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Flashcards in Anatomy of the Eye Deck (36):
0

Which bones make up the floor of the orbit?

Maxilla and zygomatic

1

Which bones make up the medial surface of the orbit?

Ethmoid, lacrimal and maxilla

2

Which bones make up the lateral surface of the orbit?

Zygomatic and sphenoid

3

Which structures pass through the supra-orbital fissure of the orbit?

Sympathetic nerves
Ophthalmic veins
Frontal nerve
Trochlear nerve (CN4)

Superior branch of the oculomotor nerve (CN3)
Nasociliary nerve
Inferior branch of the oculomotor nerve (CN3)
Abducens nerve (CN6)
Lacrimal nerve

4

What are the coverings of the optic nerve?
What is the importance of this?

It has coverings of pia, arachnoid, and dura mater of the meninges so infections can spread from the eye to the brain

5

What is meant by the lacrimal apparatus?

Lacrimal glands, ducts and canaliculi

6

How do the lacrimal secretions drain in to the nasal cavity?

Superior and inferior puncta, superior and inferior canaliculi, through the lacrimal duct, lacrimal sac, passes through the nasolacrimal duct, which opens into the inferior meatus

7

What are the seven extra-ocular muscles?

Levator palpebrae superioris
Superior, inferior, medial and lateral recti
Superior and inferior obliques

8

Where do the recti muscles arise from?
What is the importance of this structure?

A fibrous cuff = the common tendinous ring
It surrounds the optic canal and attaches to the sclerae on the anterior half of the eyeball

9

What does the superior rectus muscle do?
How is it innervated?

Moves the eye superiorly to look up
CN3 oculomotor nerve

10

What does the inferior rectus muscle do?
How is it innervated?

Moves the eye inferiorly to look down
CN3 - oculomotor nerve

11

What does the lateral rectus muscle do?
How is it innervated?

Moves the eye laterally
CN6 - abducens nerve

12

What does the medial rectus muscle do?
How is it innervated?

Moves the eye medially
CN3 - oculomotor nerve

13

What does the superior oblique muscle do?
How is it innervated?

Internal rotation, depressed in adducted position, abduction
CN4 - trochlear nerve

14

What does the inferior oblique muscle do?
How is it innervated?

Lateral rotation and adduction
CN3 - oculomotor
It doesn't arise from the annulus

15

What is meant by the optical axis?

The axis where the eyes point forward

16

What is meant by the orbital axis?

Halfway between the medial and lateral walls of the orbit

17

What vessels are found within the optic nerve?

Central artery and vein

18

In a fundoscopy, what can we see if there is an increase in ICP?

Venous engorgement and papilloedema (optic disc swelling)

19

What muscles are responsible for the opening of the eyelid?

Levator palpebrae superioris
And the superior tarsal muscle

20

What muscles are responsible for the closing of the eyelid?

Orbicularis oculus

21

What nerves produce the corneal (blink) reflex?

CN V1 (sensory)
CN VII (motor)

22

What is the venous drainage of the orbit?

Superior and inferior ophthalmic veins, which drain in to the cavernous sinus

23

What is meant by the danger space?

Communication between facial vein to cavernous sinus via ophthalmic veins
Cavernous sinus thrombosis, meningitis, brain abscess
The facial vein has no valves so blood may pass in the opposite direction and may enter the cavernous sinus

24

What happens in an abducens nerve palsy?

Loss of innervation to the lateral rectus, unable to abduct the eye, eye is fully adducted due to the unopposed pull of the medial rectus
Caused by fractures involving the orbit of cavernous sinus

25

What happens in a trochlear nerve palsy?

Loss of innervation to the superior oblique
Unable to look down when the eye is adducted
Caused by orbital fractures or stretching of the nerve during its course around the brainstem

26

What happens in an oculomotor nerve palsy?

Loss of innervation to all extra-ocular muscles expect so and lr
Eye is down and out due to opposed action of so and lr
Ptosis - loss of lps, unopposed action of orbicularis oculi
Pupil is fully dilated and un reactive - loss of sphincter pupillae and unopposed action of dilator pupillae
Caused by fractures involving the cavernous sinus or aneurysms

27

During examination of the eye, which side of the fundus would you find the "blind spot" in a normal eye?

It lies on the nasal side of the fundus

28

Why might a lesion of the ophthalmic division of the trigeminal nerve be dangerous to the eye?

It supplies the sensory component to the cornea, the cornea becomes insensitive to touch and specks of dust or grit will not be felt in the eye. This quickly leads to corneal ulceration and scarring

29

What is the arterial supply to the orbit?

Internal carotid artery gives rise to the central artery to the retina and the ophthalmic artery via the optic canal (lacrimal artery, muscular branches, posterior ciliary arteries)
Also, minor source: intra-orbital artery off the maxillary artery off the external carotid

30

What happens if there is paralysis of levator palpebrae superioris?

Ptosis - compromising vision
Residual opening - due to the superior tarsal muscle

31

What happens if there is paralysis of orbicularis oculi?

Loss of blink and corneal reflex
Dry eyes and a risk of infection
Damage to the muscle causes the eyelid to fall away from the eye

32

What is meant by a blow-out fracture?
What are some of the consequences?

Fracture of medial or inferior walls of the orbit
The ethmoid, sphenoid and maxillary sinuses can become full of flood
The contents of the sinuses can spread, causing infection
Muscles in the inferior part of the orbit can become trapped, diplopia

33

What is meant by enopthalmos?

The eye sits further back than usual (this mp an be due to the impact of an force)

34

What is meant by ptosis?

Dropping of the upper eyelid

35

Which bones make up the roof of the orbit?

Frontal and sphenoid