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Ophthalmology > Anatomy: orbital cavity, eyelids, lacrimal apparatus, conjunctiva > Flashcards

Anatomy: orbital cavity, eyelids, lacrimal apparatus, conjunctiva Flashcards

1
Q

What shape is the orbital cavity?

A

Pyramidal

Apex points posteriorly and base anteriorly

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2
Q

What bones of the skull make the roof of the orbital cavity?

A

Frontal and lesser wing of sphenoid

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3
Q

What bones of the skull make up the floor of the orbit?

A

Maxilla, palatine and zygomatic

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4
Q

What bones make up the medial wall of the orbit?

A

Ethmoid, maxilla, lacrimal, sphenoid

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5
Q

What bones of the skull make up the lateral wall of the orbit?

A

Zygomatic, greater wing of sphenoid

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6
Q

What are the 3 openings at the apex of the orbit called?

A

Superior orbital fissure
Inferior orbital fissure
Optic canal

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7
Q

What paranasal air sinus is below the orbit?

A

Maxillary

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8
Q

What paranasal air sinus is medial to the orbit?

A

Ethmoid

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9
Q

Which parts of the orbital cavity are weakest?

A

Medial wall and floor (due to the air filled cavities)

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10
Q

What is another term for eyelids?

A

Palpebrae

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11
Q

What is the function of the eyelids?

A

Protect the eye when palpebral fissure closed

Keep cornea moist by covering it in a tear film

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12
Q

The inner surface of the eyelid is lined by what?

A

Palpebral conjunctiva - this reflects on the eyeball and is continuous with the bulbar conjunctiva (overlays the anterior surface of eye)

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13
Q

Movement of the eyelids occurs via what 2 muscles?

A

Obicularis occuli and levator palpebrae superioris

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14
Q

What is LPS innervated by?

A

Occulomotor nerve

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15
Q

What innervates obicularis occuli?

A

Facial nerve

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16
Q

What makes up the fibrous skeleton of the eyelids?

A

Tarsal plates

17
Q

What glands do the tarsal plates contain?

A

Meibomian glands - modified sebaceous gland secreting lipid

18
Q

What are the contents of the orbital cavity?

A 
Lacrimal apparatus 
Nerves and blood vessels 
Orbital fat 
Globe of eye 
Extra ocular muscles
19
Q

What is the orbital septum?

A

Thin sheet of fibrous tissue originating from orbital rim that separates intra orbital contents from eyelid fat and obicularis oculi

20
Q

Why is the orbital septum useful?

A

Prevents infection spreading from pre septal space to post septal space

21
Q

Meibomian glands open at the lid margin. Two other types of glands also open here, what are they called?

A

Glands of Moll

Glands of Zeiss

22
Q

What type of glands are glands of Moll?

A

Modified sweat glands

23
Q

What type of glands are glands of Zeiss?

A

Sebaceous glands

24
Q

Obstruction to the tarsal glands can lead to a painless swelling of the eyelid called…

A

A chalazion

25
Q

What is a stye?

A

An acute infection of a gland of Moll, Zeiss or the eyelash follicle

26
Q

What is another name for a stye?

A

Hordeolum externum

27
Q

What comprises the lacrimal apparatus?

A

Lacrimal glands, lacrimal ducts, lacrimal canaliculi

28
Q

Where is the lacrimal gland located?

A

In a fossa on the upper lateral part of the orbit

29
Q

Describe the route of the lacrimal fluid

A

From the lacrimal gland through the lacrimal ducts and into the conjunctival sac -> into lacrimal lake at medial angle of eye -> drains into lacrimal sac via lacrimal canaliculi then down the nasolacrimal duct

30
Q

Where does the nasolacrimal duct open into?

A

Nasal cavity - inferior meatus

It is then swallowed

31
Q

Is there any anastomotic pathways for the drainage of tears?

A

No - an obstruction will cause overflow

32
Q

What is tear overflow called?

A

Epiphora

33
Q

What is the conjunctiva and what does it cover?

A

A transparent mucous membrane that produces mucus and tears

Covers the white of the eye (sclera) and lines the inside of the eyelids (forming a conjunctival sac)

34
Q

Does the conjunctiva cover the cornea?

A

No

35
Q

Is the conjunctiva vascular ?

A

Yes

36
Q

What is the role of blinking?

A

Washes tear film across front of eye - rinsing and lubricating conjunctiva and cornea

37
Q

Why are tears needed?

A

Provide smooth surface
Allows light rays to be refracted uniformly
Lubrication to prevent friction
Antibacterial properties

38
Q

What are the 3 components of the tear film?

A

Surface lipid layer - from Meibomian glands
Middle aqueous layer - from lacrimal gland
Inner mucus layer - from goblet cells of conjunctiva and epithelial cell surface

39
Q

Tears are rich in protein especially…

A

IgA

Ophthalmology (25 decks)

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