Self Study Flashcards

1
Q

Where does the retina end anteriorly?

A

At the Ora Serrata, just in front of the equator of the eye

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2
Q

Function of the Humours of the eye?

A

Aqueous humor maintains intraocular pressure

Vitreous Humor cushions the retina

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3
Q

Describe the passage of the Aqueous Humor?

A
  • Produced in ciliary body
  • Feeds into posterior chamber
  • Passes into anterior chamber throught he pupil in front of the lens
  • Passes out the angle of the anterior chamber through the trabecular meshwork
  • Finally drains out Schlemm’s canal into the episcleral veins
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4
Q

What pathologies are visible in relation to the orbital fat?

A

Starvation/malnutrition - If the eyes look sunken it can mean the person is using up their orbital fat which is one of the last stores to go

Thyroid disease - Orbital fat hypertrophy -> Staring protruding eye appearance

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5
Q

What glands exist in the eyelid?

A

Sebaceous glands at the base of the eyelashes (blockage = external stye)

Meibomian Glands (in the tarsal plate) produce the oily layer of the tear film

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6
Q

What is the tarsal plate?

A

A layer of dense connective issue that gives the eyelid shape

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7
Q

What is conjunctiva?

A

A thin vascular membrane covering the inner surface of the eyelid and the sclera (but not a cornea)

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8
Q

Whats the reason for the conjunctiva not covering the cornea?

A

Its very vascular (and capillaries leak) so it would obstruct the transparent nature of the cornea

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9
Q

Where is the lacrimal gland and how is it innervated?

A

Lateral roof of the orbit

Parasympathetic fibres from the Facial Nerve

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10
Q

Where do the lacrimal ducts open into the orbit?

A

The superior conjuncitval fornix (reflection)

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11
Q

How do excess tears drain?

A

Through punctae on the medial side of each eyelid into the lacrimal sac (over lacrimal bones) and down the nasolacrimal duct into the Inf meatus

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12
Q

Explain the innervation of the intrinsic eye muscles

A

Ciliaris & Constrictor Pupillae = Parasympathetic fibres from Cr N III

Dilator Pupillae = Sympathetic fibres from a plexus around blood vessels

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13
Q

Where do the extraocular muscles originate?

A

Recti- originate in the apex of the orbit and come to attach to the front of the sclera

2 oblique:
Superior: starts at apex, runs medially, attaches at the trochlea, shifts direction and comes to bind to the sclera at the back

Inferior: Starts ar the front of the eyeball, swings underneath the eyeball to attach the the back of the sclera

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14
Q

What does the oculomotor nerve carry?

A
Mostly somatic motor innervation to the extraocular muscles.
Some Parasympathetic (Autonomic Motor) fibres --> Synapse at ciliary ganglion --> Ciliaris/Constrictor Pupillae
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15
Q

What are the branches of the ophthalmic nerve to the orbit and what do they do?

A

Enters through Sup Orbital Fissure

  • > Nasocilliary nerve
  • > Lacrimal nerve
  • > Frontal Nerve

Supplies general sensory info to most of the orbit

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16
Q

How is the maxillary nerve related to the orbit?

A

It supplies sensory information to the floor of the orbit and the eyelids.

It passes through the inferior orbital canal into the orbit and out the infraorbital foramen as the infraorbital nerve

17
Q

How does the ophthalmic artery reach the orbit?

A

Through the optic foramen alongside the optic nerve

It wraps around the optic nerve

18
Q

What branch of the ophthalmic artery supplies the retina

A

Central Retinal Art
Travels within the optic nerve
Supplies inner retinal layers (remember outer layers are supplied by the choroid)

19
Q

What arteries supply the choroid?

A

Short posterior ciliary arteries (branches of the ophthalmic)

20
Q

What arteries supply the ciliary body and iris (and anterior choroid)?

A

Long Posterior Ciliary Arteries

21
Q

Summary of ophthalmic artery and branches:

A

Branches from ICA and enters orbit via the Optic Foramen

1) Central Retinal Art –> Travels within optic nerve –> Inner Retinal layers

2) Posterior Ciliary Arteries:
short - Choroid
Long - Iris/ciliary body/ant choroid

3) Ant/Post Ethmoidal Arteries -> Nasal cavity/septum superiorly
4) Muscular Arteries

22
Q

What can we see using an ophthalmoscope and how do we divide it up

A

The optic disc (a physiological blind spot) and coming off it the central retinal artery and vein

The fovea centralis

We divide the image into 4 quadrants with the intersection on the optic disc:

  • Inferonasal
  • Superonasal
  • Superotemporal
  • Inferotemporal
23
Q

What veins drain the eye and to where?

A

Sup & Inf Ophthalmic veins drain to the cavernous sinus
Superior ophthalmic vein via the sup orbital fissure
Inferior ophthalmic vein via the inferior orbital fissure

24
Q

What lines the intracranial venous sinuses?

A

Squamous epithelium (Endothelium)

25
Q

What nerves sit in the walls of the cavernous sinus?

A

Cr N 3,4,5,6 (2 sits just behind it)

Also the ICA passes through the sinus

26
Q

What action does the superior rectus carry out

A

elevation
intorsion
Abduction

27
Q

What action does the inferior rectus carry out

A

depression
extorsion
Adduction

28
Q

Superior oblique

A

Intorsion
abduction
depression

29
Q

inferior oblique

A

Extorsion
Abduction
Elevation

30
Q

Medial rectus

A

Abduction

31
Q

Lateral rectus

A

Adduction

32
Q

What is the ciliates muscle responsible for?

A

Accommodation of the eye via constriction of the ciliaris muscle

33
Q

What structure lie very close to the bony orbit?

A

Frontal, maxillary and Ethmoidal sinuses

34
Q

Which floors of the orbit are particularly weak?

A

The inferior and medial

35
Q

Length of the orbit and the eyeball?

A

Orbit: 40mm
eyeball: 25mm