Orbit Flashcards
The _____coverint the eyelid is very thin and continuous with the palpebral conjunctiva
skin
sparse, loose conective tissue that rarely contains fat in the eye
subucatneous tissue
ciliary glands are found in what laere of the eyelid
subcutaneous tissue
ciliar glands are
mixed sebaceous and modifies sweat glands
Zeis glands
sebaceous
Moll glands
modified sweat
if the sebaceous and modifies sweat glands of the eyelid become infected, what forms
a sty
Orbicularis occuli has two portions
palpebral potion and lacrimal portion.
palpebral - integrated with levitator palpebrae superiors
lacrimal - extends from posterior lacrimal crest to the tarsal plates of lids and lacrimal sac, increases the amount of lid contact to the suface of the eyeball
levator palpebrae superioris muscle inserts
into palpebral fascia and skin of upper lid
levator palpebrae euperioris innervated by
GVE fibers of oculomotor nerve (III)
destruction of the oculomotor nerve or one of its branches to levitator palpebrae superiorisresults in
paralysis of this muscle and COMPLETE ptosis
This is ocular nerve palsy
Ocular nerve palsy
complete ptosis, external strabismus, pupillary dilation
tarsal muscle of Muller inserts on
tarsal plate of the upper lid
tarsal muscle innervated by
postganglioinc sympathetic fibers
tarsal muscle affected in what syndrome
horner;s syndrome
cartilagineous plate tied in with the orbital septum
tarsus
Horner’s syndrome involves
paralysis of the tarsal muscle, concomitant SLIGHT ptosis an dmiosis.
enophthalaus and anhidrosis and blushing
the retina is an invagination of
diencephalon
othe ___ formas a firewall between deep and superficial contents of the orbit
orbital septeum
why is the orbital septum important
because the orbit is very closely related to the brain
when we suffer traumatic facial injure what do we care about repairing first
want to line up the teeth and the orbit
Palpebral fascia is composed of
tarsus and orbital septum
What do the tarsal glands secrete, and why is ti important
an oily secretion which helps to resist the overflow of tears at the palpebral margin
tarsus
comprised of two dense fibrous connective tissue plates in the upper and lower margins of the lids.
both are attached to the medial and lateral palpebral ligaments, and are semilunar shaped in order to conform the curvature of the eyeball
what happens if you throw off the margin of the eyelids
like when you mess up your windshield wipers. lids no longer uniformly moving across the surface of the eye
Continuous with periosteum at the superior and inferior orbital margins, attached to tarsal plates,
orbital septum
superior palpebral fascia is pierced by
levator palpebrae superioris m
Conjunctiva
thin membrane that lines the back of the eyelids (palpebral)and front of the eyeball (bulbar)
palpebral conjunctiva
is opaque and highly vascular membrane. covers posterior surface of lids,
bulbar conjunctiva is
transparent membrane loosely attached to the eyeball.
semilunar fold
crescent shaped membranous fold formed by the bulbar conjunctiva t the MEDIAL can thus. forms the lateral border of the triangularly shaped lacrimal lake at the center of which is the lacrimal carunck
why can’t swelling of the lid get from upper lid to lower lid on the medial side
because of the orbital septum at the medial side.
what gland produces tears to keep the surface of the cornea moist
lacrial gland
parasympathetic innervation of lacrimal gland
superior salivatory nucleus–> facial nerve–> freater superficial petrosal nerve and vidian nerve –> sphenopalatine ganglion
post ganglionic parasympathetic fivers course via maxillary, zygomatic and lacrimal nerves
Sumpathetic innervation of the lacrimal gland
post ganglionic sympathetic fibers from superior cervical ganglion, –> internal carotid plexus–> deep petrosal nerve, –> fuses with greater superficial petrosal to form vidian nerve–> through sphenopalatine ganglion and distribute to lacrimal gland via maillary zygomatic lacrimal nerve route.
may even reach it in lacrimal plexus in adventitia of lacrimal artery
lacrimal canaliculi
small L shaped tube located at the palpebral margins of each led at the medial canthus. The two canaliculi straddle the posterio aspect of the medial palpebral ligament
function of lacrimal canaliculi
drain tears from the surface of the eyeball to the superior lateral aspect to the lacrimal sac
lacrimal sac
elongated sac receives the lacrimal canaliculi and is continuous inferiorly with nasolacrimal duct
nasolacrimal duct courses through
nasolacrimal canal. and opens into inferior meatus 1cm posterior to the anterior edge of the inferior concha (drains into the nasal cavity)
Bony orbit comprised of what bones
frontal, zygomatic, maxilla, each are common points of fracture
supraorbital margin of orbit
frontal bone
supra orbital notch
lateral margin of orbit
zygomatic bone, associated with orbital tubercle, the point or attachment of lateral palpebral ligament
infraorbital margin
zygomatic and maxilla bones
infraorbital foramen at midpoint
margins are ____ than walls
thicker
herniation of orbital contents herniate where
maxillary sinus - here we are concerned with infection
fractures of the orbit can compress what structure
the optic nerve
Blow out fractures of the floor of the orit
may be due to trauma to the front of the eyeball or a depressed fracture of the zygomatic bone, which is displaced medially
cause herniation of certain orbital structures into maxillary sinus
Le Forte Type I
transverse fractures of the maxillae just above alveolar processes
Leforte Type II
pyramidal sheped fractures of maxillae usually involving part of the medial margin of one of the orbits
LeForte Type III aka
craniofacial dysjunction
Le Forte Type III
extensive tranverse fractures of face involving many facial bones and both orbits. basically the face has been separated from th ease of the skull
trauma to anterior globe pushes it through
the floor of the orbit
Periobita is continuous with
endocranium of middle cranial fossa (endosteal dura)
is the periosteum of the orbit
endosteal dura is continusouw with
periosteal fascia, palpebral fascia and periosteum of the orbital rim
sheath of the optic nerve is
dura
meningeal dura is continuous with
sheet of the optic nerve.
periorbita and bulbar fascia are usu fused at optic canal and SOF, separating
the orbital cavity from the middle cranial fossa
bulbar sheath or fascia
covrs optic nerve and entire eyeball except cornea
Abducens palsy
increaased ICP may compress abducens nerve and result in paralysis of lateral rectus mucle SUNDOWN GAZE (down and in)
paralysis of trochlear nerve
superior oblique
inability to adduct and depress affected eye
oculomotor palsy
complete ptosis,
inability to abduct and elevate eye (SR)
inability to adduct affected eye (MR)
inability to abduct and dprese affected eye(IR)
inability to adduct and elevate affected eye (IO)
Oculomotor palsy passive sign
external strabisms
SO causes eye to look
down and in.
positions of the eye where that muscle is maximally active
cardinal signs of gaze
V1 Lacrimal nerve fiber type
GSA
V1 fontal nerve
GSA terminates as supraorbital and supratrochlear n
V1 nasociliary nerve
GSA nerve to eyeball
V1 anterior ethmoidal nerve
supplies antero superior nasal cavity and part of the outer nose
Corneal Reflex - nerves
in by 5, out by 7
Direct and consensual Corneal reflexes stimulus receptor afferent fibers sensory nucleus motor nucleus efferent fibers effector response
protective reflex lightly touching cornea nakedd nerve endings in cornea nasociliary nerve, especially long ciliary nerves descending nucleus of V facial nucleus facial nerve orbicularis oculi muscle blinking (both direct and consensual
primary sensory nerve for the eyeball
nasociliary nerve
conjugate gaze
eyes move in parallel
the only normal disconjugate gaze
convergence - cortically mediated
accommodation
focusing in a near field.
eyes converge and constrict
Occulomotor nerve fiber types
GSE to the extra ocular muscles
GVE-P to ciliary muscles of lens and sphincter pupillae muscle of iris
ciliary ganglion fiber types
GVE-P
postganglionic sympathetic
GSA
Ciliary ganglion located between
lateral rectus and optic nerve
Cortically mediated responses that are components of accommodation
pupillary constriction and thickening of the lens
pupillary constriction and thickening of the lens are responses of what branch of ans
parasympathetic
Paralysis of oculomotor results in
external strabismus
complete ptosis
dilated and unreactive pupils
paralysis of trochlear results in
inability to aDduct and depress the affected eye
pt tends to tilt his head away from the affected eye
paralysis of abducens nerve results in
inability to aBduct the affected eye
diplopia due to internal strabismus
Chief artery of the orbit, usually the first branch of ICA
ophthalmic artery
arteries that supply optic nerve, what artery do they arise from
posterior ciliary a, central retinal a
from ophthalmic artery
main blood supply to the retina
Central retinal artery
terminal branches of arteries in the retina are ______ meaning that _________,
we see these terminal branches where>
end arteries
there is not a lot of anastomotic connections
we see these with our ophthalmoscope
tehe central retinal artery supplies the four quadrants of the retina through
upper and lower temporal branches and upper and lower nasal branches.
Direct light reflex
elicited by shining a bright light in an eye resulting in ipsilateral pupillary constriction, which is mediated at the level of the brainstem via the parasympathetics
Consensual light reflex
shining a bright light in one eye will result in pupillary constriction of the contralateral eye
degree of constriction may be less than that in the ipsilateral eye.
Direct and consensual light reflex differ in the fact that
the consensual light reflex pathway has the addition of the posterio r commisure to get the reflex
important structrual components of the pupillary light reflex
pretectum and the posterior commisure
pathway for direct light reflex
retina–>optic nerve–> optic tract–>brachium of superior colliculuc–> superior colliculus–>pretectum–>edinger westphal nucleus–> oculomotor nerve–> ciliary ganglion–> pupillary constrictor muscle–> ipsilateral pupillary constriction
pathway for indirect light reflex
retina–> optic nerve–> optic tract–>brachim of superior colliculus–>superior colliculus–> pretectum–> POSTERIOR COMMISURE–> opposite side edinger westphal nucleus–> opposite oculomotor nerve–> opposite ciliary ganglion–> pupilary constrictor muscles–> contralateral pupilary constrition
pupillary dilation response
decrease in amount of light reaching retina results in bilateral reflex diction of the pupils
pupillary dilation response mediated through
brainstem and upper spinal cord
horner;s sydrome
interruption of the pupillary dilation response. characterized by ipsilateral pupillary constriction, slight ptosis and anhydrous and blushign
pupilary dilation response path
decreased light–> retina–>optic nerve–>superior colliculus–> pretectum–>reticular fromation–> lateral reticulospinal tract–> preganglionic sympathetic neruons at T1–> back to head –> superior cervical ganglion–> pupillary dilator muscles
response is pupillary dilation
Triad of accomodation
convergence of gaze
pupillary constriction
thickening of the lens
Accommodation is a ______ mediated response
cortically mediated
from frontal eye field of frontal lobe and projects to the midbrain
is accommodation a reflex
no
Accommodation is the only naturally occurring_____gaze
disconjugate
Accommodation path
frontal eye field–> corticotectal fibers–> superior colliculus–> edinger westphal and oculomotor nucleus
edinger westphal–> ciliary ganglion –> pupillary constriction and thickening of lens
oculomotor nucleus–> convergence of gaze (dysconjugate gaze)
Pretectum is a critcal link
direct light response
ILCC at T1 is a critical link
pupillary dilation
cortically mediated response
accomodation
posterior commissure
consensual light reflex
horners syndrom
pupillary dilation
convergence of gaze, pupillary constriction, thickening of lens
triad of accommodation
in by two out by 3
pupillary response
in by 2 out by sympathetic branch of ciliary ganglion from SCG
pupillary dilation
corticotectal fibers and edinger wetphal and oculomotor nuclei
accomodation
Argyll Robertson pupil aka
prostitutes sign
argyll robertson pupil definition
accommodating but unreactive
argyll robertson pupil cause
syphilis infection
due to destruction of pretectum (important in light reflex but not in accommodation)
the pretectum is important in ______ but not in ______
light reflex, but not in accomodation
Holmes Adie pupil aka
tonic adie pupil
Holmes Adie pupil definition
benign condition which may be due to lesion of ciliary ganglion
slow constriction on convergence
Homes aide pupil and parasympathomimetic drus
parasympathomimetic drugs constrict the tonic pupil - no effect on normal pupil
papilledema
Increased ICP restricts venous return from the retina
the concomitant increase in venous pressure results in edema or swelling of the optic disc
