Eyelids, Lacrimal Apparatus, Orbit - 2

true

T/F

lightwaves pass through refractive media of eyeball

cornea → aqueous humor → lens → vitreous humor

false

T/F

lightwaves pass through refractive media of eyeball

cornea → aqueous humor → lens → iris

cornea

primary refractory medium of eyeball, bends light to greatest degree, focuses an inverted image on light-sensitive retina

aqueous humor

occupies anterior segment of eyeball

aqueous humor

fills chambers of eye, produced by ciliary processes

aqueous humor

provide nutrients for avascular cornea and lens, produced and drained continuously into venous system via Canal of Schlemm

anterior chamber of eye

between cornea anteriorly and iris or pupil posteriorly

posterior chamber of eye

between iris or pupil anteriorly and lens and ciliary body posteriorly

vitreous humor

watery fluid enclosed in meshes of vitreous body

vitreous humor

holds retina in place and supports lens, constant and never replaced

vitreous body

transparent jelly-like substance in posterior 4/5 of eyeball posterior to lens

lens

posterior to iris and anterior to vitreous humor of vitreous body

lens

highly elastic capsule is anchored by zonular fibers to the encircling ciliary processes

lens

transparent, biconvex structure enclosed in transparent capsule

lens

its convexity varies to fine-tune focus of objects on retina

limbal plexus

removes aqueous humor, drains to both tributaries of vorticose and anterior ciliary veins

glaucoma

obstruction in drainage of aqueous humor that damages optic nerve

levator palpebrae superioris

most superior muscle in orbit, broadens to wide bilaminar aponeurosis as it approaches distal attachments

levator palpebrae superioris

antagonist of superior half of orbicularis oculi, sphincter of palpebral fissure

recti muscles

originate at common tendinous ring, actions are elevate, depress, adduct, abduct

recti muscles

secondary actions include medial rotation and elevation by superior rectus and lateral rotation and depression by inferior rectus

true

T/F

both superior and inferior rectus muscles have a secondary action of adduction

false

T/F

both superior and inferior rectus muscles have a secondary action of abduction

superior oblique

muscle from apex region but tendon traverses trochlea inside superior medial orbital rim

superior oblique

primary medial rotator, secondary function is depressor of eye

inferior oblique

only muscle to originate from anterior part of orbit

inferior oblique

primary lateral rotator, secondary function is elevator of eye

true

T/F

both superior and inferior oblique muscles have a secondary action of abduction

false

T/F

both superior and inferior oblique muscles have a secondary action of adduction

optic nerve

convey purely sensory nerves, surrounded by extension of cranial meninges and subarachnoid space

optic nerve

mediates afferent limb of pupillary light reflex, nerve fibers exit orbit via optic canals

true

T/F

course of optic nerve

enters from middle cranial fossa by passing through optic canal, runs forward and pierces sclera at posterior pole of eyeball

false

T/F

course of optic nerve

enters from inferior cranial fossa by passing through optic canal, runs forward and pierces sclera at posterior pole of eyeball

false

T/F

course of optic nerve

enters from inferior cranial fossa by passing through optic canal, runs forward and pierces sclera at anterior pole of eyeball

ophthalmic nerve

passes through superior orbital fissure and immediately divides to nasociliary, frontal, and lacrimal nerves

nasociliary nerve

enters orbit through lower part of superior orbital fissure

nasociliary nerve

crosses above optic nerve → upper margin of medial rectus → divides to anterior ethmoidal and infratrochlear nerves

nasociliary nerve

communicating branch to ciliary ganglion

frontal nerve

enters orbit through upper part of superior orbital fissure → upper surface of levator palpebrae superioris → divides to supratrochlear and supraorbital

lacrimal nerve

enters orbit through upper part of superior orbital fissure → upper border of lateral rectus → joins zygomaticotemporal nerve

oculomotor nerve

divides to 2 ramus

superior ramus of oculomotor nerve

supplies superior rectus and levator palpebrae superioris

inferior ramus of oculomotor nerve

supplies inferior rectus, medial rectus, and inferior oblique

trochlear nerve

enters orbit through upper part of superior orbital fissure, supplies superior oblique

abducens nerve

enters orbit through lower part of superior orbital fissure, supplies lateral rectus

ciliary ganglion

group of postsynaptic parasympathetic nerve cell bodies, between optic nerve and lateral rectus

ciliary ganglion

receives sensory fibers from CN V1 via sensory or nasociliary root

ciliary ganglion

receives presynaptic fibers from CN 3 via parasympathetic or oculomotor root

ciliary ganglion

receives postsynaptic sympathetic fibers from internal carotid plexus via sympathetic root

short ciliary nerves

branch of ciliary ganglion, carries parasympathetic and sympathetic fibers to ciliary body and iris

long ciliary nerves

branch of ciliary ganglion (nasociliary nerve) that pass to eyeball, convey postsynaptic sympathetic fibers to dilator pupillae and afferent fibers from iris and cornea

posterior and anterior ethmoidal nerves

arise in orbit and exit via openings in medial wall of orbit

Adie’s pupil

dilated pupil even in presence of bright light, results in damaged ciliary ganglion

ophthalmic artery

branch of internal carotid artery, enters orbit through optic canal with optic nerve and crosses optic nerve to reach medial wall of orbit

central artery of retina

branch of ophthalmic artery, pierces meningeal sheaths of optic nerve

central artery of retina

branch of ophthalmic artery, arterioles or end arteries provide blood supply to internal aspect of retina

central artery of retina

branch of ophthalmic artery, choriocapillaris supply blood to external aspect of retina

ciliary arteries

branch of ophthalmic artery, supply eyeball

anterior group of ciliary arteries

enters eyeball near corneoscleral junction and continuations of muscular branches of ophthalmic artery

posterior group of ciliary arteries

enters near optic nerve, 6 short posterior ciliary arteries (supply choroid), 2 long posterior ciliary nerves (supplu choroid plexus)

lacrimal artery

supply lacrimal gland, portion of eyelid, and anterior eyeball

supraorbital artery

supplies forehead

supratrochlear artery

supplies scalp muscle and skin

muscular branches

supplies extraocular muscles

infraorbital artery

supplies structure related to orbital floor

ophthalmic vein

pass backward through superior orbital fissure and drain to cavernous sinus

superior ophthalmic vein

from union of supraorbital and supratrochlear veins, communicate with facial vein

superior ophthalmic vein

formed behind medial part of upper lid by 2 tributaries: facial and supraorbital

superior ophthalmic vein

runs posteriorly with ophthalmic artery, empties to cavernous sinus

inferior ophthalmic vein

begins at anterior part of floor of orbit and runs backwards

inferior ophthalmic vein

communicates with pterygoid venous plexus through inferior orbital fissure and drains to cavernous sinus

vortex or vorticose veins

from vascular layer of eyeball drain to inferior ophthalmic vein

central vein of retina

runs with artery in center of optic nerve

central vein of retina

pierces optic nerve behind eyeball and drains to cavernous sinus

scleral venous sinus

encircles anterior chamber of eyeball where aqueous humor is returned to blood circulation

tenon’s capsule or fascia bulbi

encases globe and separates it from orbital fat, outermost covering

tenon’s capsule or fascia bulbi

extends from optic nerve to corneoscleral junction, thickened anteriorly at attachment of recti muscles forming a fascial ring

tenon’s capsule or fascia bulbi

surrounds eyeball except area of cornea

tenon’s capsule or fascia bulbi

provide eyeball with socket for free movement

tenon’s capsule or fascia bulbi

between conjunctiva and episclera, merges anteriorly in limbal area

tenon’s capsule or fascia bulbi

pierced by optic nerve, vortex veins, ciliary vessels and nerves, EOM

tenon’s capsule or fascia bulbi

envelope of elastic connective tissue that fuses posteriorly with optic nerve sheath and anteriorly with thin later of intermuscular septum

tenon’s capsule or fascia bulbi

as a muscle pulley, strongest attachment at limbus

tenon’s capsule or fascia bulbi

inner surface is smooth and separated from sclera by periscleral lymph

tenon’s capsule or fascia bulbi

anterior 1/3 adheres to back of ocular conjunctiva

tenon’s capsule or fascia bulbi

middle 2/3 sends fascial extension to recti and oblique eye muscles

tenon’s capsule or fascia bulbi

posterior 1/3 in contact with orbital fat and becomes continous with sheath of optic nerve

sub-tenon space

potential space between tenon’s capsule and sclera

orbital fat pad

adipose that surrounds EOM, optic nerve, and globe

orbital fat pad

under, over, and behind eyeball to protect and cushion it

central or conal

fat within muscle cone

peripheral or extraconal

fat outside muscle cone

orbital fat pad

occupy space between main parts of orbit

orbital fat pad

upper eyelid consists of 2 fat pads separated by trochlea

nasal or medial fat pad

white in color, contains more fibrous tissue

preaponeurotic or central fat pad

larger pad on muscular portion of levator palpebrae superioris

preaponeurotic or central fat pad

rich yellow (carotenoids) and less fibrous tissue

orbital periosteum or periorbita

orbit lining of bones forming orbit

orbital periosteum or periorbita

attachment for muscles, tendons, and ligaments

orbital periosteum or periorbita

continuous at optical canal and superior orbital fissure with periosteal layer of dura mater