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BIOL21402 > L9 & L10 - Vision III and IV > Flashcards

L9 & L10 - Vision III and IV Flashcards

1
Q

Visual Pathway: components

A

Optic nerve
Optic chiasm
Optic tract
Lateral Geniculate Nucleus/body
Optic Radiation
Visual Cortex

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2
Q

What happens to nasal retinal fibres and temporal retinal fibres at the optic chasm?

A

Nasal retinal fibres decussate - they cross over to the contralateral side

Temporal retinal fibres do not decussate - they remain ipsilateral

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3
Q

Nasal retinal fibres

A

Receives temporal sensory information

Decussate at the optic chiasm

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4
Q

Temporal retinal fibres

A

Receives nasal sensory information

Do not decussate at the optic chiasm

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5
Q

Visual Pathway lesions: the expected effects of total left eye field loss, bitemporal hemianopia, and right homonymous hemianopia

A

Anything that disrupts normal function

Total field loss of the left eye - Left eye visual information lost

Bitemporal hemianopia - temporal vision of both eyes lost

Right homonymous hemianopia - Nasal information of left eye lost, temporal information of right eye lost

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6
Q

Optic nerve: what is it, what is the space surrounding it continuous with, when do fibres become myelinated, and when does it exit the orbital cavity?

A

The nerve that carries visual information into the brain

The subarachnoid space surrounding it is continuous with intracranial subarachnoid space

Fibres only become myelinated after going through lamina cribrosa

Exits orbital cavity through the optic canal

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7
Q

Optic chiasm: what is it, where is it located anatomically, and what fibres travel through it?

A

Area of the visual pathway where nasal retinal fibres decussate

  • Lies within Circle of Willis (circle of arteries that supply the brain)
  • Inferior to chiasm is the pituitary gland
  • Superior to the chiasm is the 3rd ventricle

Nasal optic nerve fibres travel contralaterally here

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8
Q

Lateral geniculate nucleus: what is another name for it and where is it located?

A

Lateral geniculate body

Located on the posterior surface of the thalamus

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9
Q

Optic radiation: what is it also called, what does it do, where is it located, and where does it travel to?

A

Geniculocalcarine tract (ends up in calcarine sulcus and geniculo because it bends)

Takes information from LGN to the visual cortex

Located in the white matter of cerebral hemispheres

Travels to the occipital lobe (primary visual cortex)

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10
Q

Visual cortex: where is it located, what does it surround and what does it do?

A

Located in the occipital lobe

Surrounds calcarine sulcus (located on medial surface)

Receives input from LGN

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11
Q

Visual pathway: a sensory pathway

A

Photoreceptors -> bipolar cells -> ganglion cells -> cells of the LGN

The neurones are ordered 1ˢᵗ, 2ⁿᵈ, and 3ʳᵈ orders (photoreceptors are not counted)

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12
Q

Extraocular muscles: what are they?

A
  • Superior oblique (travel diagonal)
  • Inferior oblique
  • Superior rectus (travel straight)
  • Lateral rectus
  • Medial rectus
  • Inferior rectus
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13
Q

Trochlea: what is it?

A

Pulley-like structure in the eye that interacts with the superior oblique muscle

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14
Q

Superior oblique: where is its origin, what is its insertion, what movements does it allow, and what nerve is it innervated by?

A

Body of sphenoid

Superior posterolateral sclera

Primarily Intorsion, but secondarily abduction and depression

Trochlear nerve (CN4)

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15
Q

Superior rectus: where is its origin, what is its insertion, what movements does it allow, and what nerve is it innervated by?

A

Annulus of Zinn

Superior anterior sclera

Primarily elevation, but secondarily adduction and intorsion

Oculomotor nerve (CN3)

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16
Q

Lateral rectus: where is its origin, what is its insertion, what movements does it allow, what unusual feature does it have, and what nerve is it innervated by?

A

Annulus of Zinn

Lateral anterior sclera

Abduction

Only supplied by one artery

Abducens nerve (CN6)

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17
Q

Medial rectus: where is its origin, what is its insertion, what movements does it allow, and what nerve is it innervated by?

A

Annulus of Zinn

Medial anterior sclera

Adduction

Oculomotor nerve (CN3)

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18
Q

Inferior rectus: where is its origin, what is its insertion, what movements does it allow, and what nerve is it innervated by?

A

Annulus of Zinn

Inferior anterior sclera

Primarily depression, but secondarily extorison and adduction

Oculomotor nerve (CN3)

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19
Q

Inferior oblique: where is its origin, what is its insertion, what movements does it allow, and what nerve is it innervated by?

A

Anterior orbital floor

Inferior posterolateral sclera

Primarily extorsion but secondarily abduction and elevation

Oculomotor nerve (CN3)

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20
Q

What type of eye movements are there and what do they mean?

A

Elevation - lifting up
Depression - pulling down
Extorsion - temporal rotation (away from nose)
Intorsion - medial rotation (towards nose)
Adduction - medial movement (towards the nose)
Abduction - temporal movement (away from the nose)

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21
Q

Levator Palpabrae Superioris: what is it, and what is its origin?

A

Not an extraocular muscle, lifts eyelids superiorly but does not act directly on eyes

Origin: lesser wing sphenoid, superior & anterior to optic canal

22
Q

Annulus of Zinn: what is it and where is it located?

A

Thickening of periosteum surrounding optic canal and a large portion of the inferior part of the superior orbital fissure (does not interact with the inferior orbital fissure)

23
Q

Optic canal: which nerve travels through it and what artery travels through it?

A

CN 2 - optic nerve

Ophthalmic artery

24
Q

Superior orbital fissure: which nerve travels through it and what artery travels through it?

A

CN 3 - oculomotor (has an upper and lower division travelling through)
CN 4 - Trochlear nerve
CN 5 - all three branches of the ophthalmic division of the trigeminal nerve (lacrimal, frontal, and nasociliary nerves (moving superiorly to inferiorly))
CN 6 - Abducens nerve

25
Q

Eyebrows: what muscles do they have and what movements do they allow?

A
  • Occipitofrontalis - raises brow
  • Procerus - pulls medial brow inferiorly
  • Orbicularis oculi - lowers brow (surrounds the eye, allows blinking)
  • Corrugator supercilialis - pulls brow medially
26
Q

Occipitofrontalis: what does it do, what is its origin, what does it insert on, and what nerve innervates it?

A

Raises brow

Highest nuchal bone in the occipital bone

Epicranial aponeurosis

CN VII - facial nerve

27
Q

Procerus: what does it do, what is its origin, what does it insert on, and what nerve innervates it?

A

Pulls medial brow inferiorly

Nasal bone

Medial side frontalis

CN VII - facial nerve

28
Q

Orbicularis oculi: what does it do, what is its origin, what does it insert on, and what nerve innervates it?

A

Lowers brow, surrounds eye, allows blinking

Palpebral - medial palpebral ligament
Orbital - medial palpebral ligament and bone

Palpebral - lateral palpebral raphe
Orbital - loops to the origin

CN VII - facial nerve

29
Q

Palpebral ligaments

A

Palpebral ligaments
Medial ligament attaches onto lacrimal crest
Lateral ligament attaches onto zygomatic bone

30
Q

Corrugator supercilialis: what does it do, what is its origin, what does it insert on, and what nerve innervates it?

A

Pulls brow medially

Superciliary arch on the frontal bone

Skin medial eyebrow

CN VII - facial nerve

31
Q

Anterior view of the eye: the features that can be seen

A

Upper lid
Lower lid
Palpebral fissure - the area between lids
Medial canthus - where eyelids meet medially
Lateral canthus - where eyelids meet laterally

Medial caruncle - modified skin, allows tears to drain through
Plica semilunaris - fold of the conjunctiva, allows full lateral movement of the globe

32
Q

Components of the eyelids: anteriorly to posteriorly

A

1 - Skin
2 - Subcutaneous tissue
3 - Orbicularis oculi - sphincter muscle
4 - Tarsal plate
5 - Tarsal (smooth) muscle - within tarsal plate
6 - Conjunctiva

Watch leccy - i stopped paying attention

33
Q

Tarsal plates

A

strengthened bands of connective tissue
provide structure and shape

34
Q

Tarsal glands

A

Mebomian glands

Yellow streaks within the plates

sebaceous glands
secrete outer layer of tear film

35
Q

Lacrimal apparatus

A

Sac
Puncta
Nasolacrimal duct
Canaliculi

36
Q

Sac

A

sits in lacrimal fossa
composed of fibroelastic tissue
- medial palpebral ligament straddles sac

37
Q

Puncta

A

tear drainage holes
located on lacrimal papillae

38
Q

Nasolacrimal duct

A

delivers tears into inferior nasal meatus
valve prevent reflux of tears into duct

39
Q

Canaliculi

A

tubes that drain tears from puncta into lacrimal sac
walls contain elastic tissue
surrounded by fibers of OO

40
Q

Tear film composition

A
  • Oil
  • Water
  • Mucin
41
Q

Oil in tear film

A

produced by the tarsal, sweat & sebaceous glands
0.2-0.9 micrometers thick
stops watery layer from evaporating
enables smooth eye movements

42
Q

Water in tear film

A

produced by the lacrimal gland
6.5-7.5 micrometers thick
protects against infection (due to presence of beta lysin, immunoglobulins & lysozyme)

43
Q

Mucin in tear film

A

Produced by the conjunctival goblet cells
- 0.5micrometers
- Wets microvilli of corneal epithelium
- Helps adhesion of tears to ocular surface
- Traps bacteria/dirt

44
Q

Ophthalmic artery: where does it come from, how does it interact with the optic nerve, and what does it divide into?

A

Divises from the internal carotid artery

Travels alongside optic nerve until about halfway before passing over it superiorly

  • Central retinal artery - travels within the optic nerve, supplying it
  • Lacrimal artery - travels anteriorly and supplies lacrimal gland (gland involved in tear formation)
  • Muscular branch - supplies extraocular muscles and later on becomes anterior ciliary arteries
  • Long posterior ciliary arteries - leccy
  • Medial palpebral artery - supply the medial half of the eyelids
  • Supraorbital artery - supplies the parts around the upper lid and eyebrows
45
Q

Central Retinal Artery: what bifurcation occurs and what is significant about these arteries?

A

Travels within the optic nerve before it bifurcates into superior temporal, superior nasal, inferior temporal, and inferior nasal arteries each supplying one quadrant of the eye

End arteries - no anastomoses - if arteries get blocked, parts of the vision may get compromised (backup ciliary arteries may help, though)

46
Q

SPCA: what are they, how many of them, where are they found, how do they enter the eye, where do they travel to, and what significant features do they have?

A

Short Posterior Ciliary Arteries

10-20 surrounding the optic nerve

Lamina cribrosa

Travel through the choroid until reaching the eyeball equator

Anastamose to form the ring of Zinn

47
Q

LPCA: what are they, how many of them, where are they found, how do they enter the eye, where do they travel to, and what significant features do they have?

A

Long posterior Ciliary Arteries

Only 2 surrounding the optic nerve - further away from it from the SPCA though

Lamina cribrosa

Travels through the choroid - enters the anterior chamber of the eye, and anastomose with anterior ciliary arteries as well as bifurcating into two more vessels which supply the anterior segment

48
Q

Anterior ciliary arteries: where do they come from and what parts of the eye do they supply?

A

Muscular artery goes through muscle and once passed through, becomes anterior ciliary artery

1 - Episcleral ring - stay superficial to the eyeball (responsible for bloodshot eyes)
2 - Arterial rings of iris - major and minor rings
3 - Intramuscular arterial ring - heads towards ciliary body

49
Q

What vessels are responsible for bloodshot eyes?

A

Episcleral vessels of the anterior ciliary arteries

50
Q

Major and minor arterial rings of the iris: how is the major ring formed, how is the minor ring formed, and why are the connections between rings helpful?

A

LPCAs anastomose with anterior ciliary arteries, forming the major ring surrounding the iris

These arteries then branch from the outer iris to the inner iris where they form the minor branch

These arteries connect the rings with a spiral pattern which allows for lengthening/moving back as the pupils dilate/constrict

51
Q

Veins of orbit: what veins are there, and what divisions arise from each quadrant?

A

Vortex vein - one for each quadrant, drains all blood from veins within the eye - these veins progressively get bigger along the drainage pathway

Superior quadrants drain into one or two superior ophthalmic veins - drains superior vortex veins, drains into the cavernous sinus

Inferior quadrants drain into two ophthalmic vein - the two veins drain into the cavernous sinus

BIOL21402 (12 decks)

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