eye and orbit Flashcards
general orbit
depth 2x width
shaped like a quadrangular pyramid w/base facing anterolateral and apex posteromedial
contralateral medial walls parallel
contralateral lateral walls perpendicular
orbital axis
long axis thru orbit oriented 45 degrees to one another
optical axis
long axis thru globe parallel to medial walls of orbit
bones of orbit
frontal maxilla sphenoid lacrimal ethmoid palatine zygomatic
apex of orbit
lesser wing of sphenoid surrounding optic canal
base
formed by the orbital margin and orbital opening
orbital margin
frontal
zygomatic
maxilla
thickened to provide support and protection to eye
roof of orbit
frontal bones and some spehnoid
separated orbit from ant cranial fossa
has fossa for lacrimal gland
floor of orbit
maxilla bone- separated orbit from maxillary sinus
zygomatic
palatine
medial wall of orbit
separates orbit from sphenoid and ethmoidal air sinuses ethmoid lacrimal maxilla lacrimal fossa
lateral wall of orbit
zygomatic bone
sphenoid- greater wing
optic canal
II, ophthalmic a
superior orbital fissure
III, IV, V1, IV
superior ophthalmic v
inferior orbital fissure
inf opthalmic v
infraorbital a,v,n
sygomatic nn
ant ethmoidal foramen
ant ethmoidal a, n, v
post ethmoidal foramen
post ethmoidal a,n,v
nasolacrimal canal
nasolacrimal duct
blowout fracture- inferior
can involve maxillary sinus
inf rectus m trapped -> diplopia
enophthalmos due to fat
blowout fracture- medially
enophthalmos due to fat
can involve sphenoidal and ethmoidal air sinuses
blowout fracture-roof
can involve ant cranial fossa
orbital tumors
tumors in sphenoidal or ethmoidal sinuses or middle cranial or infratemporal fossas can erode thin walls of orbit or pass thru foramen
exopthalmos
periorbital fasica
lines bones of orbit
continuous w/periostreal dura at optic canal and superior orbital fissue
continuous w/orbital septum anteriorly
continuous w/muscular fascias of extraoccular eye mm
fat and fascias of orbit
periorbital fascia mm fascias check ligaments fascial sheath of eyeball orbital fat
check ligaments
medial and lat
attach to med and lat orbit walls
limit abduction and adduction
prevent post retraction of eyeball by rectus mm
fascial sheath of eyeball
aka tenons capsule or fascia bulbi
thin membrane surrounding eyeball external to sclera
continuous w/muscular fascia of extraoccular eye mm
separates eyeball from orbital fat
orbital fat
cushion
lubrication
protection
w/anorexia eyes become sunken
eyelids
moveable folds of skin and CT which cover eye to protect spread lubrication over cornea
structure of eyelid
skin loose CT orbicularis oculi and levator palpebrae superioris mm tarsal plate palpebral conjuctiva
tarsal plate
dense CT for structural support of eyelid
orbital septum
medial and lateral palbebral ligaments
orbital septum
part of tarsal plate
fibrous membrane connecting tarsi to margins of orbit
fnx to contain orbital fat w/in orbit
limit spread of infection btwn face and orbit
medial palpebral lig
connects tarsi to medial wall of orbit
lateral palpebral lig
connects tarsi to lateral wall of orbit
glands associated w/eyelid
tarsal/sebaceous glands
galnds of Zeis (smaller sebaceous)
glands of Moll (sweat)
glands become obstructed
can get chalazion or hordeoum cysts
orbicularis oculi
sphinchter m of eyelid
VII
therefore damage to VII cannot close eyelid completely
levator palebrae superioris
lesser wing of sphenoid skin of sup eyelid elevates sup eyelid III sup portion attaches to sup tarsal plate innervated sympathetically
III lesion
ptosis
horners syndrome
ptosis due to loss of sympathetics to superior tarsal portion of LPS
palpebral conjunctiva
epi of internal eyelid
bulbar conjunctiva
outer epi of sclera
conjunctiva sac
btwn palebral and bulbar conjunctiva
opens at palpebral fissure
conjunctival fornices
sup and inf
formed where bulbar and palpebral conjuctiva are continuous
lacrimal apparatus
lacrimal gland
lacrimal cannaliculi
lacrimal sac
nasolacrimal duct
lacrimal galnd
compound tuboalveolar gland
located in lacrimal fossa in superolateral orbit
secretes lacrimal fluid into conjunctival sac
lubrication and antibacterial
lacrimal cannaliculi
located in medial angle of eye
begin at lacrimal papilla
lacrimal punctum is opening
lacrimal sac
receives fluid from lacrimal cannaliculi
nasolacrimal duct
drains lacrimal fluid to nasal cavity
flow of tears
lacrimal glans -> conjunctical sac-> surface of eye -> lacrimal papillae w/puncta -> cannaliculae -> lacrimal sac -> nasolacrimal duct
eye
3 tunics
lens
vitreous and aqueous chambers
external fibrous tunic
sclera
cornea
sclera
tough opaque fibrous layer covering post 5/6 of globe
provides structural support for eye and mm attachment
cornea
avascular, dehydrated, transparent layer covering ant 1/6 of globe
provides most of eyes refractile capabilities
numerous pain receptors w/in cornea
corneal neurovascularization
blood vessels grow into corneal stroma secondary to hypoxia
middle vascular tunic
aka uvea choroid iris ciliary body ciliary m
choroid
highly vascualrized, loose CT, located deep to sclera
provides vascular supply to fibrous layers and outermost layers of retina
contains melanocytes which produce melanin to absorb photons
iris
central aperature forms pupil
controls amount of light entering pupil
sphincter pupillae m
dilator pupillae
sphincter pupillae
reduces diameter of pupil (meiosis)
parasympathetic via III
dilator pupillae
increases diameter of pupil (mydriasis)
sympathetics