7 - Eye and Orbit Flashcards
Palpebral conjuctiva –
membrane lining inner eyelid
Bulbar conjuctiva –
membrane lining surface of eye
Conjuctival sac
potential space between these membranes
Fornices –
conjunctival reflections from eyelid to eye
Space between eyelids when open =
palpebral fissure
Tarsal glands embedded in
tarsal plates
modified sebaceous glands –>
secretions increase viscosity of tears & decreases rate of evaporation
Ciliary glands associated with :
eyelash follicles, sebaceous & sweat glands
Orbital septum =
extension of periosteum into the upper & lower eyelids
extends into the eyelids
Bony orbit Objects piercing roof enter
anterior cranial fossa
Bony orbit Bony orbit Objects piercing floor enter
maxillary sinus
Bony orbit Objects piercing medial wall enter
ethmoid air cells
Bony orbit Objects piercing lateral wall enter
r temporal fossa
Bony orbit Objects piercing superior orbital fissure enter
middle cranial fossa
Supraorbital notch/foramen
Supraorbital n. (branch of CN V1) & a.
Inferior orbital fissure
Infraorbital n. & zygomatic n. (branch of CN V2) & a.
Infraorbital foramen
Infraorbital n. (branch of CN V2) & a.
Ant. ethmoid foramen
Ant. ethmoidal n. (branch of CN V1) & a.
Post. ethmoidal foramen
Post. ethmoidal n. (branch of CN V1) & a.
Ophthalmic a. is a branch off the
the ICA
Supraorbital a. branch off
ophthalmic a.
Infraorbital a. branch off .
maxillary a
The eyeball occupies the anterior part of the orbit.
Its rounded shape is disrupted
anteriorly, where it bulges outward.
This outward projection represents about 1/6 of the total area of the eyeball while the rest of the globe is approximately 5/6 of the total area
The eyeball has three layers (or tunics)
fibrous (outer/external) layer
vascular (middle) layer
inner (internal) layer
Sclera
posterior 5/6 of outer layer (white part); the sclera is the important attachment point for the extrinsic eye muscles
Cornea
anterior 1/6 of outer layer (transparent)
Choroid - middle eye
thin middle layer of ciliary aa. & vorticose vv.
Ciliary body - middle eye
smooth m. around lens for accommodation
Iris - middle eye
colored smooth m. behind cornea controlling pupil size
Pupil - middle eye
adjustable aperture thru which light enters eye
middle eye
Remember this is the vascular layer
Vorticose vv. drain
choroid from each posterior quadrant – drain into superior and inferior ophthalmic vv.
Inner eye This is the nervous
visual” layer
Retina - inner eye
neural layer of eye which receives light rays
Macula lutea - inner eye
oval region of retina for visual acuity (yellow in color thus only visible with red-free light)
Optic disc – inner eye
regions where CN II & retinal vessels enter/exit
Fovea centralis - inner eye
most acute vision site at center of macula
Refractive Media of the Eye - Cornea
largely responsible for refraction of light in the eye
Refractive Media of the Eye - Lens focuses
light rays & near or distant objects on retina
Refractive Media of the Eye - Aqueous humor –
watery filling anterior to lens
Refractive Media of the Eye - Vitreous humor (body) –
gelatinous filling posterior to lens
Lacrimal Apparatus - Lacrimal gland – produces
lacrimal fluid (tears); flows across eye inferomedially to lubricate it
Lacrimal Apparatus - Lacrimal canaliculi
transports tears to lacrimal sac
Lacrimal Apparatus - Lacrimal sac
drains tears to nasolacrimal duct
Lacrimal Apparatus - Nasolacrimal duct – drains
tears thru nasolacrimal canal (under infr. nasal concha)
Levator palpebrae superioris m
raises upper eyelid
Superior rectus m. –
elevates & adducts eye
intorsion - also rotates eyeball medially
Inferior rectus m. –
depresses & adducts eye
extorsion - eye (also rotates eyeball laterally)
Lateral rectus m. –
abducts eye
Medial rectus m. –
adducts eye
Superior oblique m. –
depresses & abducts eye
(Intorsion) eye (also rotates eyeball medially
Inferior oblique m. –
elevates & abducts eye
extrosion) eye (also rotates eyeball laterally
All of these muscles, with the exception of
levator palpebrae superioris, insert into the sclera
CN III
Supplies LPS, SR, MR, IR, & IO mm.
Carries parasymp. to ciliary ganglion
CN IV
Supplies SO m.
CN VI
Supplies LR m
Testing the Extraocular Muscles - each muscle tested
individually
Determines if damage is to CNs or single muscle, or single CN
Eye is placed in positions of strongest - test
individual m. pull
The position of abduction/adduction is opposite
of m. action
Part of the testing is in the
vision of seeing the light – CN II
Eye can be placed neutrally to test
lat. & med. rectus mm.
Eye must be abducted to test
supr. & infr. rectus mm.
Eye must be adducted to test
supr. & infr. oblique
Optic n
Nerve fibers between the eye & chiasm
Optic chiasm
X-shaped intermingling of nerve fibers
Optic tract
Nerve fibers from chiasm to brain
2 visual fields:
Temporal retina
Nasal retina
Temporal vision crosses over at
chiasm
Nasal vision remains
ipsilateral
Visual field testing
detects blindness
Location of lesion determines deficit
Optic n. lesion
results in total blindness in affected eye
Optic chiasm lesion
produces loss of peripheral vision
Optic tract lesion
results in ipsilateral nasal visual field loss & contralateral temporal visual field loss
Ciliary Ganglion receives p-symp from
from CN III
Sends short ciliary nn. to posterior eye
Ciliary ganglion supplies p-symp to
Supplies p-symp. to:
Ciliary m.
Pupillary sphincter m.
Ciliary ganglion- supplies Symp. to
pupillary dilator m. via internal carotid plexus
Ciliary ganglion receives
3 types of fibers from 3 separate sources
Sensory fibers from CN V1 via the sensory or nasociliary root of the ciliary ganglion
Presynaptic parasympathetic fibers from CN III via the parasympathetic or oculomotor root of the ciliary ganglion
Postsynaptic sympathetic fibers from the internal carotid plexus via the sympathetic root of the ciliary ganglion
Pupillary Light Reflex tested with
pen light
Pupillary light reflex Tests
CN II & CN III pupillary responses
Eyes tested individually
Light enters 1 eye, both pupils should constrict
CN III p-symp. lesion
Pupil remains dilated
CN V1 in the Orbit- 3 divisions
Nasociliary n
Frontal n.
Lacrimal n.
Nasociliary n
Ethmoidal & infratrochlear nn.
Long ciliary nn. (sensory & symp.) to posterior eye
Frontal n
Supraorbital & supratrochlear nn.
Lacrimal n.
Supplies lacrimal gland & conjunctiva
Arteries of the Orbit & Eye - Ophthalmic a. –
gives rise to all aa. of eye
Arteries of the Orbit & Eye - Posterior ciliary aa. –
supplies outer & middle layers of eye
Arteries of the Orbit & Eye - Central retinal a.
supplies inner layer of retina
Arteries of the Orbit & Eye - Ethmoidal aa. –
supply ant. cranial fossa, nose, & sinuses
Arteries of the Orbit & Eye - Supraorbital a. –
supplies central region of forehead
Arteries of the Orbit & Eye - Supratrochlear a. –
supplies medial region of forehead
Arteries of the Orbit & Eye - Lacrimal a.
Lacrimal a. – supplies lacrimal gland
Veins of the Orbit & Eye - Superior ophthalmic v. –
from upper med. orbit
Veins of the Orbit & Eye - Inferior ophthalmic v.
from lower med. orbit
Both anastomose with facial v. & drain to cavernous sinus
Veins of the Orbit & Eye - Central retinal v.
from retina & drains to cavernous sinus
Veins of the Orbit & Eye - Vorticose vv. –
from vascular layer of eye
Drains into superior & inferior ophthalmic vv.
Support for eyelids mainly
connective tissue
Orbital septum extension of
periosteum
Superior tarsus
dense connective tissue for eyelid support. Superior has muscle fibers from levator palpebrae superioris (smooth muscle portion) Inserts into orbital septum
Tarsus lateral attachemnt
lateral palpebral ligament - goes onto zygomatic bone
Ciliary glands
associated with eyelashes.
Autonomics get to lacrimal gland via
optic tract
Parasymp to lacrimal gland:
greater petrusal –> pterygopalatine ganglia (here it becomes postganglionic) –> maxillary nerve –> zygomatic nerve –> lacrimal nerve
Sympathetics to lacrimal gland
Pre to post occurs in superior cervical ganglion. Postsynaptic ride on internal carotid plexus, go to deep petrusal nerve, joins with greater petrusal.
Sympathetics
anywhere there are blood vessels
Presynaptic sympathetics lcated in
T1
Nerve of pterygoid canal has
both symp and parasymp.
Sympathetic control
Dilator pupilae - attention.
retina
11 or 12 layers
Meningeal layers continue on
optic nerve to eye
lens flips the
image
Vitreous humor
not remade
Periorbita
periosteum lining orbit
Horner’s syndrome
loss of symp function in head. Pupilllary constriction, absence of sweating (also under symp).
Trochlear continues overtop of
levator palpebrae… splits
P-symp in eye
for ciliary muscle and pup sphincter.
