week 1 instant anatomy tutorial (high yield facts)

Question 1

what is the function of the meibonian glands(tarsal glands)?

Answer 1

secrete lipids to preserve tears

Question 2

what is ptosis

Answer 2

dropping of eyelid down/too low

Question 3

what controls eye opening?

Answer 3

levator with Muller’s muscle

[Levator is controlled by the CNIII; Muller’s muscle is under sympathetic control]

Question 4

what controls eye closing?

Answer 4

orbicularis oculi
[Controlled by
the CN 7th nerve]

Question 5

muller’s muscle is innervated by what?

Answer 5

sympathetic innervation - fright and eyes go big (let in light)

Question 6

what are the signs of Horner’s syndrome (compromised sympathetics)

Answer 6

ptosis, miosis, anhydrosis, red/flushing

Question 7

where/what is the orbital septum?

Answer 7

lies just posterior to the orbicularis oculi muscle.

fibrous band to protect against infection becoming deep (and going to brain)

Question 8

what us the difference between orbital and preseptal cellulitis?

Answer 8

Orbital cellulitis is
an inflammation 
posterior to the septum 
and is sight threatening. 
(opposite =  preseptal 
cellulitis)	- kids usually admitted to be on the safe side

Question 9

infected eye cause by what? how to distinguish between the two causes

Answer 9

eyelid infection going backward or sinus infection coming forward.

nose problem and round rim of eye = sinus; extensive eye and face = eyelid

Question 10

the orbicularis oculi two parts and functions

Answer 10

The orbital part of the orbicualris oculi muscle closes the eye tightly. The palpebral part is involved in normal blinking.

Question 11

lacrimal gland two types of production

Answer 11

basal

reflex(irritation, emotional…)

Question 12

some keys facts of the tear film produced by lacrimal gland

Answer 12

Has antibacterial properties due to the action of lysozyme

Basal and reflex secretion

Has a pH of around 7.6

An intact trigeminal nerve is 
required for reflex 
tear production (EG: diabetic neuropathy stops this leading to dry eyes)

Question 13

film tear nerves (sensation and motor)

Answer 13

Sensation = 5th nerve – tells the brain that the eye needs tears
Motor = 7th nerve parasympathetic fibres

Question 14

what are the two types of conjunctiva?

Answer 14

The inner surface of the eyelids is covered by the palpebral conjunctiva. The eyeball is lined by the bulbar conjunctiva.

Question 15

what is the difference between the two types of conjunctiva

Answer 15

The palpebral conjunctiva is more vascular than the bulbar
Follicles and papillae can be seen on the palpebral conjunctiva
Contains goblet cells which secrete part of the tear film

Question 16

what causes papillae to be seen on palpebral conjunctiva?

Answer 16

allergy (hay fever, wearing contact lenses too long)

Question 17

what causes follicles to be seen on palpebral conjunctiva?

Answer 17

adenovirus conjunctivitis (due to swimming/URTI), feel LN to decide cause (LN present=adenovirus=not dangerous)

Question 18

cornea structure (5 layers)

Answer 18

epithelium (turnover every 48Hrs, symptoms fine in corneal abrasion), bowman’s membrane, storma (largest part), descemet’s membrane, endothelium (lose as get older, not replied) -[sup to deep]

Question 19

Keratoconus

Answer 19

thinning of cornea

Question 20

what happens to the lens with age? lens structure?

Answer 20

loses elasticity and so become bifocal/verifocal glasses dependant (poor regeneration properties)

The outermost part of the lens is known as the cortex, inner part is the nucleus

Question 21

what attaches the lens to the ciliary body? how does this allow function?

Answer 21

the zonules.

A decrease in tension of the zonular fibres allows for near focussing

Question 22

if you want to see something closer, what happens to the lens?

Answer 22

becomes shorter/fatter

Question 23

what 3 parts does the Uvea contain?

Answer 23

iris, ciliary body, choroid

Question 24

uvea function

Answer 24

blood supply/nutrition

pigment (to capture light and prevent light scatter)

Question 25

how is aqueous humour produced?

Answer 25

Aqueous humour is produced by filtration of blood at the ciliary processes but is also actively secreted

Question 26

aqueous humour route

Answer 26

Aqueous humour flows from posterior chamber to the anterior chamber and drains into the canal of Schlemm and Trabecular meshwork

Question 27

IOP causes and results in?

Answer 27

inc secretion and reduced clearance glacoma, optic nerve damage

Question 28

WBCs in aqueous (foggy/flare) means what?

Answer 28

uveitis (inflammation lead to discharge of WBC), give glucocorticoids (in eye/oral)

Question 29

pain + photophobia + red eye

Answer 29

uveitis, give glucocorticoids (in eye/oral)

Question 30

describe the pupillary reflex

Answer 30

light → optic nerve →crossover →pre-tectal nucleus →crossover and to Edinger-Westphal nucleus = why both pupils contract [slide 25]

Question 31

sympathetic pathway

Answer 31

hypothalmus, contorls autonomic pathways, symps in C-spine, superior cervical ganglion, travels along arterils

Question 32

potential interruption to the sympathetic pathway (causes horner's)

Answer 32

pancoast tumour at superior cervical ganglion carotid dissection along arteries (painful horner's)

Question 33

what is the accommodation reflex? what is the stimulus?

Answer 33

``` helps focus (lessens as become older) The stimulus for the reflex is a blurred image on the retina ```

Question 34

the third nerve (CNIII)

Answer 34

Oculomotor nerve controls all IO muscles except LR and SO - plays role in accommodation reflex

Question 35

In a complete third nerve palsy what occurs? how can complete third nerve palsy occur?

Answer 35

the eye is positioned down and out with ptosis

Question 36

how can complete third nerve palsy occur?

Answer 36

poor controlled diabetes/hypertension can cause, improves over 6-8 weeks non-resloving: 3rd nerve lies close to posterior communicating artery and is vulnerable to aneurysms there, do scan and surgery

Question 37

what is the 4th CN? where does it arise from?

Answer 37

The trochlear nerve is unique in that it arises from the dorsal aspect of the brainstem and crosses over

Question 38

where does CN IV enter the eye? what does it do?

Answer 38

via the superior orbital fissure. supplies superior oblique muscle

Question 39

CN V arises from where?

Answer 39

The trigeminal nerve arises from 3 nuclei in the midbrain and medulla. [ophthalmic division most important for ophthalmology]

Question 40

the ophthalmic division (CN V1) conveys does what?

Answer 40

supplies the tip of the nose (nasociliary branch) conveys the afferent arm of the corneal reflex

Question 41

what is Hutchison's sign?

Answer 41

redness of tip of nose due to singles (VZV), tip of nose is end of CN V1 therefore check eye involvement.

Question 42

CN VI name, function?

Answer 42

abducens nerve, supplies the motor innervation to lateral rectus

Question 43

where does the 6th nerve pass through?

Answer 43

the middle of the cavernous sinus (not the wall)

Question 44

what causes Abducens nerve palsies?

Answer 44

raised intracranial pressure stretches the nerve | The 6th nerve arises from its nucleus in the pons

Question 45

where do the 4 rectus eye muscle arise from?

Answer 45

common tendinous ring

Question 46

painful eye movements?

Answer 46

optic neuritis, think MS. because the optic nerve sheath is attached to the common tendinous ring

Question 47

which is the strongest and thickest of the recti?

Answer 47

medial

Question 48

what does a blowout # typically entrap?

Answer 48

the inferior rectus

Question 49

where is the high density area that most cones are found

Answer 49

fovea

Question 50

what are the rods/cones embedded in?

Answer 50

cuboidal epithelium

Question 51

what gives rise to the optic nerve?

Answer 51

The ganglion cells

Question 52

why must light pass though the ganglion cells before hitting the cones/rods?

Answer 52

bc the retina is inverted (posterior = photoreceptors, then ganglions, the forming optic nerve, then arteries/veins.)

Question 53

what is the optic nerve encase in?

Answer 53

the meninges

Question 54

where is the blind spot (optic nerve) located?

Answer 54

15 degrees temporally in the visual field

Question 55

which fibres decussate at the optic chasm and which don't?

Answer 55

nasal fibres decussate, while temporal fibres continue ipsilaterally.

Question 56

learn the optic pathway and what interruptions cause which problem.

Answer 56

slide 38

Question 57

blood supply to the eye?

Answer 57

ophthalmic artery is a branch of the internal carotid (end artery = 90mins to save or blind)

Question 58

when looking at fundoscopy how can you tell which eye it is?

Answer 58

optic disc on left = left eye.

Question 59

what to look for on fundoscopy?

Answer 59

colour, contour, cup

Question 60

what will optic neuritis/raised ICP do on fundoscopy?

Answer 60

Fluffy contour of optic disc

Question 61

what colour should optic disc be on fundoscopy?

Answer 61

pink, white = bad (ischema?)

Question 62

how to tell difference between artery and vein on fundoscopy?

Answer 62

``` artery = elastic/muscly vein = dark red ``` Retinal veins appear thicker than retinal arteries (on fundoscopy) as arteries have a muscular tunic

Question 63

Central Retinal Arterial Occlusion occurs, what to do? what is seen on fundoscopy?

Answer 63

refer to stroke unit (high risk of stroke). blindness unless <90mins red dot (macula as has own blood supply) while rest is white with oedema

Question 64

venous drainage of the eye

Answer 64

The superior ophthalmic vein leaves the eye via the Superior orbital fissure The vein drains into the cavernous sinus Retinal vein occlusions are very common

Question 65

sensory supply of the eye

Answer 65

The long and short ciliary nerves become part of the nasociliary nerve of the trigeminal; The cornea has a rich supply of free nerve endings however, the retina has receptors for light only

Question 66

flashes of light, bloody floaters, (no pain)

Answer 66

retinal detachment - macula on and off = different prognosis/urgency of treatment

Question 67

risk factors for retinal detachment

Answer 67

trauma, previous surgery/detachment, being short sighted (marina's = spontaneous)

Question 68

what is most vulnerable in trauma

Answer 68

The inferior wall of the orbit. | medial wall thinnest

Question 69

what passes through the supraorbital notch

Answer 69

The supraorbital nerve and vessels (can be damaged on trauma) - pain/pressure point of GCS

Question 70

what do patients with blowout # commonly complain of?

Answer 70

pain on upgaze