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(4) Head & Neck - Sessions > (5.1) The Eyes > Flashcards

(5.1) The Eyes Flashcards

0
Q

What structure runs in the Optic Canal?

A

Optic nerve

Arteries & Veins to the Retina

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1
Q

What are the main bones make up the orbit?

A
  • Roof: Frontal
  • Floor: Maxilla
  • Medial: Ethmoid
  • Lateral: Zygomatic
  • Sphenoid (roof & lateral)
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2
Q

What structures run the Superior Orbital Fissure?

A
  • Lacrimal N
  • Frontal N
  • Trochlear N (CN XI)
  • Superior br. Of Oculomotor N (CN III)
  • Nasociliary N
  • Inferior br. Of Oculomotor N (CN III)
  • Abducens N (CN XI)
  • Opthalmic V
  • Sympathetic Nerves

Large French Teenagers Sit Numb In Anticipation Of Sweet

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3
Q

What is the happens in the Optic Chiasma? Hence what function does it achieve?

A

Optic nerve fibres PARTIALLY cross within it, to allow the visual cortex to receive the same hemispheric visual field from both eyes

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4
Q

What is a blow out fracture?

A

A fracture that displaces the orbital walls (usually medial and inferior, the weakest bones) and its contents

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5
Q

Which two ways may an infection from the orbit spread to cause meningitis?

A
  • The Optic nerve is covered by the maters of the meninges e.g. continuous with the brain
  • The Opthalmic V that drains the eyes continues into Cavernous Sinus, which in connected to the cranial cavity
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6
Q

How may a raised intracranial pressure affect the eyes?

A
  • The Optic nerve is surrounded by the meninges with CSF
  • Compression to the Optic Nerve -> compression to arteries supplying retina -> necrosis -> blind
  • Occluded vein -> Papilloedema (Oedema of optic disc) + Venous engorgement
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7
Q

The medial and inferior are the weakest Orbital walls, what structures are likely to be involved by each if they are fractured?

A
  • Medial -> Ethmoidal & Sphenoidal paranasal sinuses

- Inferior -> Maxillary paranasal sinuses

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8
Q

What are the 7 extraocular muscles? What are their innervations and actions?

A
  • Superior Rectus - Oculomotor (CN III) - Look up
  • Inferior Rectus - Oculomotor (CN III) - Look down
  • Lateral Rectus - Abducens (CN XI) - Abduct
  • Medial Rectus - Oculomotor (CN III) - Adduct
  • Inferior Oblique - Oculomotor (CN III) - Extorsion (Look up + out)
  • Superior Oblique - Trochlear (CN IV) - Intorsion (Look down + out)
  • Levator Palpebrae Superioris - Oculomotor (CN III) - Lifts upper eyelids

LR6 SO4 R3

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10
Q

What are the blood supplies and venous drainages of the retina?

A
  • Opthalmic A -> Central A of retina (an end artery)

- Central V of retina -> directly to Cavernous Sinus or via Opthalmic V (through Superior Orbital Fissure)

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11
Q

What is the Optic disc?

A

Optic disc = opening of Optic Canal at the cranial end eg

  • Exit for axons of the Optic Nerve
  • Exit of the major veins draining the retina
  • Entrance of the major blood vessels of the retina
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12
Q

What is Ptosis? What are the possible causes?

A

Ptosis = dropping of the upper eyelids

  • Damage of Oculomotor N -> Paralysis of Levator Palpebrae Superioris
  • Horner’s Syndrome -> Lost of Sympathetic fibres -> Paralysis of Superior Tarsus -> partial ptosis
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13
Q

Where are the Tarsal glands located? What is their function?

A
  • Within the Superior Tarsal

- Secrete oil, which helps to keep water in the eyes

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14
Q

What are the 4 structures in the Lacrimal Apparatus? Describe their roles individually.

A
  • Lacrimal gland: secretes Lacrimal fluid (tears)
  • Lacrimal ducts: drains into Conjunctival Sacs
  • Lacrimal Canaliculi: drains into Lacrimal Sac (at the medial angle of the eyes)
  • Nasolacrimal duct: drains into the Inferior Nasal Meatus (inferior to the inferior nasal concha)

https://www.healthtap.com/user_questions/188124

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15
Q

What extrocular muscles are used when you look to the left?

A
  • Left eye: Lateral rectus

- Right eye: Medial rectus

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16
Q

Which Sensory neurone and which Motor neurone are involved in corneal blinking reflex?

A
  • Sensory: CN Vi, Opthalmic N sensing irratation to the Cornea
  • Motor: CN VII, Facial N supplying Orbicularis Oculi
17
Q

What innervates for tear production? What are its functions?

A
  • Parasympathetic fibres of Facial Nerve CN VII
  • Provide nutrients & oxygen to Cornea
  • Contains bactericidal lysozymes
18
Q

Why may a patient with a damaged Oculomotor Nerve presents with a dilated pupil?

A

Paralysis of Sphincter Pupillae, unopposed action from Dilator Pupillae

19
Q

What is Stye?

A

Infection of the Sebaceous gland at the base of eyelash (針眼)

20
Q

What is Exopthalmos? What are the possible causes bilaterally and unilaterally?

A
  • Bilateral: Grave’s Disease (Hyperthyroidism)

- Unilateral: Aneurysm/Haematoma

21
Q

What is Horner’s Syndrome? What are the signs and symptoms?

A

Horner’s Syndrome = interruption of a cervical sympathetic trunk, hence lost of functions on the IPSILATERAL (same) side of the head

  • Miosis: constricted pupil due to unopposed action of Sphincter Papillae
  • Partial Ptosis: partial dropped upper eyelid due to paralysed Superior Tarsal (not a complete ptosis, levator palpebrae superioris unaffected)
  • Temperature & redness: due to vasodilation
  • Anhydrosis: absence of sweating
22
Q

What is Exposure Keratitis? What is Ectropion?

A

Exposure Keratitis = dried out cornea

Ectropion = ulcerated corneal surface

23
Q

Why may a disruption to the central artery of the retina cause immediate blindness?

A

It’s an end artery

24
Q

What are the structures that form the protective layer of the eyes? What are their roles?

A
  • Posteriorly: Sclera, provide attachment for extraocular muscles
  • Anteriorly: Cornea, a transparent refractive medium
25
Q

What structures form the middle vascular layer of the eyes? What is each of their functions?

A
  • Iris: consist Sphincter & Dilator Pupillae that determines the amount of light enters the eyes
  • Choroid: the largest vascular layer
  • Ciliary Body (anterior endings of Choroid): contract to control the shape of the lens, hence to focus the light onto retina
26
Q

What causes an Open Angle Glaucoma?

A
  • The drainage of Aqueous Humour is blocked at the Trabecular Meshwork/Scleral Venous Sinus, hence increasing intra-ocular pressure
27
Q

What produces Aqueous Humour and how is it drained?

A
  • Produced by Ciliary Processes -> Posterior Chamber -> through Lens -> Anterior Chamber
  • Drains into Trabecular Meshwork -> Scleral Venous Sinus
28
Q

What happens in the lens when someone is reading? Through which nerve it is achieved?

A
  • Parasympathetic input -> Oculomotor nerve -> Ciliary Body contract -> Lens become fat -> light is refracted more -> focus on Retina
29
Q

What are the cells that are found in Retina that are responsible in providing vision? Where is vision the most acute?

A
  • Photoreceptors
  • Rods: sensitive to low light, sees black and white
  • Cons: sensitive to bright lights, sees colours
30
Q

What are the two main spots that are seen in a fundoscopy? Where are they seen from a fundoscope? What are their roles?

A
  • Optic Disc (Blind Spot), found on nasal side: entrance/exits for neurovasculatures of the Retina
  • Macula found laterally to Optic disc: high density of Cones, serve for acuity of vision
31
Q

How do you test Superior Oblique muscle?

A
  • Ask the patient to look medially (adduct) first
  • Then ask the patient to look down

e.g. The downward action isn’t by Inferior Rectus

(4) Head & Neck - Sessions (11 decks)

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