Eyelid and lacrimal apparatus Flashcards
The eyelids are split into upper and lower portions and they meet at
medial and lateral canthi of eye
Opening between the two eyelids are called
palpebral aperture
Function of palpebral aperture
Offer protection from excessive light
maintain lubrication by distributing tears over the surface of the eyeball
5 layers of the eyelid
skin and subcutaneous tissue
orbicularis oculi
tarsal plates
levator apparatus
conjunctiva
The eyelids are attached at the first layer with their modified sweat glands called
ciliary glands of moll
Sebaceous glands located in the first layer are
gland of zeis
Describe the first layer
Thinnest part in the human body
presence of subcutaneous tissue but no subcutaneous fat and as a result eyelid is readily distended with oedema or blood
Parts of orbicularis oculi
orbicularis part
palpebral part
lacrimal part
Origin of orbicularis oculi
medial orbital margin, medial palpebral ligament and lacrimal bone
Insertion of orbicularis oculi
inserts into skin around margin of orbit and the sup and inf tarsal plates
Action of orbicularis oculi
orbital part- tightly closes eyelids
palpebral part- gently closes eyelids
lacrimal part- drainage of tears
Innervation of orbicularis oculi
zygomatic and temporal branch of facial nerve
location of tarsal plates
deep to palpebral part of orbicularis oculi
types of tarsal plates
sup tarsus- upper eyelid
inf tarsus- lower eyelid
Function of tarsal plates
form scaffolding of the eyelids
Tarsal plates are composed of
dense CT
What glands are located in the tarsal plates
Meibomian or tarsal glands
Superior tarsus serves as attachment for
levator palpebrae superioris
What are meibomian glands
They are a specialized type of sebaceous glands that secrete an oily substance.
The oily substance prevents the eyelids from sticking together when closed
Where is the levator apparatus located
Upper eyelid
Levator apparatus is made up of
levator palpebrae superioris
superior tarsal muscle
Action of levator palpebrae superioris
Opens eyelid
Innervation of levator palpebrae superioris
sup branch of oculomotor nerve
Origin and insertion of levator palpebrae superioris
Originates from lesser wing of sphenoid and inserts into the upper eyelid and sup tarsal plate
Origin of sup tarsal muscle
underside of LPS
insertion of sup tarsal muscle
sup tarsal plate
Innervation of sup tarsal muscle
sympathetic fibers from sup cervical ganglion
Action of sup tarsal muscle
Assists LPS in opening eyelids
Conjunctive is reflected unto sclera of eyeball as
bulbar conjunctiva
Venous drainage of eyelid
med-medial palpebral vein drain into opthalmic vein and angular vein
lat- lateral palpebral vein drains into sup temporal vein
Arterial supply of eyelid
Opthalmic artery and its branches- lacrimal, medial palpebral, supraorbital, dorsal nasal, supratrochlear.
angular branch of facial artery
Transverse facial branch of
superficial temp artery
Innervation to eyelids
opthalmic nerve branches to upper eyelid- supraorbital, supratrochlear,infratrochlear and lacrimal
Maxillery nerve branches to lower eyelid- infraorbital and zygomaticofacial
CLINICAL CORRLEATES OF EYELID
Stye- infection of hair follicle(external stye) or meibomian glands (internal stye) around the eyelash
What is a chalazion
painless granuloma of the meibomian glands
distinguished from stye by absence of pain
Lacrimal glands produce what when in excess
Tears
Lacrimal lake is found in
med canthi of eye
Describe the lacrimal glands
They are serous type exocrine glands that secrete lacrimal fluid unto the surface of the conjunctiva and cornea of the eye
Lacrimal gland is divided into
orbital part- larger and sits on lat margin of LPS
palpebral part- smaller and in inner surface of eyelid
Lacrimal fluid produced by the excretory ducts of lacrimal glands empty into
sup conjunctival fornix
What is the dilated end of the nasolacrimal duct
lacrimal sac
Location of lacrimal gland
anteriorly in the superolateral aspect of the orbit within the lacrimal fossa
Relation of lacrimal gland
sup- zygomatic process of frontal bone.
Ant- orbital septum
Post- orbital fat
Inferolateral-lateral rectus
lacrimal fluid drains down nasolacrimal duct empties into
into inf meatus
After secretion, lacrimal fluid circulates around the eye and accumulates in the
lacrimal lake
Describe the lacrimal apparatus
system responsible for draining lacrimal fluid from orbit
From the lacrimal lake, the lacrimal fluids drain into
Lacrimal sac via series of canals
Blood supply of lacrimal gland
Art supply-Lacrimal branch of ophthalmic artery
Venous drainage- sup ophthalmic vein which drains into cavernous sinus
Lymphatic drainage of lacrimal gland
superficial parotid lymph nodes- empties into sup deep cervical lymph nodes
Innervation of lacrimal gland
lacrimal branch of opthalmic nerve
parasympathetic fibers stimulate fluid secretion from lacrimal gland
sympathetic fibers inhibit fluid secretion from lacrimal gland
inf rectus
originates from inf aspect of common tendinous ring
inserts into inf and ant aspect of sclera
depresses eyeball.
contributes to adduction and lat rotation of eyeball
Oculomotor nerve
sup rectus muscle
originates from sup aspect common tendinous ring
attaches to sup and ant aspect of sclera
elevates eyeball.
contributes to adduction and med rotation of eyeball.
Oculomotor nerve
med rectus
Originates from common tendinous ring
inserts into anteromedial aspect of the sclera
adducts eyeball
oculomotor nerve
inf oblique muscle
originates from ant aspect of orbital floor
inserts into sclera of eye post to lat rectus
elevates, abducts and lat rotates eyeball
oculomotor nerve
sup oblique muscle
originates from body of sphenoid
inserts into the sclera post to sup rectus
depresses, abducts and medially rotates eyeball
trochlear nerve
lat rectus
originates from lat aspect of common tendinous ring
inserts into anterolateral aspect of the sclera
abducts eyeball
abducens nerve
