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Anatomy Unit 2 > Eye & Orbit > Flashcards

Eye & Orbit Flashcards

1
Q

What three bones make up the margin of the orbit?

A

Frontal, zygomatic, maxillary

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2
Q

What bones make up the medial wall of the orbit?

A

Lesser wing of sphenoid, ethmoid, lacrimal, maxillary

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3
Q

What bones make up the superior wall of the orbit?

A

Frontal bone

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4
Q

What bones make up the lateral wall of the orbit?

A

Zygomatic bone and greater wing of sphenoid bone

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5
Q

What makes up the inferior wall of the orbit?

A

Zygomatic bone, maxilla, and palatine bone!!!

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6
Q

Where is the optic canal and what courses through it?

A

It is superior to the superior orbital fissure, within the greater wing of the lesser wing of the sphenoid bone.
CN2 (optic) and ophthalmic artery pass through

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7
Q

What is the superior orbital fissure and what courses through it?

A

Between the greater and lesser wing of the sphenoid bone. Contains V1, CN3, CN4, and CN6, as well as the superior ophthalmic vein

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8
Q

What is the inferior orbital fissure and what goes through it?

A

Space between the maxilla and inferior aspect of greater wing of sphenoid bone. Contains infraorbital nerve and inferior ophthalmic vein, as well as zygomatic nerve

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9
Q

Where are the anterior and posterior ethmoidal nerves (V1) and arteries going through?

A

Anterior and posterior ethmoidal foramina, which is between the frontal and ethmoid bones on the medial wall.

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10
Q

What is the lacrimal canal?

A

Canal anterior to the lacrimal bone on the medial wall, for the lacrimal duct

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11
Q

What is the infraorbital groove?

A

Groove found in floor of orbit to allow infraorbital nerve (V2) to enter suborbital region of the face`

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12
Q

What is the supraorbital notch/foramen?

A

Part of frontal bone, exit site for supraorbital nerve (V1, frontal) and supraorbital artery (ophthalmic)

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13
Q

Where is the fossa for the lacrimal sac?

A

Lateral, just deep to the superior orbital rim of the frontal bone

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14
Q

Which ligaments does the orbicularis oculi attach to?

A

Exposed medial palpebral ligament, It covers the lateral palpebral ligament and attaches to it inferiorly.

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15
Q

What are the attachments of the lateral and medial palpebral ligaments, and what do they hold up?

A

Lateral - zygomatic bone
Medial - maxilla

The hold up the superior and inferior tarsal plates, with the help of the underlying orbital septum

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16
Q

What does the tendon of the levator palpebrae superior muscle attach directly to?

A

the superior tarsal plate

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17
Q

What do the parts of the orbicularis oculi muscle attach to?

A

Orbital: Orbital septum and rim of bony orbit
Palpebral: Attaches to the tarsal plates

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18
Q

What is the levator palpebrae superioris, insertions action and innervation?

A

Origin: Posterior roof of orbit
Insertion: superior tarsal plate
Action: Elevation of upper eyelid
Nerve: Oculomotor (CN3)

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19
Q

What is the superior tarsal muscle?

A

Muscle aids in elevating upper eyelid, provides muscle tone to upper lid and is innervated by post-ganglionic sympathetics

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20
Q

What are striations in the palpebral conjunctiva?

A

The Meibomian glands of the tarsal plate. They each have a tarsal duct that they empty into, and are modified sebaceous glands

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21
Q

Where does the lacrimal gland empty?

A

it has 3-9 ducts that empty laterally along the lateral superior conjunctive fornix

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22
Q

What is the ANS innervation of the lacrimal gland?

A

PANS only to increase secretion
CN7 to greater petrosal
Greater petrosal to nerve of pterygoid canal
Nerve of pterygoid canal to synapse in PT ganglion
PT ganglion to zygomatic nerve
Zygomatic nerve to lacrimal nerve
Lacrimal nerve to lacrimal gland

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23
Q

How does the lacrimal apparatus work?

A

Caruncle blocks the two medial openings (punctae) to the canaliculi, two small channels that drain into the lacrimal sac.
When you close your eye, the lacrimal orbicularis oculi muscle expels whatever contents are currently in the nasolacrimal duct and builds a vacuum.
When you open your eyes, tears flow from the lacrimal lake into the lacrimal duct for next expulsion (due to the vacuum previously created).

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24
Q

What structures does the dura become in the eye?

A

Periosteal layer - becomes periorbital which is continuous with orbital septum.
Also forms optic nerve sheath (which also has pia mater, arachnoid mater, and CSF) and common tendinous ring, which is that attachment for the 4 rectus muscles.

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25
Q

What is Tenon’s capsule and what does it invest?

A

It is a fascial sheath attaching to the sclera of the eye that invests all 6 extrinsic ocular muscles, but NOT the levator palpebrae superioris muscle.

There is a space between it and the eyeball so that the eyeball can move freely

26
Q

What are the medial and lateral check ligaments? What do they form inferiorly?

A

Structures formed by fascial sheath of eye (Tenon’s capsule) that invest the medial and lateral rectus.

Inferiorly they form the suspensory ligament - thickening that forms cradle-like structure to suspend eye in the orbit

27
Q

What is the retrobulbar fat?

A

Fat lying in posterior orbit external to tenon’s capsule which helps form a cup-like socket to cushion and aid in eye movement

28
Q

What muscles arise from the common tendinous ring (CTR) and where does it attach?

A

All 4 rectus muscles arise from CTR, which is an extension of the dura. It attaches to the posterior bony orbit, enclosing the optic canal and part of the superior orbital fissure

29
Q

What muscles have origins outside the CTR?

A

Superior and inferior oblique, and levator palpebrae superioris (not an eye muscle)

30
Q

What is the trochlea?

A

The medial cartilagenous attachment of the inferior oblique

31
Q

Where does the superior oblique origin and insert?

A

Origin: Posterior bony orbit, above optic canal
Insertion: Posterior superolateral surface of eye

32
Q

Where does the inferior oblique origin and insert?

A

Origin: Floor of orbit lateral to lacrimal groove
Insertion: Lateral inferior surface of sclera

33
Q

How do you test cranial nerve 4?

A

Make patient look medially and downward - superior oblique

34
Q

How do you test cranial nerve 6?

A

Make patient look laterally

35
Q

How do you test the superior rectus?

A

Make patient look laterally and upward

36
Q

How do you test the inferior rectus?

A

Make patient look laterally and downward

37
Q

How do you test the inferior oblique?

A

Make patient look medially and upward

38
Q

What does each division of the CN3 innervate and where does it split?

A

It goes in through the CTR and splits to superior and inferior divisions
Superior: Superior rectus and levator palpebrae superioris
Inferior: Inferior rectus, medial rectus, and inferior oblique

39
Q

Where does the optic nerve pass and what invests it?

A

Thru optic canal and CTR, invested by all three meningeal layers and is thus bathed in CSF up to the eye level

40
Q

Why are eye muscle movements complex?

A

Because eye muscles originate at a 25 degree angle to the midsagittal plane, which the eye needs to be parallel to

41
Q

Where does the trochlear nerve course?

A

Enters through superior orbital fissure but superior to CTR. Crosses levator palpebrae superioris muscle superiorly and innervates the SO muscle along its superior surface

42
Q

Where does the abducent nerve course?

A

Enters orbit through the SOF and passes within the CTR, innervates LR muscle along its medial side. It is between the two oculomotor divisions

43
Q

What are the three branches of the ophthalmic nerve (V1) and where does this occur?

A
  1. Frontal
  2. Nasociliary
  3. Lacrimal
    Splits just before entering the superior orbital fissure
44
Q

Where does the frontal nerve course? What branches does it give?

A

Branch of V1 before SOF, runs between trochlear nerve and lacrimal nerve outside CTR. Runs on top of levator palpebrae superioris
Branches:
1. Supratrochlear - more medial
2. Supraorbital

45
Q

Where does the nasociliary nerve course? What branches does it give?

A

Branch of V1 before SOF, runs through CTF, medial to abducent nerve.
Branches:
1. Anterior ethmoidal
2. Posterior ethmoidal (Foramina for both in ethmoid bone)
3. Long ciliary nerves (2-4) to posterior surface of eye
4. Ciliary ganglion branch (delivers sensory to cornea via short ciliary nerves)
5. Infratrochlear nerve - terminal branch

46
Q

Where does the lacrimal nerve course? What is its function?

A

Branch of V1, enters through SOF superior to CTF. Goes along superior surface of lateral rectus, providing sensory to the region. Also delivers PANS (CN7) post-ganglion fibers riding on zygomatic nerve (V2) to the lacrimal gland

47
Q

What is the ciliary ganglion?

A

PANS ganglion suspended by ciliary ganglion root, which is sensory branch of nasociliary (V1). It gives rise to 3-5 short ciliary nerves which carry sensory from V1 and PANS for:

  1. Ciliary muscle
  2. Sphincter pupillae muscle
48
Q

What nerves provide sensory to the lids?

A

Upper: Lacrimal, supraorbital / supratrochlear (frontal), infratrochlear (nasociliary) (V1)
Lower: Mostly infraorbital (V2)

49
Q

What provides the innervation for the ciliary muscle + sphincter pupillae?

A

Superior CN3 PANS via ciliary ganglion to short ciliary nerves

50
Q

What provides innervation for the dilator pupillae?

A

SANS somehow, with sympathetic fibers going through both long and short ciliary nerves (branches of nasociliary nerve, V1) from the nasociliary nerve in the first place

51
Q

What are the actions of the two muscles fibers runnings of the ciliary muscle?

A
  1. Circular fibers - constrict to release tension on zonular fibers, allowing accommodation
  2. Longitudinal fibers - control flow of aqueous humor to the canal of Schlemm
52
Q

What are the branches of the ophthalmic artery? What is its course?

A

Goes through CTR, giving rise to central retinal artery. Also gives rise once inside the orbit to:

  1. Lacrimal
  2. Short ciliary
  3. Long ciliary
  4. Supraorbital
  5. Supratrochlear
  6. Anterior ethmoidal
  7. Posterior ethmoidal
53
Q

What is the central retinal artery?

A

Only blood supply to inner 2/3 of retina, a branch of ophthalmic artery

54
Q

What are the two major ophthalmic veins? Where do they run relative to the CTR?

A
  1. Superior ophthalmic vein - superior to CTR

2. Inferior ophthalmic vein - inferior to CTR

55
Q

Where does superior ophthalmic vein drain?

A

Anastomoses with supraorbital vein and nearby veins, drains into cavernous sinus

56
Q

Where does inferior ophthalmic vein drain? Why is this important?

A

Anastomoses with angular vein, infraorbital vein, and pterygoid venous plexus. Drains into cavernous sinus.

This is important because it’s a potential route for spread of infection to brain.

57
Q

What is papilledema?

A

Edema of optic disc due to increase cranial pressure, since CSF follows CN2 to back of retina. Venous drainage will be under pressure and will show on optic disc as an “outie”

58
Q

What does the absence of the pupillary light reflex in unconscious patient mean?

A

There is damage to the midbrain, where the nucleus for the CN3 PANS is - the Edinger-Westphal Nucleus

59
Q

What could nystagmus indicate?

A

CN8 (Vestibular) malfunctioning - something to do with balance. More on this in neuroscience

60
Q

Why can you still close your lids in Bell’s palsy?

A

Upper lid will close: Oculomotor innervation of LPS, and sympathetic input to superior tarsal muscle
Lower lid will not close: Palpebral part of orbicularis oculi

61
Q

Why do you have excess tearing in Bell’s palsy?

A

Lacrimal part of orbicularis oculi is not functioning properly, so tears are not suctioned out right, and there is a buildup of lacrimal lake

62
Q

Why do black eyes happen?

A

Loose connective tissue around orbital part of eye is thin, and skin is loosely attached to orbicularis oculi, allowing blood to accumulate form nearby injury

Anatomy Unit 2 (13 decks)

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