ANATOMY Flashcards
which bone forms the roof (superior orbital margin) of the bony orbit
frontal bone
what is at the apex of the bony orbit
optic canal (hole)
what 2 bones form the lateral wall (lateral orbital margin) of the bony orbit (one external one internal)
zygomatic - external
sphenoid - internal
what bone forms the floor (inferior orbital margin) of the bony orbit
maxilla
what 3 bones form the medial wall (medial orbital margin) of the bony orbit
maxilla
ethmoid
lacrimal
what is the hole in the frontal bone at the top of the bony orbit
supraorbital notch
what passes through the supraorbital notch (inn the frontal bone in the bony orbit)
supraorbital neurovascular bundle
what is the hole in the front of the maxilla called
infraorbital foramen
what structure does the infraorbital neurovascular bundle go into
where does it pass through
infraorbital foramen
infraorbital canal
what is the name of the sling that holds the eye just above the floor of the orbit
suspensory ligament
if you cut the pituitary gland coronally you can see a structure beside it that curves back on itself, what is this structure
internal carotid artery
which arteries branch off the ophthalmic artery to supply the optic nerve head and external retina
ciliary arteries
which artery branches off the ophthalmic artery to supply the inner 2/3 of the retina
central retinal artery
what is the clinical significance of the central retinal artery (what type of artery is it)
what is the potential clinical presentation
it is an end artery = susceptible to ischaemia = blindness in entire eye
in the middle of which structure does the central retinal artery travel
optic nerve
what 2 things travel in the middle of the optic nerve
central retinal artery
central retinal vein
where does the central retinal vein drain into
superior ophthalmic vein
apart from the central retinal vein there are other accessory veins that drain the eye, where do they drain (2)
superior ophthalmic vein
inferior ophthalmic vein
what are the 2 options for drainage of the superior and inferior ophthalmic arteries
facial vein (anteriorly) cavernous sinus (posteriorly) - MAIN ONE
what is the danger of blood from the anterior face (eye) draining into the cavernous sinus
if infection (eg spot in the danger triangle of the face) spreads there = near the brain = meningitis, brain abscess, cavernous sinus thrombosis
another name for corneoscleral junction
limbus
what colour is the sclera
white
what happens in the sclera layer of the eye
muscle attachments
which part of the outer eye is covered in conjunctiva
sclera (also inner eyelids)
what colour is the cornea
clear/transparent
what is the angle that is ‘open’ or ‘closed’ in glaucoma called
iridocorneal angle (between the iris (flat) and the cornea (curved))
where is the cornea thickest
peripheries
which part of the eye supplies 2/3 of optical power
cornea
which part of the eye supplies 1/3 optical power
lens
what is the middle vascular layer of the eye called
uvea
which layer of the eye provides nutrition to the rest of he eye
uvea
where is aqueous humour produced
ciliary body
what shape is the ciliary body
sphincter/ring like structure
what is in front of the iris
cornea
contraction of what muscle dilates pupils
how are they arranged
dilator pupillae fibres
like sun rays around the sphincter pupillae fibres
contraction of what muscle constricts pupils
how are they arranged
sphincter pupillae fibres
like a sphincter inside the dilator pupillae fibres
what controls the sphincter pupillae muscles
parasympathetics
sphincter pupillae muscles cause pupil constriction
what controls the dilator pupillae fibres
sympathetics
dilator pupillae muscles cause pupil dilation
(think that your eyes open as wide as possible to see all danger = flight or fight response)
which edge (internal or external) of the dilator pupillae fibres is fixed
external
the internal is attached to the sphincter pupillae to move it (pupil vasodilation)
where is the anterior eye segment in front of
the lens
where is the posterior eye segment behind
the lens
where are the photoreceptors in the eye in comparison to veins, arteries, ganglion etc
posterior
not a typo, the light has to go through all the other layers before it reaches them
what are the 2 cell types that after the light signal before its passed on to ganglion cells
horizontal cells
amacrine cells
what are the 2 types of photoreceptor
rods
cones
where are there rods
peripheries of eye
where are there cones in high density
fovea
which photoreceptor has low visual acuity but supplies your peripheral vision
rods
which photoreceptor has detailed, colour vision
cones
what happens to light signals after they’ve been passed from the photoreceptors to ganglion cells
axons of optic nerve
where are the ganglion cells in respect to the photoreceptors
anterior
why do we have a ‘blind spot’
there are no photoreceptors in the optic disc (need space for blood vessels nerve fibres etc)
what is the fovea
middle 1.5mm of macula
what does the macula look like on fundoscopy
darker red circle horizontally in line with the optic disc
on fundoscopy where do the central retinal artery and vein enter
optic disc
what are the red lines you can sometimes see on the white bit of your eye
dilated conjunctival vessels
sclera is covered in conjunctiva that is vascular
what is the name of the conjunctiva on the inner eyelids
palpebral conjunctiva
what is the name of the conjunctiva on the sclera
bulbar conjunctiva
what is the angle between bulbar conjunctiva (on sclera) and palpebral conjunctiva (on inner eyelid) called
conjunctival fornix
how is the lens connected to the ciliary body
suspensory ligaments of the lens
what shape is the ciliary body
sphincter/ring like shape
for far vision what happens to the lens
how does the ciliary body achieve this
flattens
ciliary body relaxes
for close vision what happens to the lens
how does the ciliary body achieve this
becomes more spherical
ciliary body contracts
if there is parasympathetic supply to the ciliary body what happens to it
what happens to the lens
what type of vision is this used for
contraction of ciliary body
more spherical lens
close vision
what are the 2 chambers of the anterior eye segment (in front of lens)
anterior chamber
posterior chamber
where is the anterior eye chamber
between iris and cornea
in anterior segment
where is the posterior eye chamber
between iris and suspensory ligaments
in anterior segment
2 main components of aqueous humour
ascorbate (antioxidant)
bicarb (made from carbonic anhydrase)
if you want to decrease aqueous humour production (to decrease intraocular pressure) what do you give
carbonic anhydrase inhibitor
normal intraocular pressure
17mmHg
where is aqueous humour produced
ciliary body
from production of aqueous humour in ciliary body, where does it go next
posterior chamber of anterior segment
what does aqueous humour do in the posterior chamber of the anterior segment of the eye
nourish lens
what does aqueous humour do in the anterior chamber of the anterior segment of the eye
nourish cornea
where does aqueous humour drain after its nourished the cornea in the anterior chamber (specifically)
where is in relation to the iris and cornea
scleral venous sinus and trabecular meshwork
between the iris and cornea (iridocorneal angle)
where do ‘floaters’ arise
posterior segment of eye, vitreous body
which segment of the eye is associated with aqueous humour
anterior
which segment of the eye is associated with vitreous humour
posterior
what is the orbicularis oculi supplied by
why
CN VII facial nerve
muscle of facial expression (closing eyes)
what is the orbicularis oculi used for
closing eye
what are the 2 parts of the orbicularis oculi
palpebral part
orbital part
what is the palpebral part of the orbicularis oculi used for
blinking
what is the orbital part of the orbicularis oculi used for
screwing up your eyes
which part of the orbicularis oculi is the outside bit
orbital part
Orbital = Outside of Orbicularis Oculi
what 2 things lift the superior tarsus muscle
mullers muscle
tendon of levator palpebral superioris
nerve supply of tendon of levator palpebrae superioris (the one that lifts the superior tarsus)
CN III
bc its closer to the eye than orbicularis oculi (its supplied by CN VII)
nerve supply of lacrimal gland
CN VII
what does the lacrimal gland produce
lacrimal fluid (tears)
what 3 things are in basal tears (to nourish the avascular cornea)
lysozyme
IgA
IgG
where is the lacrimal gland
above the eye laterally
what is the swelling in your lower eyelid called
lacrimal papilla
what is the hole in the swelling in your lower eyelid called
lacrimal puncta
how do tears get from the lacrimal gland to the lacrimal canaliculi (medial aspect of eye)
washed over with a blink
where does lacrimal fluid drain after it enters the lacrimal puncta (small hole in bottom eyelid)
then the …
lacrimal sac
nasolacrimal duct
where does the nasolacrimal duct drain into
inferior meatus of nasal cavity (below the inferior concha)
what component of tears has an antibiotic property
lysozyme
for the superior and inferior obliques to work, which other extraocular muscles needs to be in use
(just think about it from a superior view)
medial rectus
when the eye is medially rotated you will use your superior and inferior obliques to look up/down
what does your medial rectus do
adduct (medially rotate)
what does your lateral rectus do
abduct (laterally rotate)
what does your superior rectus do
lift eye superiorly when in an abducted (lateral) position
what does your inferior rectus do
make eye look down when in an abducted (lateral) position
what does you inferior oblique do
lifts eye superiorly when in an adducted (medial) position
what does your superior oblique do
makes eye look down when in an adducted (medial) position
for the superior and inferior rectus muscles to work which other extraocular muscle must be in use
(just think about it from a superior view)
lateral rectus
when the eye is laterally rotated it lines up with the superior and inferior rectus muscles (bc they travel medially back towards the tendon sheath which is beside the optic canal
what 2 extraocular muscles work together when you want to look STRAIGHT UP
superior rectus and inferior oblique
what 2 extraocular muscles work together when you want to look STRAIGHT DOWN
inferior rectus and superior oblique
what is the optic nerve surrounded by (2)
what clinical condition is this important in
meninges (dura mater, pia mater, arachnoid)
cerebrospinal fluid
papilloedema (compression of optic nerve from increased intracranial pressure)
where should your blind spot be (in the test you start in the middle and work temporally)
15 degrees temporal
what are the 2 branches of CN III
superior and inferior
what 2 extraocular muscles does the superior branch of CN III supply
superior rectus, levator palpebrae superioris (LPS)
the 2 superior muscles
what does the inferior branch of CN III supply (3)
medial rectus
inferior rectus
inferior oblique
(the 3 non superior ones)
what does the superior branch of CN III supply parasympathetics to
ciliary body
sphincter pupillae
(the 2 sphincters)
where does CN II enter the skull
optic canal
where does CN III enter the skull
superior orbital fissure (same as CN IV, V1, VI)
what does CN IV supply
superior oblique
bc its the trochlear nerve = supplies the extraocular muscle that goes through the trochlea
what does CN VI supply
lateral rectus
bc its the abducent nerve = supplies the extraocular muscle that causes eye abduction
what is the pneumonic thing for remembering the CN supply of extraocular muscles
LR6 SO4 AO3
which CN that supplies something in the eye has a weird course;
arises from the back (dorsum) of the brainstem (rest are anterior) and crosses over (so the one that started off at the left ends up at the right eye)
CN VI abducent
where does CN VI enter the skull
superior orbital fissure
same as CN III, IV, V1
what is the general function of CN V
facial sensation
what are the 3 branches of CN V
ophthalmic V1
maxillary V2
mandibular V3
what is the name of CN VII
facial nerve
which CN V is the supraorbital nerve a branch of
CN V1
which CN V is the infraorbital nerve a branch of
CN V2
which CN V has a nasociliary branch
CN V1
where does the nasociliary branch of CN V1 supply (2)
cornea
tip of nose
which facial nerve branch can be affected in shingles
CN V1 nasociliary branch
which nerve supplies sensory to upper eyelid (be specific)
CN V1
which nerve supplies sensory to lower eyelid (be specific)
CN V2
CN VI palsy, when is there diplopia
when looking laterally
common aetiology of optic chiasm compression
pituitary tumours
how does pituitary tumour compressing on optic chiasm present with patients eyesight
bitemporal hemianopia (loss of peripheral vision, bc nasal retina AP transmission is disrupted)
where do the sympathetic nerves to the eyes go after they synapse (what do they follow)
hitch a ride on internal carotid then ophthalmic artery (part of periarterial plexus)
pre synaptic sympathetic chemical
ACh
post synaptic sympathetic chemical (stimulates eyes)
noradrenaline
sympathetic affect on pupils
via
dilation via dilator pupillae fibre contraction
example of sympathetic control of pupils in normal physiology (1)
dim lighting
pupil dilation
example of sympathetic control of pupils iatrogenic (1)
mydriatic drugs (pupil dilators)
pupil dilation
post synaptic parasympathetic chemical (stimulates eyes)
ACh
pre synaptic parasympathetic chemical
ACh
where are the parasympathetic ganglions for the eye
right next to the eye
parasympathetic affect on pupils
via
constriction via pupillae sphincter contraction
example of parasympathetic control of pupils in normal physiology (1)
bright lights
example of parasympathetic control of pupils pathologically
horners syndrome
fixed pin point pupil cause
opiate drugs
what should happen if you shine a torch into 1 eye
both eyes constrict
what is the afferent limb (from eye to brain) in the pupillary light reflex
CN II (optic nerve, bc photoreceptors recognise the light)
what is the efferent limb (from brain to eye) in the pupillary light reflex
CN III (oculomotor bc it supplies the pupillae sphincter/dilator fibres)
what are the 4 steps of the pupillary reflex (when you shine a torch in one eye)
- from eye to midbrain
- edinger westphal (EW) nucleus in midbrain
- ciliary ganglion
- short ciliary nerves to sphincter pupillae muscles
in the pupillary light reflex, if there is no constriction contralateral side what nerve damage is there
CN III (efferent nerve for pupillary reflex)
in the pupillary light reflex, if there is no constriction in either eye what nerve damage is there
CN II (afferent nerve for pupillary reflex)
what happens to accommodation reflex as you get older
it decreases
which nerve are you testing with the accommodation reflex
CN III
how do you test accommodation reflex clinically
make someone go ‘cock eyed’ by following the pen torch as you bring it in towards their nose
what are the 3 things that should happen bilaterally in accommodation reflex
convergence ('cock eyed')
pupil constriction
spherical lens (ciliary body contraction)does the long ciliary nerve enter the ciliary ganglion
no
goes above it
does the short ciliary nerve enter the ciliary ganglion
yes
what is the ciliary ganglion
a place nerves go through/synapse at near the eye
efferent limb of blink reflex (from brain to eyelid - palpebral orbicularis oculi)
CN VII (bc its a facial thing not an eye thing)
afferent limb of blink reflex
CN V1 (bc this is the sensory supply to the upper face incl upper eyelid)
which nerve supplies the lacrimal gland (motor)
CN VII
afferent limb of tear reflex (from eyes to brain eg if its windy)
CN V1
efferent limb of tear reflex (from brain to eye)
CN VII
