Optic Flashcards
What bones make up the outer rim of the orbit?
frontal- superior roof
zygomatic- lateral
maxilla- medial and inferior/ largest part of floor
What makes up the inside of the orbit?
lacrimal
ethmoid
sphenoid
palatine
What are the base and apex of the orbit?
base- orbital margin
apex- optic canal
What happens if you get directly hit in the eye?
“blown out fracture”
maxillary sinus/floor can fall in
eye fall in
How do we keep our eyes straight ahead?
eyeball/ axis of orbit angled
What is the space between the upper and lower lids?
palpebral fissue
palpebral margins meet at canthi (angle)
eyes want to close at rest
What opens the eye lid?
aponeurosis of levator palpebrae superioris
no muscle for lower lid
What helps close lid>
orbicularis oculi
straight when contracted
What opens the eyes wide during flight or fight?
tarsal gland
sympathetic response
What are the 7 layers of the eyelid?
external to internal
skin subcutaneous connective tissue (fat) muscular layer submuscular layer tarsal plate tarsal glands palpebral conjuctiva
What protects and lubricates the eye?
superior and inferior palpebrae
What are involved in the eyelid?
musculocutaneous junction- where skin hits palpebral conjuctiva
palpebral conjuctiva- mucus memvrane on inside of eyelid
orbital conjuctiva- becomes continous with PC/ protective covering of eye
What causes Horner’s syndrome?
lesion to the superior cervical sympathetic ganglion
results in paraslysis of tarsal muscle on affected side
ptosis (drooping eye lid)
myosis (small pupil)
anhydrosis (lack of sweating and reddness of skin on affected side)
What are the edge corners of the eye?
medial and lateral canthus
What is the larger medial angle of the eye?
lacrimal lake
What fleshy elevation seen in the medial angle of the eye within the lacrimal lake tht contains sweat glands, sevbaceous glands, and cilia>
lacrimal caruncle
yellow and white secretion found when you wake up in the morning
What is the connective tissue that separates the sclera from the lacrimal lake found lateral to the lacrimal caruncle?
plica semilunaris
What is the third eyelid in other animals>
plica semilunaris
What is thee lacrimal punctum?
drain for the eye
Where does the lacrimal gland ducts drain>
superior palpebral fornix
What does the lacrimal gland secrete?
solution with baceriocidal enzyme lysozyme
provides nutrients and dissolved oxygen to cornea
Where do tears go?
collect in superior fornix of upper lid
pass over the eye surface
aided by blinking
How do tears drain?
puncta lacrimali- drain opening
lacrimal canaliculus- duct
lacrimal sac- collection fluid
nasolacrimal duct- drain to nasal sinus
What kind of nerves innervate the lacrimal gland?
parasympathetic CN VII
greater petrosal nerve branch
How is the lacrimal gland innervated?
greater petrosal nerve joins deep petrosal nerve (sympathetic) and forms nerve of pterygoid canal
runs through pterygoid canal
goes to pterygopalatine fossa to pterygopalatine ganglion
Which fibers synapse at the pterygopalatine ganglion?
parasympathetic fibers ONLY
What happens after parasympathetic fibers synapse?
rejoin with sympathetic fibers to join with maxillary nerve V3 and follow zygomaticotemporal branch anteriorly
join lacrimal branch of V2 to lacrimal gland
How do parasympathetic and sympathetic stimulation affect lacrimal secretion?
parasym- increase secretion/tearing
symp- vasoconstrution and decrease in tear production
What are the muslces of the orbit called?
extraocular muscles (6)
What are the recti muslces of the eye?
superior rectus
inferior rectus
medial rectus
lateral rectus
all originate from anulus tendineus ring around orbital fissure and optic canal
What orbit muscles do not orignate from anulus tendineus?
superior oblique
inferoir oblique
levator plapebrae superioris
What does superior oblique attach to?
facial sling = trochlea
Why is there a medial pull of superior and inferior rectus?
orbit directed in medial to lateral direction
How does the CNS reposition the eye?
The 6 extraocular muscles function at all times
changing tension moves quickly
How do the oblique muscles pull?
IO-UO, SO-DO
inf obl up and out
sup olb down and out
What are the two divisions of the CN III?
superior and inferior
What does the superior diviion of CNIII innervate?
levator palpebrae superior and supieror rectus
What does the inferior division of CNIII innervate?
medial and inferior rectus and inferior obique
carries parasympathetic fibers to ciliary ganglion
What does the trochear near CN IV inneravte?
superior oblique (pass through trochlea)
What does the abducent nerve CN VI innervate?
lateral rectus (abducts eye)
only CN from dorsal brain
How do CN II, CN IV, CN VI enter the orbit?
superior orbital fissure
LR6 SO4 AO3
What is the largest nerve in the orbit?
optic nerve CN II
enters through optic canal with ophthalimic artery
covered by mengines /dura
What is the largest nerve in the orbit?
optic nerve CN II
enters through optic canal with ophthalimic artery
covered by mengines /dura
What does ophthalmic nerve CN V1 suplly?
sensory innervation to orbit and external eye
enters through superior orbital fissure
What are the 3 branches of the CN V1?
lacrimal nerve
frtonal nerve
nasocilliary nerve
Where is the lacrimal nerve?
lacrimal nerve in lateral goes to lacrimal gland
sensory innervation to lacrimal gland and lateral aspect of the eye and upper and lower palpebrae
What are the two branches of the frontal nerve?
supratrochlear nerve- supplies sensory innervation tothe skin above the medial canthus and part of scalp
supraorbital nerve- more lateral- supplies superior palpebra and scalp. exits orbital via supraorbital foramen
What does nasociliary nerve cross?
on top of optic nerve from lateral to medial
What are the branches of the nasocilliary nerve?
communicating branch to ciliary ganglion long ciliary nerves posterior ethmoidal nerve antior ethmoidal nerve infratrochlear nerve
Wht is a short cilliary nerve?
anything coming out of ganglia to back of eye
What is a long ciliary nerve?
anything that goes stright to the back of the eye
provides sensory innervation to eye (cornea sclera ciliary)
What is the communicating branch to the ciliary ganglion?
runs trhough ciliary ganglion WITHOUT synapsing to reach eye by short ciliary n
What does posterior ethmoidal nerve do?
posterior and middle ethmoidal air cells on medial wall of orbit
What is anterior ethmoidal nerve?
middle and anterior ethmoidal air cells
complex course to end as external nasal nerve for external nose
What is the terminal branch of the nasociliary nerve?
infratrochlear nerve
supplies medial canthus lower eyelid and nearby region of orbit
Wht is a short cilliary nerve?
anything coming out of ganglia to back of eye
paraympathetic, sympathetic, and sensory
What is the terminal branch of the nasociliary nerve?
infratrochlear nerve
supplies medial canthus lower eyelid and nearby region of orbit
What happens at the ciliary ganglion?
locted between optic nerve and lateral rectus
semsory and sympathetic fivers run through WITHOUT synapsing in it
Parasympathetic fibers from CN III DO synapse
what do sympatehtic fibers do in the eye?
come from superior cerival ganglion for CN V1
dilator puplillae to dilate pupil
can reach short or long ciliar
What do parasympathetic fibers do in the eye?
originate from edinger westphal nuclear for CN III
constrict pupil (sphincter puillae) to focus on near objects (contract ciliary muscle)
What are the nerves of the orbit?
optic nerve II oculomotor III trochlear IV Trigeminal V1 abducent VI sympathetics parasympathetics
What is the most medial part of the orbit ALWAYS?
superior oblique
How does the ophthalmic artery enter the oribit?
optic canal
What does the ophthalmic artery supply?
blood to the orbit including eye itself
What are the branches of the ophthalmic artery?
mengineal branches lacrimal (lateral) central retinal long and short ciliary (choroidal) supraorbial anterior ethmoidal posterior ethomoidal supratrochlear medial and lateral palebral dorsal nasal
What happens if there is a plaque on the central retinal artery?
blood to rods and cones inhibited
BLIND
pierces dura to optic disc
What is the venous drainage of the orbit?
suprioer and inferior ophtalmic veins
exit through superior orbital fissure
enter cavernous sinus
what do anterior and poseterior cillary arteries supply?
anterior- blood supply to front of eye
posterior– blood supply to back of eye
what do anterior and posterior cillary arteries supply?
anterior- blood supply to front of eye
posterior– blood supply to back of eye
What are the 3 chambers of the eye?
anterior chamber- between cornea and iris filled with aqueous humor
posterior chamber- between iris and lens filled with aqueous humor
postremal viterous chamber- behind the lens willed with gelatinous viterous humor
what are the 3 layers of the eye?
sclera- posterior 5/6ths of eye. opaque. becomes continous with the dura
choroid- intermediate layer
retina-
What is the cornea?
transparant principal refracting medium of the eye that roughly focuses image onto retina
main focus, espeically after 10 feet
5 layers
AVASCULAR- gets diffusion of metaboites from aqueous humor and blood vells of limbus, and some o2 from environment
why do you get red eye in photos?
eye is very vascular- light emphasises the blood vessels
uveal layer- middle layer
What is the ciliary body?
in uveal ayer with
continous with choroid
bulk consists of smooth muscle (ciliary muscle) around the lens that contracts to reduce tension of the suspensory ligament to thicken lens
far vision- lens open
near visiton lens smaller (ciliary contracts)
parasymptaheic nerve fibers CNIII via ciliary ganglion
What do ciliary processes do>
folds in ciliary body that continously produce aqueous humor
AH is like CSF
provides metabolites to cells and reabsobd into canal of Schlemm
fluid pumped and pulled into drain- if build up willl compress retina = glaucoma
What is the number 1 cause of blindness?
glaucoma- increased intraocular pressure
compresses retina, optic nerve and blood vessels= not draining aqueous humor
blurred vision, halos around bright objects, pain, blindness
What is the difference between open angle glaucoma and angle closure glaucoma?
Open-
closed- blocked trabecular netwowrk and too much AH produced trapped in posterior chamber iris lifts off lens
What is the lens?
arise from ciliary body
anteior art of uveal layer of eye
shutter on camera
finetuning close vision
nuclei may be missing or on the side to not block view
What muscles control the pupil?
constrictor pupillae- circumferentially oriented smooth muscle PARASYMP
dialate- radially oriented dilator pupillae muscle. SYMP
constant regulation
What does limited light do?
helps retina
smaller hole- better focus
How is the cillary muscle innervated?
paraympathetic only! causes lens to thicken
circumferential
What is considered far vision>
after 10 feet
what happens when changing vision from far to near?
parasympathetic system
lens fatter/pupil constrict
What are the layers of the retina?
outter- rods and cones w/ cell bodies= photoreceptors
middle- bipolar cells (integrate sensory input from receptor before CNS)
inner- ganglia of optic nerve
What are rods vs cones?
rods not for day light for dim 1 type of photopigment edgoes but not color long/easy to hit = single photos
cones
daylight
faster on/off
color- relative to output %
What is the first optic action potential>
optic nerve
How does like travel through retina?
light goes through cell layer to photoreceptors
neural info goes opposite direction
What is the weakest part of the rena? dark spots/blurry
where photoreceptors meet the layer can lift off if not fixed they die
What is the pigmented epithelia>
back stop so light only goes through eye once- otherwise “house of mirrors”
what is a mueller cell?
retinal barrier and support
What is the fovea?
cones only, no rods
direct stimulation from light
weakest blood supply
What is the blind spot of the eye?
retina on lamina ribrosa = optic papilla (optic disc)
optic disc= where blood vessels come in (retinal artery)
no photoreceptors
apex points medially
different between each eye
What artery supplies blood to the eye?
ophthalmic
retinal and uveal systems
central artery of retina and central vein of retina
uveal= ophtahlmic artery branches of ciliary arteries long and short
What is venus drainage of the retina?
central vein
drains to cavernous sinus (may join ophtalmic veins)
What happens if there is a change in CSF?
will squeeze into optic nerve
artery and nerve okay but vein can collapse
papilladeema = blood build up and disc bulge
What is the most superfical nerve in the orbit?
Frontal
What is macular degeneration>
deteriation of central portion of retina
can lead to blindness
