Anatomy Flashcards
what 2 bones are most vulnerable to a blow out fracture
orbital bone of maxilla and ethmoid
what is a trapdoor fracture
orbit bone break and contents herniates and becomes trapped
what are the muscles that close the eye
obicularis Oculi (CN VII)
what are the muscles that open the eye
superior tarsal muscle (Mueller’s muscle), inferior tarsal muscles and levator palpebral superioris
what are the muscles that open the eye innervated by
CN III
what are the 3 eye layers
fibrous- sclera and cornea
uvea- ciliary body, iris, chores
retina- macula, optic disc
the lens divides the eye into segments, the segments in front of the lens is divided into _______ and ________
anterior- contains iridocorneal angle
posterior chamber- produces aqueous humor
describe the ciliary body
has suspensory ligaments (zonules) that attach to the lens. the CB itself is a sphincter muscle.
secretes aqueous humour and supports lens (for accommodation reflex)
T/F: CN VII innervates ciliary body
F: CN III
what is the path of the acqueous humour?
secreted into posterior chamber > through pupil to anterior chamber > reabsorbed via canal of schlemm at iridocorneal angle
the ______ _______ artery becomes the ______ artery. this ______ artery itself branches into _______ artery of retina and _____ artery
internal carotid artery becomes ophthalmic artery which branches into central retinal artery (end artery) and ciliary arteries
what is the fundus and what is it made up of
where light is focussed (back of retina)
- optic disc (axons meet)
- fovea (centre of macula)
- macula (greatest no of cones)
know the cranial nerves in the brain and the foramen
look at pics
what is the lacrimal apparatus made up of
lacrimal gland, secretes lacrimal fluid which washes over eye, lacrimal lake and lacirimal puncta> nasolacrimal duct
know the visual pathway
‘what starts on the outside, stays on the outside’
what innervates the lacrimal apparatus
lacrimal gland (CN V1) PS innervation of secretion of lacrimal fluid by CN VII
what are the extraocular muscles and their innervation
lateral rectus- CN VI
inferior rectus, superior rectus, medial rectus, inferior oblique- CN III
superior oblique- CN IV
what is the pulley mechanism in place for the superior oblique extraocular muscle
trochlea
where does LPS originate and insert into
origin- lesser wing
insertion- tarsus of superior eyelid
what are 3 trigeminal branches
V1- ophthalmic division
V2- maxillary division
V3- mandibular division
what is the innervation for corneal reflex (blink)
afferent: CN V1 > CN V to pons
CNS: connection between CN V and CN VII
motor: CN VII to obicularis oculi to close eye
difference between sympathetic and parasympathetic reflexes of the eye
sympathetic: more light (pupil dilation), focus on far objects
parasympathetic: less light, less focus, reflex lacrimation
what are the 6 reflexes
- wide eye opening
- pupil light reflex
- accomodation reflex
- lacrimation reflex
- vestibule-ocular reflex
- oculocardiac reflex
which muscle lack of results in Horner’s
Mueller’s muscle
T/F: sensory afferent limb for light reflex is ipsilateral and CN II innervation
T and motor limb is bilateral and CN III innervation
constriction of pupil is directed by ______ system and is when the __________ tense up
parasympathetic, sphincter pupillae fibres
dilation of pupil is directed by _______ system and is when _______ tense up
sympathetic, dilator papillae fibres
dilation of pupil is directed by _______ system and is when _______ tense up
sympathetic, dilator papillae fibres
know the pupil test and what RAPD is
RAPD= rapid afferent pupillary defect- may show pathology
what is the accommodation reflex
lens around eye changes to focus light on retina in different ways
for far vision, what does accommodation reflex do?
light doesn’t have to refract as much so…
ciliary muscle relaxed, zonules tensed, lens flattens
for close vision, what does accommodation reflex do?
light has to be refracted more with close objects and spherical objects refract more light so…
ciliary muscle contracts, zonules (ligaments relax) and lens becomes more spherical
which is parasympathetic innervation- close or far accommodation reflex
close- CN III innervated
what are the 3 types of tears
basal, reflex, emotional
reflex: afferent CN V1, efferent CN VII
what are the 4 cardinals rules for refraction of light
- close objects bend light more
- spherical objects refract light more
- ciliary muscle is sphincter
- lens wants to naturally become a sphere (PS)
what is the Monroe-Kelly Hypothesis
blood, CSF and brain volumes should all be constant. when one changes the other 2 compensate to maintain balance
what should CSF value be
NOT more than >20mmHg
how does raised ICP (through inc CSF pressure or by something in brain e.g. tumour) affect CN II?
raised ICP can transfer into subarachnoid space and compress optic nerve causing optic disc swelling
what are the 3 types of mater (mothers)
dura mater- CN V innervation
arachnoid- looks like a spider
pia mater- lines brain
subarachnoid space completely surrounds brains and spinal cord- what is in it?
circulating CSF and blood vessels
what does the dura mater create
dural septae
large septa: fall cerebri (left and right divisions) and tentorium cerebelli (superior and inferior)
small septa: sella diaphragma, falx cerebelli
what is tentorial notch and common pathology
where brain stem passes- raised ICP may compress/stretch CN III as temporal love herniates through notch
what are signs of CN III palsy
pupil dilated, down and out eye
what are sings of CN IV palsy
inward and up eye
signs of CN VI palsy
medial deviation of eye
glaucoma signs in terms of optic disc and fundoscopy
big cup due to inc loss of fibres
papilloedema signs in terms of optic disc and fundoscopy
no optic disc, haemorrhages
