Orbit 2 Flashcards

1
Q

Name 2 sensory nerves to the eyeball

A
  1. Optic

2. Ophthalmic of trigeminal

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2
Q

Name 3 sensory nerves to the eyeball

A
  1. Oculomotor
  2. Trochlear
  3. Abducent
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3
Q

What are the 3 branches of the ophthalmic nerve?

A
  1. Frontal
  2. Lacrimal
  3. Nasociliary
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4
Q

What are the 2 terminal branches of the frontal nerve?

A
  1. Supratrochlear

2. Supraorbital

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5
Q

Where do the supratrochlear and supraorbital nerves innervate?

A

Sensory innervation for skin of forehead and scalp

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6
Q

Where does the lacrimal nerve innervate?

A

Lacrimal gland

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7
Q

Once innervating the lacrimal gland, what happens to the lacrimal nerve?

A

Pierces orbital septum and supplies the skin of lateral part of the eyelid

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8
Q

Where does the nasociliary nerve innervate?

A

Anterior nasal mucosa

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9
Q

Describe the path of the nasociliary nerve

A
  1. Gives off sensory branches
  2. Passes through anterior ethmoidal foramen
  3. Enters nasal cavity
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10
Q

What branch is given off the nasociliary nerve?

A

External nasal

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11
Q

Where does the external nasal nerve supply?

A

Skin of the nose

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12
Q

Where does the optic nerve enter the orbit?

A

Optic canal

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13
Q

What nerve accompanies the optic nerve in the optic canal?

A

Ophthalmic of trigeminal

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14
Q

What surrounds the optic nerve?

A

Meninges

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15
Q

Describe the course of the optic nerve within the optic canal

A
  1. Runs within the cone of recti muscles

2. Pierces sclera as a point medial to posterior pole of eyeball

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16
Q

What occurs when the optic nerve pierces the sclera?

A

The meninges and sclera fuse

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17
Q

What is the function of the optic nerve?

A

Transmits sensory information regarding brightness, red-green colour perception and visual field

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18
Q

What is papilledema?

A

Oedema of the optic disc

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19
Q

What is papilledema a sign of?

A

Elevated intracranial pressure

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20
Q

List 3 things which can cause papilledema

A
  1. Brain tumour
  2. Cerebral haemorrhage
  3. Cavernous sinus thrombosis
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21
Q

What are 2 symptoms of papilledema?

A
  1. Blurred vision

2. Double vision

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22
Q

Where does the oculomotor nerve leave the brainstem?

A

Between the midbrain and pons

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23
Q

How do the superior and inferior branches of the oculomotor nerve enter the orbit?

A

Superior orbital fissure

24
Q

What 2 muscles does the superior ramus of the oculomotor nerve supply?

A
  1. Superior rectus

2. Levator palpebrae superioris

25
Q

What 3 muscles does the superior ramus of the oculomotor nerve supply?

A
  1. Inferior rectus
  2. Medial rectus
  3. Inferior oblique
26
Q

What is the function of the branch from the nerve to inferior oblique?

A

Carries parasympathetic fibres to sphincter pupillae and ciliary body

27
Q

How does the trochlear nerve enter the orbit?

A

Superior orbital fissure above common tendinous ring

28
Q

Where does the abducent nerve leave the brainstem?

A

Junction of pons and medulla

29
Q

Describe the course of the abducent nerve after leaving the brainstem

A
  1. Enters cavernous sinus
  2. Reaches orbit through superior orbital fissure within common tendinous ring
  3. Passes laterally to supply lateral rectus
30
Q

What does paralysis of the abducent nerve cause?

A

Medial squint

31
Q

What does paralysis of the oculomotor nerve cause?

A

Lateral squint

32
Q

What does trochlear nerve palsy cause?

A

Double vision

33
Q

Why does trochlear nerve palsy cause double vision?

A

The weakened muscle prevents the eyes from moving in the same direction together

34
Q

Where does the ophthalmic artery originate?

A

Internal carotid artery

35
Q

Describe the course of the ophthalmic artery

A
  1. Passes beneath optic nerve
  2. Accompanies optic nerve through optic canal
  3. Curves over optic nerve from lateral to medial
36
Q

What are the 5 branches of the ophthalmic artery?

A
  1. Central retinal artery
  2. Lacrimal artery
  3. Ciliary arteries
  4. Supraorbital artery
  5. Supratrochlear artery
37
Q

Where does the lacrimal artery supply?

A

Lacrimal gland

38
Q

What are the 4 components of the lacrimal apparatus?

A
  1. Lacrimal gland
  2. Lacrimal canaliculi
  3. Lacrimal sac
  4. Nasolacrimal duct
39
Q

What is the function of the lacrimal apparatus?

A

Tear production and drainage

40
Q

What are 2 functions of the lacrimal gland?

A
  1. Secrete tears

2. Contains excretory ducts to convey fluid to surface of the eye

41
Q

What is the function of the nasolacrimal duct?

A

Conveys fluid to the nose, emptying in the inferior nasal conchae

42
Q

What is the function of blinking?

A

Moves tears from lacrimal gland to sac to keep eyeball moist

43
Q

What can occur if the eyeball dries out?

A

Corneal ulcers may form

44
Q

What are the 2 major veins of the orbit?

A
  1. Superior ophthalmic vein

2. Inferior ophthalmic vein

45
Q

What are the 2 communications of the ophthalmic veins?

A
  1. Cavernous sinus

2. Pterygoid venous plexus

46
Q

How do the ophthalmic veins communicate with the cavernous sinus?

A

Via superior orbital fissure

47
Q

How do the ophthalmic veins communicate with the pterygoid venous plexus?

A

Via inferior orbital fissure

48
Q

How is the superior ophthalmic vein formed?

A

Unification of supraorbital and supratrochlear veins

49
Q

What communication does the superior ophthalmic vein form?

A

Skin of the face and cavernous sinus

50
Q

Name 3 intrinsic muscles of the eye

A
  1. Ciliary muscle
  2. Constrictor pupillae
  3. Dilator pupillae
51
Q

What is the function of the ciliary muscle?

A

Accommodation of the lens

52
Q

Describe the innervation of the ciliary muscle

A

Parasympathetic innervation by the oculomotor nerve

53
Q

What is the function of the constrictor pupillae?

A

Constriction of the pupil

54
Q

Describe the innervation of the constrictor pupillae

A

Parasympathetic innervation by the oculomotor nerve

55
Q

What is the function of the dilator pupillae?

A

Dilation of the pupil

56
Q

Describe the innervation of the dilator pupillae

A

Parasympathetic innervation by the superior cervical ganglion