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Year 2- Anatomy > Anatomy of the Orbit > Flashcards

Anatomy of the Orbit Flashcards

1
Q

How many bones make up the orbit?

A

7

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2
Q

Name the seven bones which make up the orbit.

A

Frontal
Zygomatic
Lacrimal
Maxillary
Sphenoid
Ethmoid
Palatine

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3
Q

There are three foramina which allow neurovascular structures to enter the orbit. Name them.

A

Optic foramen
Superior orbital fissure
Inferior orbital fissure

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4
Q

The walls of the orbits are weak, especially the medial and inferior walls. Why is this?

A

Surrounded or adjacent to paranasal air sinuses

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5
Q

Which paranasal air sinus is just above the orbit?

A

Frontal air sinus

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6
Q

Which paranasal air sinus is just medial to the medial wall of the orbit?

A

Ethmoid air sinus

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7
Q

Which paranasal air sinus is just inferior to the floor of the orbit?

A

Maxillary air sinus

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8
Q

The eyeball is a lot smaller than the space of the orbit. What fills out the rest of the orbit?

A

Fat

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9
Q

What is the length of eyeball compared to the length of orbit?

A

Eyeball- 24mm
Orbit- 40mm

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10
Q

What does the fat in the orbit do?

A

Cushions the eyeball

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11
Q

If you see someone with sunken eyeballs, what can this tell us?

A

They are late in the process of starvation as the fat supplies of the orbit are some of the last stores to be used.

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12
Q

Compare the inside and outside of an eyelid.

A

Outside- skin
Inside- mucous membrane (conjunctiva)

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13
Q

What does the tarsal plate (solid plate) of the eyelid do?

A

Keeps shape of eyelid

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14
Q

What is the tarsal plate of the eyelid made of?

A

Dense connective tissue

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15
Q

What is found within the tarsal plate?

A

Meibomian glands

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16
Q

What is the function of meibomian glands?

A

Secretes oily substance which lines the tear film and prevents tears from evaporating

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17
Q

Which muscles opens and closes the eyes?

A

Orbicularis oculi

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18
Q

What happens if the Meibomian sebaceous glands are blocked?

A

Oily secretion is trapped inside and causes painful swelling

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19
Q

What happens to the conjunctiva after it lines the inner side of the eyelid?

A

Turns on itself at a point called the fornix.

Therefore, there is a superior and inferior fornix, a fold in which the conjunctiva turns and covers part of the sclera.

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20
Q

Why is the conjunctiva pink?

A

Many capillaries

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21
Q

What does the conjunctiva not cover?

A

The cornea as needs the light

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22
Q

What does the sclera have over it and how can you tell?

A

Conjunctiva- transparent but can see tiny blood vessels

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23
Q

Which gland forms tears?

A

Lacrimal gland

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24
Q

What is the parasympathetic innervation for the lacrimal duct?

A

Facial nerve (CN VII)

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25
Q

What do the tears formed in the lacrimal gland coat?

A

Outer surface of sclera, conjunctiva and cornea.
This is known as a tear film.

26
Q

What helps to spread the tear film around the anterior aspect of the eyeball?

A

Blinking

27
Q

What do tears drain through?

A

Punctae sitting at the medial side of each eyelid and then drains into the lacrimal sac.

28
Q

The lacrimal sac sits over the lacrimal bone. After the tears have drained into the lacrimal sac after the punctae, where do they drain to?

A

Through nasolacrimal duct into the inferior meatus.

29
Q

Just go over the pathway of tears.

A

From lacrimal gland -> coat eye -> drain into punctuae -> drain into lacrimal sac -> drain into nasolacrimal duct ->drain into inferior meatus

30
Q

What role does the orbicularis oculi have in tear production?

A

Squeezes lacrimal sac to release tears

31
Q

There are intrinsic and extrinsic ocular muscles. What do the intrinsic muscles help to control?

A

Control pupil diameter.
Move the eye to look in different directions

32
Q

Which muscles in the iris help to constrict the pupil?

A

Sphincter pupillae (constrictor pupillae).

33
Q

Which muscles in the iris help to dilate the pupil?

A

Dilator puplillae

34
Q

What type of innervation causes pupils to dilate?

A

Sympathetic innervation

35
Q

Therefore, which type of innervation supplies the dilator pupillae?

A

Sympathetic innervation

36
Q

Which type of innervation will supply the constrictor pupillae and ultimately cause the pupil to contrict?

A

Parasympathetic inneration

37
Q

Which nerve carries parasympathetic innervation to the constrictor pupillae?

A

Oculomotor nerve (CN III)

38
Q

Name the three intrinsic muscles.

A

Constrictor/sphincter pupillae
Dilator pupillae
Cililiaris muscle

39
Q

What is the specific role of the ciliaris muscle?

A

Helps to alter lens to focus on closer objects.

40
Q

Which type of innervation supplies the ciliaris muscle?

A

Parasympathetic innervation

-> both muscles beginning with C get parasympathetic innervation

41
Q

Which nerve supplies the parasympathetic innervation the the muscles of the eye?

A

CN III- oculomotor nerve

42
Q

What do extrinsic muscles do?

A

Muscles originate from the bony orbit and attach to the eyeball t help to move it.

43
Q
A
44
Q
A
45
Q

There are four straight extrinsic muscles called recti. Name them.

A

Medial rectus
Lateral rectus
Superior rectus
Inferior rectus

45
Q

There are two oblique extrinsic muscles. Name them.

A

Superior oblique
Inferior oblique

46
Q

Where do the recti muscles arise from?

A

Apex of the orbit from the annular fibrous ring.

47
Q

Which extrinsic oblique muscles enters the eye anteriorly?

A

Inferior oblique muscle

48
Q

Which extrinsic oblique muscles enters the eye posteriorly?

A

Superior oblique muscle

49
Q

There is another muscle which comes from the back of the orbit but attaches to the upper eyelid. What is it called?

A

Levator palpebrae superioris muscle

50
Q

What is the origin and insertion of the Levator palpebrae superioris?

A

Origin- roof of orbit
Insertion- upper eyelid

51
Q

What is the origin and insertion of the rector muscles?

A

Origin- tendinous ring
Insertion- sclera anteriorly

52
Q

What is the origin and insertion of the superior oblique muscle?

A

Origin- lesser wing of sphenoid
Insertion- sclera posteriorly

53
Q

What is the origin and insertion of the inferior oblique muscle?

A

Origin- medial part of orbit floor
Insertion- sclera posteriorly

54
Q

Which nerve supplies the superior oblique muscle?

A

Trochlear nerve (CN IV)

55
Q

Which nerve supplies the lateral rectus muscle?

A

Abducent nerve (CN VI)

56
Q

Which nerve supplies all the muscles of the eye except for the superior oblique and lateral rectus?

A

Oculomotor nerve (CN III)

57
Q

How many cranial nerves enter the orbit?

A

4

58
Q

Name the cranial nerves which enter the orbit.

A

Trochlear nerve (CN IV)
Oculomotor nerve (CN III)
Optic nerve (CN II)
Abducent nerve (CN VI)

59
Q
A

Year 2- Anatomy (14 decks)

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