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Systems: Neurology AB > The Orbit > Flashcards

The Orbit Flashcards

1
Q

What bones form the orbit?

A
  • Frontal
  • Sphenoid
  • Lacrimal
  • Ethmoid
  • Maxillary
  • Zygomatic
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2
Q

What are the 3 holes in the orbit?

A
  • Optic foramen
  • Superior orbital fissure
  • Inferior orbital fissure
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3
Q

What is the orbit closely related to?

A

Air sinuses

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4
Q

What walls of the orbit are particularly weak?

A

Medial and inferior walls

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5
Q

What makes the walls of the orbit susceptible to injury

A

The presence of the paranasal air sinuses and the thin bone which separates them from the orbit

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6
Q

What cushions the globe?

A

Orbital fat

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7
Q

What does the orbital fat do?

A

Supports the globe

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8
Q

What is the AP length of the eyeball?

A

~24mm

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9
Q

What is the AP length of the orbit?

A

~40mm

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10
Q

When would the eyeball have a protruding appearance?

A

If the orbital fat was hypertrophied such as in thyroid eye disease?

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11
Q

What may very sunken eyes indicate?

A

The person has been losing a lot of body weight as it is one of the last fat reserves to go

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12
Q

What is on the outside of the eyelids?

A

-Skin (typically with hair follicles and sebaceous glands)

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13
Q

What is on the inside of the eyelids?

A

Mucous membrane known as conjunctiva

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14
Q

What must the conjunctiva be able to do?

A

Be wet and secret fluid

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15
Q

What is always found with the eyelashes?

A

Sebaceous glands

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16
Q

What happens when the sebaceous glands get blocked?

A

They get inflamed and enlarged forming styes

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17
Q

What muscle elevates the superior eyelid?

A

Levator palpebrae superioris

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18
Q

What muscle lies just anterior to the LPS and is involved in closing the eye?

A

Orbicularis oculi

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19
Q

What innervates the orbicularis oculi?

A

Facial nerve

20
Q

What plate is located in the eyelid?

A

Tarsal plate

21
Q

What is the function of the tarsal plate?

A

To keep the shape and provide firmness to the eyelid

22
Q

What glands are found within the tarsal plate?

A

Meibomian glands

23
Q

Conjunctiva

A

Thin vascular membrane that covers the inner surface of the eyelids and loops back over the sclera

24
Q

What does the conjunctiva not cover?

A

Cornea

25
Q

Fornix

A

Area with an angle

26
Q

Why would you not want conjunctiva over the cornea?

A

The conjunctiva is very vascular and blood vessels especially capillaries often leak which would decrease the amount and quality of light passing through the cornea

27
Q

Conjunctivits

A

Inflammation of the conjunctiva

28
Q

Where is the lacrimal gland situated?

A

In the orbit laterally

29
Q

What innervates the lacrimal gland?

A

Parasympathetic innervation (pre-ganglionic) via the facial nerve

30
Q

What does the lacrimal gland duct open into?

A

Conjunctival sac

31
Q

What happens when you blink?

A

The eyelids spread tears evenly on the surface of the cornea

32
Q

Where do tears drain through?

A

Punctae on the medial side of each eyelid

33
Q

What does the punctae drain into?

A

Lacrimal sac

34
Q

Where does the lacrimal sac sit?

A

Over the lacrimal bone

35
Q

What does the lacrimal sac drain into?

A

Drains through the nasolacrimal duct into the inferior meatus of the nasal cavity

36
Q

What happens to the lacrimal sac when the orbicularis oculi contracts?

A

It opens the lacrimal sac when it contracts which creates a negative pressure which sucks in the tears

37
Q

What do intrinsic ocular muscles do?

A

Control pupil diameter and helps alter lens curvature to enable us to see near objects

38
Q

What do extrinsic ocular muscles do??

A

Move the eye

39
Q

What does the optic nerve carry?

A

Visual impulses from the eyeball

40
Q

What does the optic nerve leave the orbit through?

A

Optic foramen

41
Q

Where does the trochlear nerve arise from?

A

The dorsal part of the midbrain

42
Q

What ocular muscle does the trochlear nerve supply?

A

The superior oblique

43
Q

What ocular muscles does the oculomotor nerve supply?

A
  • Inferior oblique
  • Medial rectus
  • Superior rectus
  • Inferior rectus
  • Levator palpebrae superioris
44
Q

Where do the parasympathetic fibres carried by the oculomotor nerve synapse?

A

Ciliary ganglion in the orbit

45
Q

What ocular muscle does the abducent nerve supply?

A

Lateral rectus

Systems: Neurology AB (51 decks)

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