Orbit and Eye: Embryology Flashcards
neural ectoderm
evaginations of forebrain neuroectoderm
- forms optic vesicles
- invaginate on themselves to form optic cup
optic stalk
connection of forebrain to optic cup
choroid fissure
ventral surface of optic cup
-carries hyaloid essels
optic cup
forms retina - optic nerve
surface ectoderm
lens placode - lens vesicle - lens
mesenchyme
forms fibrous and vascular layers
outer layer optic cup
pigmented layer of retina
inner layer of optic cup
all neural layers of retina
nerve fibers from retina
migrate through choroid fissure to form CN II
week 7
choroid fissure closes
congenital retinal detachment
inner and outer layer optic cup fail to fuse
separation of pigmented and neural layers
iris and ciliary body embryo
outer - vascular mesenchyme surrounding optic cup
inner - optic cup (no neural)
infants
born with blue-gray eyes - lack of melanin
will migrate in first 6-10 months
congenital atresia of pupil
iridopupillary membrane degenerates after week 15
-failure of membrane to degenerate
abnormally closed pupil
coloboma
failure of choroid fissure to fuse during 7th week development
hole in structure of eye
sclera and cornea embryo
from fibrous layers of mesenchyme surrounding optic cup
choroid embryo
vascular layer of mesemchyme surrounding optic cup
aqueous and vitreous humors of eye embryo
form from cell deah in eyeball
vitreous humor embryo
likely from neural crest cells
lens embryo
lens vesicle
congenital aphakia
agenesis of lens placode
absence of lens in eye
extrinsic eye muscles embryo
mesoderm of myotomes
ophthalmic artery
from internal carotid artery
-enters optic canal
branches of ophthalmic artery
central retinal artery short posterior ciliary a long posterior ciliary a anterior ciliary aa lacrimal a supraorbital a posterior ethmoidal a anterior ethmoidal a medial palpebral a supratrochlear a dorsal nasal a
blood to retina
central retinal artery
-runs with CN II
blood to choroid
short posterior ciliary a
blood to ciliary body/iris
long posterior ciliary a
anterior ciliary arteries
venous drainage eyeball
central retinal vein - cavernous sinus
vorticose veins - drain choroid, ciliary body, iris
superior/inferior ophthalmic veins - exit superior/inferior orbital fissures > cavernous sinus and pterygoid venous plexus, respectively
thrombophlebitis
of cavernous sinus
may send clot to central retinal vein
-vision loss
increased intracranial pressure
meninges and CSF continue along CN II
-may affect eye
optic n, central retinal a, central retinal v - compressed
papilledema
retinal edema
-occlusion of central retinal vein
movements of eye
adduction abduction elevation depression extortion - lateral rotation intortion - medial rotation
levator palpebrae superioris
eyelid
medial rectus
common tendinous ring - medial surface eyeball
adduct eye
CN III
lateral rectus
common tendinous ring - lateral surface of eyeball
abduct eye
CN VI
superior rectus
common tendinous ring - superior surface eyeball
elevate, adduct, intorsion
CN III
inferior rectus
common tendinous ring - inferior surface eyeball
depress, adduct, extorsion
CN III
inferior oblique
anterior portion floor orbit - inferior surface eyeball
elevate, abduct, extorsion
CN III
superior oblique
common tendinous ring - superior surface eyeball
-passes through trochlea
depress, abduct, intorsion
CN IV
oculomotor nerve
CN III GSE, GVE-P
parasympathetic to ciliary ganglion
diplopia
one eye positioned differently
oculomotor nerve palsy
ptosis or complete closure of eye
-lose levator palpebrae superioris
diplopia - down and out
dilated pupil
loss of accomodation
trochlear nerve
CN IV GSE
to superior oblique muscle
trochlear nerve palsy
diplopia - elevated and adducted
loss of depression when eye fully adducted
abducens nerve
CN VI GSE
to lateral rectus muscle
abducent nerve palsy
diplopia - loss of abuction
optic nerve
CN II - SSA vision
covered in meninges
optic nerve fibers are axons of ganglion cell layer of retina which pass through optic disc and exit lamina cribrosa of sclera posterior
CN V1
ophthalmic nerve
GSA
branches:
- nasociliary
- frontal
- lacrimal
nasociliary nerve
branch of V1
- sensory root to ciliary ganglia
- short ciliary nn
- long ciliary nn
- posterior ethmoidal n
- anterior ethmoidal n
- infratrochlear n
frontal nerve
branch of V1
- supratrochlear n
- supraorbital n
lacrimal nerve
branch of V1
- sensory to lacrimal
- carry postganglionic PS and S to lacrimal gland
ciliary ganglion
between lateral rectus and optic nerve
-postganglionic PS cell bodies
sensory - nasociliary nerve
PS - motor root from oculomotor
S - motor root from internal carotid plexus
PS to intraocular eye muscles
preganglionic - edinger westphal
-fibers with oculomotor nerve
postganglionic - ciliary ganglion
-fibers distrubute short ciliary nerves to sphincter pupillae muscle and ciliary muscle
sympathetic to intraocular eye muscles
preganglionic - T1-2
-fibers to SCG
postganglionic fibers - internal carotid plexus
-ciliary ganglia without synapse
distribute short and long ciliary nn - dilator pupillae and superior tarsal muscle
parasympathetic to lacrimal gland
preganglinic - salivatory nucleus
- fibers with greater petrosal nerve CN VII
- synapse at pterygopalatine ganglion
postganglionic - zygomatic nerve V2 and lacrimal nerve V1
increase secretions
sympathetic lacrimal gland
preganglionic - T1-4
-synapse SCG
postganglionic fibers - internal carotid nerve - deep petrosal nerve
greater and deep petrosal nerve merge
-nerve to pterygoid canal
postganglionic distribute zygomatic V2 and lacrimal V1 nn
more watery lacrimal fluid
pupillary light reflex
afferent - CN II
efferent - CN III (GVE-P) - sphincter pupillae m.
both pupils constrict
- direct ipsilateral eye light
- consensual contralateral eye light
corneal reflex
protect eye from foreign object
afferent - CN V1 - pain sensation
efferent - CN VII - orbicularis oculi
puff air - stimulates CN V1
-both eyes blink - direct and consensual
accomodation reflex
function - view near objects
afferent CN II
efferent CN III GSE and GVE-P
direct and consensual response
3 events:
- ciliary muscles contract - rounding of lens - GVE-P
- pupils constrict - GVE-P
- eyes adduct - GSE
3 events of accomodation
- ciliary muscles contract - rounding of lens - GVE-P
- pupils constrict - GVE-P
- eyes adduct - GSE
