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What cranial nerve innervates the forehead muscles?
Name the forhead muscles
- Obicularis Oculi
Which muscle is the main elevator of the eyebrows?
Which muscles are the medial depressors of the eyebrows?
Corrugator and Procerus
Which muscle is the lateral depressor of the eyebrows?
4 main functions of the eyelids
- Cover the globe for protection.
- Move the tears toward drainage at the medial canthus on closure.
- Spread the tears film over the anterior surface of the eye on opening.
- Contain structures that produce tear film.
What is the palpebral fissure?
The Area between the open eyelids
Where is the mormal position of the upper and lower lids?
- The upper lid covers the superior limbus
- The lower lid is usually lying 1 mm of the inferior limbus (variable)
- The Upper and Lower eyelids meet at the corners of the palpebral fissure in the lateral and medial canthus
Where is the lateral canthus located
Approx 5-7 mm medial to the bony orbital margin and lies directly on the globe
Where is the medial canthus located
Is a medial orbital margin but is separated from the globe by a reservour for the pooling of tears, the lacrimal lake.
What is the lacrimal lake?
A reservoir for the pooling of tears
What is the pilca semulinaris and what is its function?
Is a narrow crescent- shaped fold of the conjunctiva. It allows lateral movement of the eye.
What is the caruncle?
A Small pink mass of modified skin just medial to the pilca.
What normally composees the caruncle?
Is covered with epithelium, contains goblet cells and fine hairs, and sweat glands
How are the tarsal and orbital portions divided?
The superior palpebral sulcus
How is the superior palpebral sulcus made?
Fibers of the superior palpebral levator muscle pass through the fibers of orbicularis oculi and get inserted into the skin.
What eyelid portion rests against the globe?
The tarsal portion of the lower lid
Where are the meibomian glands and eyelashes located?
They rest along the globe, and the eyelashes are arranged at the lid margin in a double and triple row.
Approximately how are many lashes are in the upper and lower eyelid margins?
- 150 in upper lid
- 75 in lower lid
What is the name of the transition from skin to conjunctiva in the eyelid margin?
Where is the gray line of the eyelid margin located?
Runs between the cilia insertions and the poors of the meibomian glands.
In how many portions is the eyelid margin divided and what are the names of each one?
- Lacrimal portion= The medial 1/6 th
- Ciliary portion = The laterat 5/6ths
What structure divides the portions of the eyelid margins?
The lacrimal papilla
What is the lacrimal papilla?
Small elevation containing the lacrimal punctum
Name the first layer of the eyelids
The Skin layer
What composes the structres of the skin layer of the eyelids?
Contains fine hairs, sweat, and subaceous glands
What is the most important characteristic of the skin layer of the eyelids?
It is the thinnest layer of skin in the body and contains no fat.
What connective tissue layer lies between the skin layer and the orbicularis layer?
Subaceous areolar layer
Mention the 2 portions of the orbicularis oculi.
The orbital portion and the palpebral portion. The palpebral portion controls facial expression by CN VII.
What portion of the orbicularis oculi muscle is used for forced closure of the eyelids?
The orbital portion
What type of blinking uses the palpebral portion of the orbicularis muscle?
Spontaneous and reflex blinking
Where is the muscle of Riolan located
The most superficial poetion of the Palpebral portion
What is the function of the muscle of Riolan
It keeps the lid margin tightly applied to the globe during eye movements, and may contribute to rotating the eyelashes toward the eye during eye closure.
What is the function of the muscle of Horner?
Drais tears into the lacrimal sac.
What is the function of the orbital septum?
It serves as a barrier which restricts fat from falling down onto the lid margins. It also keeps infections localized to the anterior portion of the eyelid, away from the orbit.
Where is the tarsal plate located in the orbicularis?
Behind the palpebral portion of the orbicularis
What is the other name of the tarsal muscle?
The Muller muscle
Where does the superior palpebral muscle originate
The lesser wing of the sphenoid
Which muscle is the main retractor of the upper eyelid (15mm)?
Superior palpebral levator muscle
What is the function of the Whitnall's ligament of the superior palpebral elevator?
Serves as a fulcrum and changes the course of the muscle from anterior-posterior direction to superior-inferior.
Through which muscle does the levator aponeurosis pass and attach to the skin and the superior surface of the tarsal plate?
Superior palpebral of orbicularis
What type of muscle is the tarsal (Muller) muscle?
Where does the tarsal muscle originate?
The levator and extends into the tarsal plate
Which muscle is the minor retractor of the upper eyelid (2-3 mm)?
The tarsal (Muller) muscle- It provides the upper eyelid lift by widening the palpebral fissure.
What glands are surrounded by the tarsal plate?
The meibomian glands (subaceous glands)
What is the name and function of the palebral ligaments?
- The medial and lateral palpebral ligaments
- Bands of dense connective tissue connecting the tarsal plates to the orbital rim and holding the tarsal plates in position.
What palpebral ligament is divided into two limbs and where are they attached?
The medial palpebral ligament- one attached to anterior lacrimal crest, other to the posterior lacrimal crest.
Where does the lateral palpebral ligament attach?
To the lateral edges of the trasal plates to the lateral orbit margin -occurs at the lateral orbital tubercle.
Which are the two layers of the palpebral conjunctiva (inner and outer)?
- Inner= Submucosa
- Outer= Stratisfied epithelial layer
In which layers of the conjunctiva are the goblet cells located?
The stratisfied epithelial layer
What do the goblet cells produce
Innermost mucous layer of the tear film
What are the Crypts of Henle?
Invaginations of conjunctivial epithelium
Which are the two layers of the submucosa (conjunctiva)?
The outer lymphoid layer and the Deep fibrous layer
Of what is composed of the lymphoid layer of the conjunctiva'?
IgA, Macrophages, Mast cells, PMN's and eosinophils
What is the fibrous layer of the conjunctiva composed of?
Accessory lacrimal glans, nerves, and blood vessels.
Name the five types of glands you can find in the eyelids.
- Meibomian Glands
- Glands of Zeis
- Glands of Moll
- Glands of Krause
- Glands of Wolfrig
Which glands are the sebaceous glands?
Meibomian glands and Glands of Zeiss
Where do the meibomian glands drain?
They drain into the opening duct located at the eyelid margin
Which sebaceous glands are located near the eyelash follicles to lubricate them?
Glands of Zeiss
Which glands are modified sweat glands?
Glands of Moll
Name the two accessory lacrimal glands and where they are located.
- Glands of Krause- located in the fornices
- Glands of Wolfrig- predominate near the tarsal conjunctiva
What nerve provides sensory innervation to the eyelids?
The trigeminal nerve
Name the branches of the opthalmic division of the trigeminal nerve that provide sensory innervation to the upper eyelid.
Opthalmic- Supraorbital, Supratrochlear, Infratrochlear, and Lacrimal nerves
What nerves provide sensory innervation to the lower eyelids?
Infratrochlear (part of ophthalmic) and Infraorbital (maxillary)
What nerves supply motor innervation to the orbicularis muscle?
The voluntary motor- The temporal and zygomatic branch of the facial nerve.
What nerves provide involuntary motor innervation to the tarsal muscles?
The sympathetic nerves
What arteries anastomose to supply blood to the eyelids by the peripheral arcades?
The medial palpebral artery (superior and inferior) and the Lateral Palpebral Artery.
Name the two branches of the opthamic artery that supplies blood to the eyelids?
Mariginal and peripheral
Name the three types of eyelid blinking
Spontaneous, Reflex, Forced
What muscle is in charge of the spontaneous blinking?
The palpebral portion of the orbicularis oculi
What is the normal spontaneous blink rate?
15 per min
What types of stimuli can produce reflex blinking?
- Auditory, Touch or irritation (CN7)
- Dazzle, Menace (CN2)
What portions of the orbicularis muscle are contracted during a forced blink?
Both palpebral and orbital
What is the Bell's Phenomenon?
The up and outward rotation of the globe when the globe is retracted during a blink.
Name the three tear proceses in which the eyelids have a role
Distribution, Production, and Drainage
What muscles can be affected by CN VII palsy?
The Orbicularis oculi
What is the function of the conjunctiva?
It ensures smooth movement of the eyelids over the globe
Name the three main divisions of the conjunctiva and its locations.
- Palpebral/tarsal conjunctiva- tissue lining the eyelids
- Bulbular conjunctiva- tissue covers the sclera
- Conjunctival Fornix (cul-de-sac) connected palpebral and bulbar sections
Which layer of the bulbar conjunctiva is vascularized?
The submucosa (stroma)
What does the pilca semilunaris contain?
Smooth muscle, Goblet cells, Adipose tissue
What is the function of the pilca semilunaris?
Reduces stretching of conjunctiva on lateral movements
What arteries supply blood to the bulbar conjunctiva
The anterior ciliary arteries
What arteries supply blood to the palpebral and forniceal portions of the conjunctiva?
The peripheral arcades (upper and lower lids)
Branches of what nerve give sensory innervation to the conjunctiva?
Long posterior ciliary nerves
What portion of the conjunctiva receives sensory innervation by the long porterior ciliary nerves?
The Bulbar conjunctiva
What nerves provide sensory innervation to the palpebral conjunctiva?
- Superior- frontal and lacrimal branches of the opthalmic nerve.
- Inferior- lacrimal nerve and the infraorbital branch of the maxillary nerve.
The lacrimal system (or Apparatus) is composed of:
- The lacrimal gland
- The lacrimal canaliuli
- The lacrimal sac
- The nasolacrimal duct
- a= lacrimal gland
- b= Superior lacrimal punctum
- c= Superopr lacrimal cana
- d= lacrimal sac
- e= inferior lacrimal punctum
- f= inferopr lacrimal canal
- g= nasolacrimal canal
What are the lacrimal canaliculi ( lacrimal canals or lacrimal ducts)
Small channels in each eyelid that commence at minute orifices, termed puncta lacrimalia, on the summits of the papillae lacrimales, seen on the margins of the lids at the lateral extremity of the lacus lacrimalis.
How does the superior duct (the shorter of the two) run
It first ascends, and then bends at an acute angle, and passes medialward and downward to the lacrimal sac.
How does the inferior duct run
It first descends, and then runs almost horizontally to the lacrimal sac
At angles, the lacrimal canaliculi is dilated into what, and is lined by what?
Is dilated into ampullae. Seen under a microscope they are lined by nonkeratinizing stratified squamous epithelium surrounded by fibrous tissue.
What are the layers of the lacrimal canaliculi
The outside layer is a layer of striped muscle, continuous with the lacrimal part of the Orbicularis oculi; at the base of each lacrimal papilla, the muscular fibers are circularly arranged and form a kind of sphincter.
The lacrimal sac
- The lacrimal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla
- It connects the lacrimal canaliculi, which drain tears from the eye's surface, and the nasolacrimal duct, which conveys this fluid into the nasal cavity.
- This is mainly for high amounts of tears, in which the lacrimal sac pumps inward and outward driven by the orbicularis muscle during blinking.
- It is oval in form and measures from 12 to 15 mm. in length; its upper end is closed and rounded; its lower is continued into the nasolacrimal duct
- Its superficial surface is covered by a fibrous expansion derived from the medial palpebral ligament, and its deep surface is crossed by the lacrimal part of the Orbicularis oculi, which is attached to the crest on the lacrimal bone.
What is the lacrimal sac lined with
by stratified columnar epithelium with mucus-secreting goblet cells, with surrounding connective tissue. The Lacrimal Sac also drains the eye of any debris, bacteria, dirt, etc.
Nasal lacrimal duct info:
- (sometimes called the tear duct) carries tears from the lacrimal sac into the nasal cavity.
- The opening of the nasolacrimal duct into the inferior nasal meatus is partially covered by a mucosal fold (valve of Hasner or plica lacrimalis)
- The duct is lined by stratified columnar epithelium containing mucus-secreting goblet cells
- Obstruction of the nasolacrimal duct, known as dacryostenosis
- Leads to the excess overflow of tears called epiphora
- A congenital obstruction can cause cystic expansion of the duct and is called a dacrocystocele or Timo cyst
- Persons with dry eye conditions can be fitted with punctal plugs that seal the ducts to limit the amount of fluid drainage and retain moisture.
Lacrimal gland- more info
- -The lacrimal glands are paired almond-shaped glands
- -Situated in the upper, outer portion of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone
- -Inflammation of the lacrimal glands is called dacryoadenitis
- -Anatomists divide the lacrimal gland into two sections:
- The Palpebral portion
- The Orbital portion
- It is a compound tubuloacinar gland, made up of many lobules separated by connective tissue, each lobule contains many acini.
- The acini contain only serous cells and produce a watery serous secretion.
- Each acinus consists of a grape-like mass of lacrimal gland cells with their apices pointed to a central lumen
- The central lumen of many of the units converge to form intralobular ducts, and then unite to from interlobular ducts.
- The lacrimal artery, derived from the ophthalmic artery supplies the lacrimal gland.
- Venous blood returns via the superior opthalmic vein
The lacrimal nerve, derived from the opthalmic nerve supplies the lacrimal gland
Innervation is sensoral and autonomic
- •SENSORIAL IS GIVEN BY THE LACRIMAL NERVE
- •AUTONOMIC INNERVATION:
- •THE LACRIMAL GLAND RECEIVES BOTH SYMPATHETIC AND PARA SYMPATHETIC INNERVATION
- •THE SYMPATHTIC INNERVATION COMES FROM THE SUPERIOR CERVICAL GANGLION AND THE PARASYMPATHETIC INNERVATION FROM THE SUPERIOR SALIVATORY NUCLEUS
- •BOTH HAVE SECRETOMOTOR ACTION UPON THE GLAND TISSUE
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