Orbit, Eye, & Vision Part 1 - Herring Flashcards
a thickened funnel-shaped fascial layer
periorbita
Lateral walls are at a _____° angle which places the axis of orbit at about ___° (to each other)
90 ; 45
Optical axis of eyeball is ______ when looking straight ahead (primary position; eye at rest)
parallel
_____ and _____ walls of the orbit are thinnest
Medial ; inferior
a condition where the eyeball or eyeballs bulge out of the eye socket
Exophthalmos (proptosis)
space between upper & lower eyelids
Palpebral fissure
Medial & lateral palpebral
commissures (also known as
canthi) at the ______ of the
eye
corners
What glands help to keep the eyelids from sticking to each other and prevent evaporation of tears
Ciliary glands (which are sebaceous glands)
Between eyeball & inner aspect of eyelids (closed sac when the eyelids are brought together)
Conjunctival Sac
What muscle acts as the sphincter of the eyelids (brings eyelids together)
Orbicularis oculi
What glands:
Prevent tears from evaporating
Increases surface tension of tears
Tarsal glands
Separates superficial fascia of the face from the orbital contents, essentially what acts as a boundary so something like a contact couldn’t go back behind/under the eye
Orbital septum
Superior eyelid: Two muscles elevate (open) the upper lid
Levator palpebrae superioris
Superior tarsal (Mueller’s) muscle
Levator palpebrae superiori is what kind of muscle
skeletal
Levator palpebrae superiori is __________ innervated because it is skeletal muscle
Somatically
Superior tarsal (Mueller’s) muscle is ______________ innervated
Sympathetically
What muscle is responsible for “tone” of the eyelid
Superior tarsal (Mueller’s) muscle
Lesion to the nerve pathway to either Levator palpebrae superioris or Superior tarsal (Mueller’s) muscle results in
partial ptosis (drooping) of the upper eyelid
Forms when a ciliary gland of the eyelid is blocked
Typically on the edge of the eyelid near the base of an eyelash
Painful
Stye
Forms when a tarsal gland is blocked
Usually deeper in the eyelid –
typically forms on the inner aspect of the upper eyelid
Generally aren’t painful
Chalazion
The lacrimal gland produces lacrimal fluid (tears)
which is crucial for corneal health, why is this so?
The cornea does not have it’s own blood supply so it relies on the lacrimal fluid
Cleanses
Collects irritants
Drains to medial angle of the
eye
Lacrimal fluid of the lacrimal gland
Excretory ducts open into the
superior conjunctival fornix
lacrimal gland fluid flows from ______ to ______ within the conjunctival sac by gravity and when we blink
lateral ; medial
2 small openings near medial angle of the eye drains fluid from surface of the eyeball
Lacrimal puncta
Gets the fluid from the lacrimal puncta and drains it into the lacrimal sac
Lacrimal canalicul
Drains fluid from the lacrimal canaliculi to the inferior nasal meatus (inferior to the inferior nasal concha) where it is then drained posteriorly & swallowed
Nasolacrimal duct
The eyeball is composed of three layers, what are they
fibrous (outer) layer
vascular (middle) layer
inner layer
What consists of the fibrous (outer) layer
Sclera
Cornea
What consists of the vascular (middle) layer
choroid
ciliary body
iris
What consists of the inner layer
Retina
The eyeball is also composed of 3 chambers:
Anterior chamber
Posterior chamber
Vitreous chamber
What chamber is between cornea & iris
Anterior chamber
what chambers are filled with aqueous humor
Anterior and Posterior chambers
What (small) chamber is between the iris and lens
posterior chamber
What (large) chamber is between the lens and retina
vitreous chamber
what chamber is filled with vitreous body (a gelatinous mass)
vitreous chamber
The eyeball has 4 structures involved in the refraction of light
- Cornea
- Aqueous humor
- Lens
- Vitreous body
Which structure of the eye is involved in fixed refractive power
cornea
Which structure of the eye is involved in adjustable refractive power
lens
What of the fibrous (outer) layer consists of
Opaque
Posterior 5/6th
Muscle attachment
VASCULARIZED (bloodshot eyes)
Sclera
What of the fibrous (outer) layer consists of is
Transparent
Anterior 1/6th
AVASCULAR
Maintained by aqueous humor (posterior surface) & lacrimal fluid (anterior surface)
Cornea
The cornea is highly sensitive and is innervated by what branch of CN V
CN V1
What part of the VERY VASCULARIZED (middle) Layer
Lines most of sclera
Adherent to retina
Terminates at ciliary body
Supplied by branches of ophthalmic a.
Choroid
What part of the Vascular (middle) Layer
Connects choroid to iris
Posterior to corneoscleral junction
Ciliary Body
The Ciliary muscle / Ciliaris muscle = smooth fiber is ____________ innervated
parasympathetically
Radial fibers make up the ciliary muscle in the vascular (middle) layer which help _______ to change thickness of lens
contract
Ciliary processes are covered by ciliary epithelium that produces
aqueous humor
Ciliary processes are covered by ciliary epithelium that anchors ________ that attach to the lens
zonular fibers
What in the vascular layer has smooth muscle fibers which control the size of the pupil (contractile diaphragm)
Iris
2 smooth (involuntary) muscles in the iris control size of the pupil, what are they
Sphincter pupillae
Dilator pupillae
Sphincter pupillae - Circular fibers that are __________
innervated
Which CN
parasympathetically
CN III
** makes pupil smaller **
Dilator pupillae - Radial fibers that are _______ innervated
sympathetically
** makes pupil bigger **
Light hits which layer first in the retina
Inner first then outer
Two important layers of the retina, what are they
Photoreceptive layer
Ganglion cell layer
What layer of the retina is the outer layer and is made up of rods & cones
photoreceptive layer
what layer of the retina is the inner layer and has 1st order cell bodies for vision that travel to the optic disc & then exit to form CN II
Ganglion cell layer
Phototransduction occurs at the ______ layer (rods & cones)
photoreceptive
Light energy is converted to __________
electrical potentials
Membrane potentials then travel from outer layer (rods & cones) to ______ layer
(ganglion cells)
inner
Ganglion cell axons of the eyeball then travel to exit the eyeball at the _______ & then form the ________
This is where our __________ neurons for vision are located
optic disc
optic nerve (CN II)
1st order
Concentrated in the central retina
Color vision
High visual acuity
Photopic vision
In well-lit settings
Require more light to function
Cones
Concentrated in Peripheral retina
Mostly gray tones
Less visual acuity
Scotopic vision
In low-light settings (night vision)
Very sensitive to light / require less light
Rods
Site where axons of the ganglion cells converge & leave the eyeball to form CN II
** in the inner layer of the retina **
Optic Disc (in the inner layer of the retina)
Central a/v of the retina enter/exit here
Optic Disc
What contains fibers only and no photoreceptor cells (“blind spot”)
Optic Disc
What is
Lateral to optic disc
Central (detailed) field of vision
Macula lutea (in retina)
Area of highest visual
acuity
Located in visual
axis (0°)
Only cones (no rods)
Fovea Centralis
Clear watery fluid in the anterior and posterior chambers of the eyeball is _____ and where is it in the eye?
Aqueous Humor - Cornea
Provides nutrients and removes metabolites from cornea and lens
Aqueous Humor - Cornea
Produced continually by the ciliary processes and passes from the posterior chamber into the anterior chamber via the pupil
Aqueous Humor - Cornea
Aqueous Humor - Cornea is drained away through spaces at the _________ (filtration angle)
iridio-corneal angle
The iridio-corneal angle drain into the
scleral venous sinus (canal of Schlemm)
Blockage of the venous canal can be one cause of
glaucoma
Transparent biconvex structure held within a transparent capsule
Lens
Surrounded by the ciliary processes from which the highly elastic, radially-arranged suspensory ligaments of the lens (zonular fibers) arise
Lens
Fills the eyeball posterior to the lens (vitreous chamber
Vitreous body
Holds retina in place & supports the lens
Jelly-like matrix (gelatinous mass) with a fine meshwork of collagen fibers
Vitreous body
Not continually replaced (present at birth) and that’s what you have for life
Vitreous body
Leading cause of blindness in the world
Cataracts
2nd leading cause of blindness in the world
Glaucoma
Glaucoma = ______-angle (typically gradual onset)
Open
Glaucoma = ______-angle (typically sudden onset)
closed
Due to increased volume:
Increased secretion / production AND/OR
Obstructed drainage of aqueous humor
Glaucoma
Branch of ICA
Principal blood supply to orbit
Travels superior to optic nerve (CN II)
Travels through medial aspect of orbit
Ophthalmic Artery
The ophthalmic artery gives rise to this artery that pierces CN II and is the primary blood supply of the inner retina, what is it?
Central artery of the retina
What artery pierces CN II and is the primary blood supply to the inner retina
central artery of the retina
Superior & inferior ophthalmic veins communicate with:
angular vein ________
cavernous sinus _________
pterygoid venous plexus _______
anteriorly ; posteriorly ; inferiorly
Superior ophthalmic vein travels from the superomedial aspect of the orbit anteriorly to the superolateral aspect posteriorly to exit through the _____
superior orbital fissure
CN V1 is purely
sensory
CN V1 divides into what 3 nerves
** NFL from M –> L **
nasociliary
frontal
lacrimal
What nerve suspends ciliary ganglion
nasociliary nerve
What ganglion is associated with short ciliary nerves but not with long ciliary nerves
Ciliary Ganglion
What nerve is:
Sensory fibers from eyeball to nasociliary nerve
Pass through the ciliary ganglion
Fibers hitching a ride:
- PostGPS
- PostGS
Short ciliary nerves
What nerve is:
Sensory fibers from eyeball to nasociliary nerve
Do not go through ciliary ganglion
Fibers hitching a ride:
- PostGS
Long ciliary nerves
The Anterior & Posterior Ethmoidal nerves are __________ branches carrying information from sphenoidal & ethmoidal sinuses and anterosuperior nasal cavity
sensory
Corneal Reflex - Sensory Limb
Short and long ciliary nerves to CN _____
V1
Corneal Reflex - Sensory Limb
** mostly conveys pain and temperature **
Where are the 1st order cell bodies? and these axons travel in the spinal trigeminal tract
Trigeminal ganglion
Corneal Reflex - Sensory Limb
Where are the 2nd order cell bodies? and the axons project ________ to facial motor nucleus and superior salivary nucleus aka the ______ limb
Spinal trigeminal nucleus bilaterally
motor
Corneal Reflex - Motor Limb = __________ nucleus sends axons ipsilaterally as part of CN VII to orbicularis oculi to do what ?
facial motor ; blink
Corneal Reflex - Motor Limb =
For the tearing component of the corneal reflex (lacrimal reflex), axons from 2nd order neurons project to the ______________ nucleus (preGPS cell bodies) which projects to the __________
superior salivatory nucleus ; lacrimal gland
What nerve:
sensory information from forehead
has the supratrochlear and supraorbital nerves as its terminal branches
Frontal nerve
What nerve:
Has sensory ONLY innervation from skin near lacrimal gland
If this nerve is damaged, there is no disruption to the lacrimal gland
Lacrimal Nerve
PreGPS cell bodies of the lacrimal gland are in the
superior salivary nucleus
PreGPS fibers of the lacrimal gland travel out of CN _____ and then branch off of it as _________ nerve
CN VII and greater petrosal
PostGPS cell bodies of the lacrimal gland are in the
pterygopalatine ganglion
PostGPS fibers of the lacrimal gland travel on the distal portion of CN ____ to get to the lacrimal gland
V1
Parasympathetic Eyeball muscles are involved in ________ innervation of the pupil and ____ accommodation (changes shape of the lens for near vision)
parasympathetic ; lens
** protects pupil **
Sympathetic eyeball muscles are involved in _______ of the pupil and has _____ role in lens accommodation
dilation ; no
PS pathway of the eyeball =
PreGPS cell bodies are in the
Edinger-Westphal nucleus
PS pathway of the eyeball =
PreGPS fibers exit as CN
III
PS pathway of the eyeball =
PostGPS cell bodies are in and synapse on the _______ ganglion
ciliary
PS pathway of the eyeball =
PostGPS fibers travel on _____ ciliary nerves of CN ________
short ; V1
PS pathway of the eyeball targets
constrictor (sphincter) pupillae & ciliary muscle
** this is what changes tension on the zonular fibers which changes the shape of the lens for lens accommodation **
S pathway of the eyeball =
PreGS Cell bodies are in
IML T1
S pathway of the eyeball =
PreGS fibers ascend in the ____________ to the ___________ ganglion
sympathetic trunk ; superior cervical
S pathway of the eyeball =
PostGS cell bodies are in and synapse on the __________ ganglion
spuperior cervical
S pathway of the eyeball =
PostGS fibers are in the _____________ to the internal carotid artery plexus to ophthalmic artery plexus to ______ and ______ ciliary nerves
cephalic artery ramus ; short ; long
S pathway of the eyeball target
dilator pupillae muscle
What muscle of the eyeball muscle is involved in
Sympathetic control
Radial arrangement of smooth muscle dilates pupil
* Low light
Dilaor pupillae
What muscle of the eyeball muscle is involved in
Parasympathetic control
Circular arrangement of smooth muscle constricts pupil
* Bright light
Sphincter (constrictor) pupillae
What muscle acts like a sphincter and suspends lens by zonular fibers
ciliary muscle
Lack of nerve stimulation aka no parasympathetic stimulation
Tension on zonular fibers pulls on lens
Lens stretches (becomes thinner) = distance vision
Means the ciliary muscle is ______ and has what kind of diameter
relaxed ; large
Parasympathetic stimulation
Decreased tension on zonular fibers
Lens becomes more spherical = near vision
Means the ciliary muscle is ______ and has what kind of diameter
Contracted ; small
What part of the conjunctiva is inside the eyelid
Palpebral
What part of the conjunctiva is reflects on the eyeballs
Bulbar
Ganglion cells cannot convert to _____ directly
LIGHT
What 2 targets would the postGPS fibers hitching a ride on the short ciliary nerves have
sphincter pupillae
ciliary muscle
What target would the postGS fibers hitching a ride on the short ciliary nerves have
dilator pupillae
What would we see if we damage V1 to the right eye and we touch it?
No blinking in either eye because no perception of something touching the right eye
What would we see if we damage right V1 and touch the left eye?
blinking in both eyes
What if we damage CN VII on the right side and touch the right eye? what about the left eye?
Same answer for both
Nothing in the right eye but the left eye would blink and have tear production
PostGPS fibers hitch a ride on the very ______ aspect of V1
distal
Because postGPS fibers hitch a ride on the very distal aspect of V1, if we cut the lacrimal nerve or damage it close to the lacrimal fossa of the frontal bone or close to the lacrimal gland itself, we lose ?
Sensory to the upper lateral part of the eye/orbit AND innervation to the lacrimal gland
Because postGPS fibers hitch a ride on the very distal aspect of V1, if damage the lacrimal nerve as it’s branching off V1 near the apex of the orbit or V1 itself, we lose?
only sensory loss to the superolateral skin of orbit
** nothing happens to the lacrimal gland **
if you damage short ciliary nerves of the eyeball, what 3 things do we lose? clarify if partial or complete
partial sensory loss (because we have the long ciliary nerves)
partial sympathetic loss (because we have the long ciliary nerves)
complete loss of the parasympathetic pathway
Damaging the short ciliary nerves of the eyeball results in complete loss of the parasympathetic eyeball, what symptoms do we see?
dilated pupil and issues with lens accommodation
