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BDS3 ANATOMY > 26 - Eye and Orbit > Flashcards

26 - Eye and Orbit Flashcards

1
Q

What bones make up the margin of the orbit?

A
  • frontal
  • maxilla
  • zygomatic
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2
Q

What bones make up the walls of the orbit?

A
  • frontal
  • maxilla
  • zygomatic
  • lacrimal
  • ethmoid
  • sphenoid
  • palatine (minor)
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3
Q

What are the main openings into the orbit?

A
  • superior orbital fissure
  • inferior orbital fissure
  • nasolacrimal canal
  • optic canal
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4
Q

What structures pass through the inferior orbital fissure?

A

Inferior ophthalmic vein

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5
Q

What structures pass through the superior orbital fissure?

A
  • trochlear nerve
  • abducent nerve
  • opthalmic nerve branches (CNV1)
  • occulomotor nerve
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6
Q

What structures pass through the optic canal?

A
  • optic nerve
  • opthalmic artery
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7
Q

What structures pass through the nasolacrimal canal?

A

Nasolacrimal duct

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8
Q

Which branches of CN V1 pass through the superior orbital fissure?

A
  • frontal
  • lacrimal
  • nasocillary
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9
Q

Which branches of CN III pass through the superior orbital fissure?

A
  • superior
  • inferior
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10
Q

Describe the structure of the optic nerve.

A
  • surrounded by cranial meninges
  • contains central retinal artery and vein
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11
Q

What are the contents of the orbit?

A
  • eyeball
  • retrobulbar fat
  • optic nerve
  • extraocular muscles
  • eyelids and lacrimal apparatus
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12
Q

Describe how the optic nerve enters the skull.

A
  • leave the brain as the two optic tracts
  • meet at the optic chiasm as they enter the skull
  • enter the skull as the two optic nerves
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13
Q

What is papilloedema?

A
  • raised intracranial pressure is transmitted to the meninges surrounding the eye
  • venous drainage of the eye slows
  • causes swelling of the optic disc
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14
Q

What is amaurosis fugax?

A
  • when the central retinal artery becomes occluded
  • painless and temporary loss of vision
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15
Q

Describe how injury to the optic nerve affects the visual field.

A
  • vision is lost completely in one eye
  • nerve from both sides of the brain are damaged
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16
Q

Describe how injury to the optic chiasm affects the visual field.

A
  • tunnel vision
  • lateral vision is lost as the nerves from both sides cross over
17
Q

Describe how injury to the optic tract affects the visual field.

A
  • field of vision on the contralateral side is lost
  • injury before the tract crosses over
18
Q

Where is the lacrimal gland located?

A

Upper lateral corner of orbit

19
Q

Describe the drainage of the lacrimal gland.

A
  • tears released in the upper lateral corner of the eye
  • washed over the eye by the orbicularis oculi
  • form a lake in the medial corner of the eye (lacrimal caruncle)
  • drain via puncta to the lacrimal sac and then to the nasolacrimal duct
  • drains into inferior nasal meatus
20
Q

Describe the parasympathetic innervation of the lacrimal gland.

A
  • preganglionic fibres from nervus intermedius (CN VII)
  • travel in greater petrosal nerve, then nerve of pterygoid canal
  • arrive at the pterygopalatine ganglion
  • postganglionic fibres via zygomatic branch (CN V2) to lacrimal gland
21
Q

What are the extraocular muscles?

A
  • superior oblique
  • inferior oblique
  • medial rectus
  • lateral rectus
  • superior rectus
  • inferior rectus
  • levator palpebrae superioris
22
Q

Describe the origin and insertion of the extraocular muscles.

A
  • all originate from the common tendinous ring at the posterior of the orbit
  • EXCEPT the inferior oblique which originates from the maxilla
  • all insert to the sclera
23
Q

What muscle pulls the eye medially?

A

Medial rectus

24
Q

What muscle pulls the eye medial and superiorly?

A

Superior rectus

25
Q

What muscle pulls the eye laterally?

A

Lateral rectus

26
Q

What muscle pulls the eye lateral and superiorly?

A

Inferior oblique

27
Q

What muscle pulls the eye inferiorly?

A

Inferior rectus and superior oblique

28
Q

What muscle pulls the eye superiorly?

A

Superior rectus and inferior oblique

29
Q

What muscle pulls the eye laterally and inferiorly?

A

Superior oblique

30
Q

What muscle pulls the eye medially and inferiorly?

A

Inferior rectus

31
Q

Describe the innervation of the extraocular muscles.

A
  • LR6 SO4 AO3
  • lateral rectus = abducent
  • superior oblique = trochlear
  • all others = occlumotor
32
Q

Describe the oculomotor nerve.

A
  • supplies extraocular muscles
  • supplies parasympathetic fibres for pupillary construction
  • supplies sympathetic fibres to the smooth muscle fibres in levator palpebrae superioris
33
Q

How does injury to the oculomotor nerve present?

A
  • mydriasis (dilated pupil) by loss of parasympathetic constriction
  • ptosis (drooping eyelid) by loss of function of levator palpebrae superioris
  • eye turned downwards and outwards (unopposed SO and LR muscles still acting)
34
Q

What are the outer layers of the eyeball?

A
  • sclera (replaced anteriorly by the cornea)
  • choroid (vascular)
  • retina
35
Q

Describe the structure of the eyeball.

A
  • cornea outermost layer
  • anterior and posterior chamber are separated by the iris
  • the chambers communicate via the pupil
  • chambers contain aqueous humour
  • lens innermost
  • vitreous chamber makes up bulk of eye, filled with vitreous humour
36
Q

Describe where the visual and non visual parts of the retina are located.

A
  • visual parts on medial, lateral and posterior walls
  • non visual part on anterior wall
37
Q

What is aqueous humour?

A
  • secreted by ciliary body in the choroid layer of the eyeball
  • reabsorbed by the scleral venous sinus
38
Q

What is glaucoma?

A
  • excess pressure due to aqueous humour
  • can be treated using drugs that constrict the pupil and pull the sinus open
39
Q

What are the muscles found in the anterior eye and how are they controlled?

A
  • ciliaris (in ciliary body, parasympathetic)
  • dilator pupillae (sympathetic)
  • sphincter pupillae (parasympathetic)
  • all innervated by CN III

BDS3 ANATOMY (27 decks)

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