Eyelids, Lacrimal Apparatus, Orbit - 1

orbit

contains eyeball and its appendages

orbital region

includes upper and lower eyelids and lacrimal apparatus

eyelids

movable folds that cover eyeball anteriorly

eyelids

keep cornea moist by spreading lacrimal fluid

eyelids

covered externally by thin skin and internal by peripheral conjunctiva

anterior lamella of eyelids

skin and orbicularis oculi

middle lamella of eyelids

orbital septum

posterior lamella of eyelids

tarsal plates, superior eyelid muscles, conjunctiva

skin

thinnest in body with minimal subcutaneous tissue, devoid of fat, continuous with conjunctiva at lid margin

skin

has multiple tarsal gland that secrete oily material to reduce evaporation of tears

orbicularis oculi

elliptical striated muscle arranged in concentric bands

orbicularis oculi

involved in blinking and eyelid closure, palpebral, lacrimal, and orbital parts

palpebral part of orbicularis oculi

arising from medial palpebral ligament, gently close eyelids to keep cornea from drying

lacrimal part of orbicularis oculi

passing posterior to lacrimal sac, draws eyelid medially, aids in tear drainage

orbital part of orbicularis oculi

overlying orbital rim, tightly close eyelids to protect eyeball against glare and dust, medially attached to frontal bone and maxilla

eyelashes

found in margins of lids that operate as dust catchers, protecting eye from debris that can obstruct vision or cause infection or injury

canthus

medial and lateral angles of eye

canthus

inner and outer edges formed by medial and lateral palpebral commisures of junctions of superior and inferior eye

orbital septum

fibrous membrane that spans tarsi to margins of orbit and continuous with periosteum

orbital septum

keep orbital fat contained and spread limit of infection

orbital septum

large part of posterior fascia of orbicularis oculi muscle

tarsal plate

formed by dense fibrous tissue representing thickened extension of orbital septum

tarsal plate

anchors roots of eyelashes and contain tarsal glands

tarsal plate

attach to periosteum via canthal tendons

true

T/F

each eye has superior and inferior tarsal plate

false

T/F

each eye has superior tarsal plate

levator palpebrae superioris

thin muscle in bony orbit above eyeball, extraocular or facial muscle

levator palpebrae superioris

extraocular muscle that moves eye by elevating and retracting upper eyelid to have na upward gaze

levator palpebrae superioris

facial muscle that contributes to facial expressions

superior tarsal muscle

smooth muscle in superior eyelid, component of levator palpebrae superioris, elevate upper eyelid

conjunctiva

transparent mucous membrane that lines both inner surface of eyelids and anterior surface of eyeball

conjunctiva

allows eyelid to move smoothly and freely over eye to keep it moist

palpebral conjunctiva

part of conjunctiva, thin and transparent attach loosely to anterior surface of eyeball, continuos with bulbar conjunctiva, and form superior and inferior conjunctival fornices

bulbar conjunctiva

part of conjunctiva, loose and wrinkled over sclera adhere to periphery of cornea

conjunctival sac

space bound by palpebral and bulbar conjunctiva, closed when eyelids are closed and opens via anterior aperture

hordeolum

or stye, inflammation of eyelash follicle or gland of Zeis or Zois, due to bacterial infection

hordeolum

mostly found near eyelash follicle, tenderness, swelling

internal hordeolum

small red painful lump that grows at base of eyelashes affects eyelash follicle

external hordeolum

under eyelids affects Meibomian gland

chalazion

or meibomian gland lipogranuloma

chalazion

swollen lump in above the eyelashes on upper lid

chalazion

blocked oil gland, non-painful nodules, firm, caused by blockage of sebaceous glands

lacrimal gland

exocrine gland above eyeball secretes lacrimal fluid

lacrimal gland

in upper anterolateral part of orbit posterior to orbital septum

lacrimal gland

large orbital part and small palpebral part, opens to lateral part of superior fornix of conjunctiva

lacrimal fluid

physiologic saline with lysozyme that moistens and lubricates surfaces of conjunctiva and cornea, provide nutrients and dissolved oxygen to cornea

excretory ducts of lacrimal gland

conveys lacrimal fluid from lacrimal glands to conjunctival sac

lacrimal lake

at medial canthal region of eye, triangular space where fluid collects

lacrimal canaliculi

2 curved canals that begin as lacrimal punctum in margin of eyelid and open to lacrimal sac

lacrimal punctum

opening of lacrimal canaliculi found on lacrimal papilla at medial end of upper and lower eyelids

lacrimal papilla

small rise in bottom and top of eyelids, at top of eyelids before it ends at corner of eye closest to nose

lacrimal sac

upper dilated end of nasolacrimal duct, reservoir for tears to keep old tears from flooding the tear ducts

nasolacrimal duct

tear ducts, conveys lacrimal fluid to inferior nasal meatus

lacrimal fold

fold of mucous membrane that guards opening of nasolacrimal duct

lacrimal fold

prevents air from being forced up the duct into lacrimal sac when you blow your nose

parasympathetic innervation of lacrimal gland

stimulate secretion of lacrimal fluid

parasympathetic innervation of lacrimal gland

derived from lacrimal nucleus of facial nerve

parasympathetic innervation of lacrimal gland

preganglionic fibers reach pterygopalatine ganglion via nervous intermedius and its great petrosal branch and via nerve of pterygoid canal

parasympathetic innervation of lacrimal gland

synapse on postganglionic parasympathetic fibers travel within zygomatic and zygomaticotemporal branches off the maxiliary nerve to supply gland

sympathetic innervation of lacrimal gland

regulates blood flow through lacrimal gland and glandular secretions

sympathetic innervation of lacrimal gland

from superior cervical ganglion, nerve fibers reach pterygopalatine ganglion via internal carotid plexus and deep petrosal nerve

true

T/F

flow of lacrimal secretion

lacrimal gland → lacrimal ducts → ocular surface → lacrimal puncta → lacrimal canaliculi → lacrimal sac → nasolacrimal duct → inferior nasal meatus → nasopharynx

false

T/F

flow of lacrimal secretion

lacrimal gland → lacrimal ducts → ocular surface → lacrimal lake → lacrimal canaliculi → lacrimal sac → nasolacrimal duct → inferior nasal meatus → nasopharynx

false

T/F

flow of lacrimal secretion

lacrimal gland → lacrimal ducts → ocular surface → lacrimal puncta → lacrimal papilla → lacrimal sac → nasolacrimal duct → inferior nasal meatus → nasopharynx

orbit

bilateral bony cavities in facial skeleton

orbit

hollow, quadrangular pyramidal cavity

anterolaterally

direction of orbit base

posteromedially

direction of orbit apex

orbit

medial walls of 2 orbits, separated by ethmoidal sinuses and upper parts of nasal cavity are nearly parallel

orbit

lateral walls approx 90 degrees angle

optical axes

axes of gaze; axis at which actual eyeballs are directed, parallel, looking straight ahead

orbital axis

axis at which orbits of eye are directed, divergent about 45 degrees

superior or roof boundary of orbit

orbital part of frontal bone

superior or roof boundary of orbit

lesser wing of sphenoid

superior or roof boundary of orbit

fossa of lacrimal gland

lateral boundary of orbit

process of frontal and zygomatic bones

lateral boundary of orbit

greater wing of sphenoid

inferior or floor boundary of orbit

maxilla and partly by zygomatic and palatine bones

medial boundary of orbit

orbital plate of ethmoid bone

medial boundary of orbit

frontal recess of maxilla, lacrimal, and sphenoid bones

apex boundary of orbit

optic canal in lesser sphenoid wing

apex boundary of orbit

medial to superior orbital fissure

base boundary of orbit

orbital margin and orbital opening

inferior or floor boundary of orbit

only wall of orbit without spenoid bone, contains nasolacrimal duct

inferior or floor boundary of orbit

most fractured wall of orbit

medial boundary of orbit

thinnest wall of orbit, has lamina papyracea or orbital lamina of ethmoid bone

lateral boundary of orbit

strongest and thickest wall of orbit

orbital opening

lies anteriorly, 1/6th of eyeball is exposed through this opening

supraorbital notch

situated on superior orbital margin, transmits supraorbital nerve and vessels

infraorbital groove and canal

on floor of orbit in orbital plate of maxilla, transmits infraorbital nerve

nasolacrimal canal

formed by maxilla, lacrimal, and inferior concha, communicates with inferior meatus of nose

nasolacrimal canal

transmits nasolacrimal duct from lacrimal sac to inferior nasal meatus

inferior orbital fissure

posteriorly between maxilla and greater wing of sphenoid

inferior orbital fissure

communicates with infratemporal impetigo pterygopalatine fossa

inferior orbital fissure

transmits maxillary nerve, inferior ophthalmic vein, sympathetic nerves

superior orbital fissure

posteriorly between greater and lesser wings of sphenoid, communicates with middle cranial fossa

superior orbital fissure

transmits lacrimal nerve, frontal nerve, trochlear nerve, oculomotor nerve, superior ophthalmic vein

optic canal

connects orbit with middle cranial fossa

optic canal

posteriorly in lesser wing of sphenoid and communicates with middle cranial fossa

eyelids

control exposure of anterior eyeball