply
lateral rectus
what muscle does the trochlear nerve supply
superior oblique
what does the oculomotor nerve carry parasympathetic fibres for
pupil constriction and accommodation
what does the oculomotor nerve carry sympathetic fibres for
smooth muscle of levator palpebrae superioris
what does injury to the oculomotor nerve result in
dilated pupil (mydriasis), ptosis, and eye turned down and outwards
if the pupil is dilated, what nerve has a problem
oculomotor
if the pupil is constricted, what nerve has a problem
sympathetic trunk in neck
what are the 3 layers of the eyeball
sclera, choroid, retina
what separates the posterior and anterior chamber of the eyeball
iris
how does the posterior and anterior chamber of the eyeball communicate
through the pupil
what is the eyeball made of
vitreous humour
what are the chambers of the eyeball made of
aqueous humour
what does the choroid continue as
ciliary body
what does the ciliary body form
a complete supportive ring around the lens and iris
what happens when the ciliaris muscle contracts
ring shrinks, suspensory ligaments relax and lens become rounded
what muscles does the iris contain
sphincter pupillae, dilator pupillae
where is aqueous humour secreted from
ciliary body
where is aqueous humour reabsobred
scleral venous sinus
how does glaucoma happen
from excess pressure
what helps glaucoma
drugs that constrict the pupil which can pull the venous sinus open
what happens to the lens in the absence of nerve stimulation
ciliary muscle relaxed, zonular fibres under tension, lens stretched thin to refract light for distant vision
what happens to the lens when there is parasympathetic stimulation
ciliary muscles contract, zonular fibres relax, internal tension causes lens to become more spherical to refract light for near vision
