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My Ophthalmology > Anatomy > Flashcards

Anatomy Flashcards

1
Q

What is the punctum?

A

the hole where the tears go down

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2
Q

What does the conjunctiva cover?

A
  • the sclera but not the cornea

- forms a valley called the conjunctival fornix

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3
Q

What are the layers of the eye?

A
  • Fibrous outer layer:
    ..Sclera- muscle attachment
    ..Cornea
  • Uvea vascular layer:
    ..Iris- pupil diameter
    ..Ciliary body- control iris, shape of lens and secretion of aqueous humour
    ..Choroid- this is highly vascular
  • Retina photosensitive inner layer:
    ..The posterior part is the visual part
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4
Q

What is the limbus?

A

corneoscleral junction

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5
Q

What are the eye segments?

A
  • Anterior: this has an anterior chamber (between cornea and iris) and a posterior chamber (between iris and suspensory ligaments)
  • Posterior: contains vitreous body with vitreous humour, floaters are here
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6
Q

What is the iridocorneal angle?

A

the angle between the cornea and the iris

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7
Q

What is the path of aqueous fluid?

A
  • secreted by ciliary processes
  • circulates and nourishes lens
  • passes through pupils and nourishes cornea
  • drains into the scleral venous sinus at the iridocroneal angle
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8
Q

What is the arterial supply to the eye?

A
  • ophthalmic artery is a branch of the internal carotid artery
  • central artery of the retina runs within the optic nerve
  • ciliary arteries supply the choroid layer
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9
Q

What is the venous drainage from the eye?

A
  • superior and inferior veins join and drain into the cavernous sinus
  • some is also through the pterygoid plexus
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10
Q

What are the features of the optic disc?

A
  • where the optic nerve is formed
  • point of entry for artery and blood vessels
  • the blind spot
  • is always on the nasal side
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11
Q

What is the macula and the fovea?

A

the macula is where the greatest density of cones is and the fovea is at the centre of this

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12
Q

What does light have to go through to get to the photoreceptors?

A
  • retinal arteries and veins
  • through ganglion cells
  • through axons
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13
Q

Where is light from objects in the lower visual field processed?

A

by the upper part of the primary visual cortex

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14
Q

What are the planes and movements of the eye?

A
  • Vertical (adduction or abduction)
  • Transverse (elevation or depression)
  • Anteroposterior axis (the superior pole of the eyeball goes laterally or medially- this is more of a rotation)
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15
Q

What are the extra ocular muscles?

A
  • superior rectus
  • medial rectus (just primary movement)
  • inferior rectus
  • lateral rectus (just primary movement)
  • superior oblique
  • inferior oblique
  • levator palpebrae (eyelid)
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16
Q

How do you clinically test an extra ocular muscle?

A
  • involves isolation of the muscles

- needs to line up with the angle of the pupil

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17
Q

What is the movement of the lateral and medial rectus?

A
  • Lateral rectus: this can only abduct the eyeball, CNVI, brings line of gaze into same plane as superior rectus and inferior rectus
  • Medial rectus: can only adduct the eyeball, this brings the line of gaze into the same plane as the inferior and superior oblique
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18
Q

What is the movement of the superior and inferior rectus?

A
  • Superior rectus: when in abduction, SR can only elevate, CNIII
  • Inferior rectus: when in abduction, IR can only depress , CNIII
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19
Q

What are the movements of the superior and inferior obliques?

A
  • Inferior oblique: when in adduction, this can only elevate, CNIII
  • Superior oblique: when in adduction, this can only depress, CNIV
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20
Q

What does pure elevation involve?

A
  • superior rectus and inferior oblique
  • elevates eyes synergistically
  • antagonists as rotators
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21
Q

What does pure depression involve?

A
  • superior oblique and inferior rectus
  • synergistically depresses
  • antagonists as adductors/abductors
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22
Q

What is the sensory innervation to the face?

A
  • Ophthalmic: upper eyelid, cornea, conjunctiva, down to tip of nose
  • Maxillary: skin of the lower lid, skin over the maxilla
  • Mandibular: skin over mandible and TMJ, except angle of mandible
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23
Q

What is involved in the blink reflex?

A
  • somatic reflex
  • CNV1 is sensory to cornea which then goes to the trigeminal ganglion this goes to CNV and then to the pons
  • CNVII is the motor part of this reflex to the orbicularis oculi
  • opening eye again is mainly levator palpebrae superioris
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24
Q

What is the vestibulo-ocular reflex?

A

eyes automatically moving when the head moves

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25
Q

What is the oculocardiac reflex?

A

pressure on the eye, there is bradycardia to lower the BP

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26
Q

What is involved in the wide eye reflex in fight or flight?

A
  • more light into eye and make pupil bigger
  • focus on far away objects
  • levator palpebrae superioris
  • Mueller’s muscle (sympathetic of opening eyes wider than normal)
  • fibres go to superior cervical ganglion, then internal carotid nerve, then plexus and the ophthalmic artery then branches
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27
Q

What is involved in constriction of the pupil?

A
  • Parasympathetics constrict the pupils
  • A miotic pupil is a non-physiologically constricted pupil eg Horner’s syndrome
  • Sphincter pupillae fibres encircle pupil when it contracts
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28
Q

What is involved in the dilation of the pupil?

A
  • Dilation is sympathetic innervation
  • Mydriatic drug causes this
  • Dilator pupillae fibres pull the sphincter apart to make the pupil wider
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29
Q

What is involves in the pupillary light reflex?

A
  • afferent is ipsilateral CNII
  • four neurone motor chain
  • efferent is bilateral CNIII
  • this is a consensual reflex
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30
Q

What is the accommodation reflex?

A
  • actual lens
  • spherical lens=near vision, parasympathetics, relaxed zonules, contract ciliary muscle, more reflective
  • flat lens=far vision, no parasympathetics, ligament tightens
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31
Q

What happens when you bring your finger closer to your eyes?

A
  • Bilateral pupillary constriction
  • Bilateral convergence of both eyes towards midline
  • Bilateral relaxation of the lens
  • This is all CN3 oculomotor
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32
Q

What are the various lacrimation reflexes?

A
  • Basal tears: all the time, lubricate and hydrate the eye, nourish the cornea
  • Reflex tears: mechanical or chemical stimulation, afferent is CNV1, efferent is CNVII to the lacrimal gland which is via the pterygopalatine ganglion
  • Emotional tears: parasympathetic innervation
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33
Q

How do the parasympathetic to the lacrimal gland work?

A
  • branch of facial
  • parasympathetic which is greater petrosal nerve
  • rides on trigeminal
  • to lacrimal gland
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34
Q

What is wrong if white sclera can be seen above the iris?

A

globes could be pushed forward eg in hyperthyroidism Graves’ disease

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35
Q

What are the main three symptoms of Horner’s syndrome?

A

ptosis (droopy eyelid), only sweating on one side of the face and constricted pupil

36
Q

What is Bell’s palsy?

A

you can’t close your eyelid which is a CNVII palsy

37
Q

What is included in uvea?

A

the iris, ciliary body and choroid so uveitis affects at least one of these

38
Q

What happens in the brain with a light reflex?

A

the ipsilateral pretectal nucleus speaks to bilateral Edinger-Westphal nuclei so there is a consensual reflex

39
Q

What is involved in the Relevant afferent pupillary defect?

A
  • optic nerve problem on one side so the pupil constricts less than normal
  • swinging light test
    • shine in affected eye and both pupils will constrict
    • quick shine in other eye and don’t allow for dilation
  • back to first eye and there will be an abnormal dilation in response to light (as the optic nerve is working less)
40
Q

What is the explanation for upper and lower visual field loss?

A
  • neurons in lower eye stay down in nerve etc
  • upper bit goes straight back as it is not blocked by ventricle = parietal lobe
  • lower bit is so comes front and round = temporal lobe
41
Q

Where is the issue in a quadrantanopia?

A

in the optic radiations which are after the geniculate ganglia

42
Q

What are the three orbital plates?

A

frontal, ethmoid, maxillary

last two are very thin so can fracture

43
Q

What goes through the superior orbital fissure?

A

CNs 3,4 and 6

44
Q

What is the supraorbital notch and the infraorbital foramen for?

A
  • supraorbital neurovascular bundle (CNV1)

- infraorbital neurovascular bundle

45
Q

What is a blow out fracture?

A

when the pressure or force is transferred and the thin bones at the back of the eye can fracture
fractures tend to be at sutures

46
Q

Where do fractures in the eye tend to be?

A

fractures tend to be at sutures

47
Q

What are the inner and outer parts of the superficial orbiculares oris?

A 
inner = palpebral part
outer = orbital part
48
Q

What is in the tarsi to stop tears overflowing?

A

glands to secrete lipids which line the eyelid to stop tears overflowing when they are produced normally

49
Q

Where does the nasolacrimal duct empty?

A

into the inferior nasal meatus so when crying, the nose can run

50
Q

What does the trochlea do?

A

causes the superior oblique muscle to change direction

51
Q

Where do the rectus muscles all attach?

A

annulus ring

52
Q

Where are the superior and inferior oblique muscles from?

A

Superior oblique is from sphenoid bone

Inferior comes from orbital plate of maxillary bone

53
Q

Where does the LPS muscle come from?

A

lesser wing of sphenoid bone

54
Q

What is the innervation of the extra ocular muscles?

A

LR6 SO4 AO3
Lateral rectus is CN6
Superior oblique is CN4
All other extraocular muscles are CN3

55
Q

What is the sympathetic supply to the eye?

A
  • exits at T1
  • moves up into the cervical region
  • reaches the superior cervical ganglion
  • synapses
  • postsynaptic axons then exit by internal and external carotid nerves
  • becomes a plexus around the internal carotid artery
56
Q

What is the parasympathetic supply to the eye?

A
  • leaves CNS by CN 3,7,9,10 or sacral nerves
  • ciliary ganglion (parasympathetic and is just anterior to optic canal, related to CN3)
  • only nerves that synapse in the ganglion are the parasympathetics from CN3
57
Q

What is the path of CN3?

A
  • comes off midbrain/pons junction
  • passes through cavernous sinus
  • enters cranial cavity at superior orbital fissure
  • divides into superior and inferior division (related to the ciliary ganglion)
58
Q

What are the meninges?

A
  • protective coverings that surround the brain and the spinal cord
  • they go through the foramen magnum
59
Q

What are the layers of the meninges?

A
  • Dura mater: hard covering, sensory nerve supply from CNV, has two layers which sometimes enclose the dural venous sinuses
  • Arachnoid mater: this has a spider-like appearance
  • Subarachnoid space: CSF and blood vessels are here
  • Pia mater: adheres to the brain and follows its contours
60
Q

Where can CSF be accessed form outside of the body?

A

L3/4 by a lumbar puncture without harming the spinal cord

61
Q

Where does subarachnoid space reach down to?

A

S2 (spinal cord goes down to around L2)

62
Q

What are the ventricles of the brain?

A
  • right lateral
  • left lateral ventricles
  • midline 3rd ventricle
  • 4th midline ventricle
63
Q

What is involved in the circulation of CSF?

A
  • Secreted by the choroid plexus in lateral ventricles and 3rd ventricle
  • Passes in right and left lateral ventricle
  • Then in the midline 3rd ventricle
  • Via cerebral aqueduct
  • To 4th ventricle into the subarachnoid space
  • Reabsorbed via the arachnoid granulations which are outpouchings
  • Into the dural venous sinuses
64
Q

What is raised ICP caused by?

A
  • chronic or acute
  • caused by an increased pressure in fluid around the brain and within the brain eg tumour, stroke, head injury, hydrocephalus and meningitis
65
Q

How does ICP increase?

A

the cranial cavity is closed off so if volume increases inside then pressure does too

66
Q

Where does the brain matter shift in increased ICP?

A

towards foramen magnum and superior orbital fissure etc

67
Q

What are the vision changes associated with increased ICP?

A
  • transient blurred vision
  • double vision
  • loss of vision
  • papilloemdema
  • pupillary changes
68
Q

What is special about the optic nerves?

A

they are actually CNS tracts so are covered by meninges (dura, arachnoid and pia)

69
Q

How does raised ICP cause papilloedema?

A

the raised ICP is transmitted along the subarachnoid space to the optic nerve and central artery + vein of the retina

70
Q

What are the symptoms of papiloedema?

A
  • Transient visual obscurations
  • Transient flickering
  • Blurring of vision
  • Constriction of the visual field
  • Decreased colour perception
71
Q

What can harm the oculomotor nerve?

A
  • PCA ANEURYSM (emergency until proven otherwise)
  • tumour
  • microvascular
  • MS
  • congenital
72
Q

What does damage to the oculomotor nerve cause?

A
  • paralysis of the extraocular muscles (except SO+LR) including sphincter papillae and levator palpebrae superioris
  • paralysis of parasympathetic innervation sphincter of the pupil
73
Q

What is the clinical sign of oculomotor nerve damage?

A
  • Down and Out (SO and LR working so right eye is down and out but left is straight)
  • ptosis
  • pupil dilation
74
Q

What are the septa of the cranial cavity?

A

folds of dura create septa
- falx cerebri = sagittal plane
- tentorium cerebelli = with an opening called the tentorium notch and makes a tent over the cerebellum
brain can herniate through these openings

75
Q

What is special about CNIV?

A

it has the longest intracranial nerve course of any cranial nerve

76
Q

What does damage to the trochlear nerve result in?

A
  • causes paralysis of the superior oblique muscle

- can present as head tilt as the incyclo-torsion is weak

77
Q

What is the clinical sign of CNIV damage?

A
  • the eye will be superior when looking to the right as there is unopposed movement of the inferior oblique
  • also diplopia when looking down
78
Q

What can damage CNVI and what will this result in?

A
  • causes are microvascular, raised ICP (bilateral as the brainstem is pushed down), tumour and congenital
  • paralysis of lateral rectus muscle so there is medial deviation of the eye
79
Q

What is special about CNVI?

A

the longest intradural course of all the CNs

80
Q

Where do the nerves run in relation to the cavernous sinus?

A
  • oculomotor and the trochlear run in the lateral wall in the dura
  • abducens runs through the cavernous sinus itself
81
Q

What are the symptoms of Horner’s syndrome?

A

sympathetic aren’t working

  • droopy eye as Mueller’s isn’t working
  • smaller pupil as the parasympathetics are unopposed
  • less sweating and more vasodilation
82
Q

What is the innervation of the cornea?

A

CNV1

83
Q

What are the causes of CNIV nerve palsy?

A
  • congenital
  • microvascular
  • tumour
  • bilateral from a head trauma (the nerves stretch in whiplash trauma so they stop working)
84
Q

How can you differentiate between a third nerve palsy due to aneurysm or microvascular issue?

A
  • aneurysm presses on the outside of the nerve so the pupil will be dilated as this is where these parasympathetic fibres are
  • microvascular will have a normal pupil as the problem won’t affect these outside fibres
85
Q

What happens with an inter-nuclear nerve problem?

A
  • involves eye moving together
  • caused by demyelinating lesion at the medial longitudinal fasiculus
  • causes impaired adduction on the affected side and an abducting nystagmus on the other side
86
Q

What is an supra-nuclear problem?

A

a problem with the inputs from higher centres in the brain which are telling the eyes to do something

87
Q

What is the afferent and efferent for the blink reflex?

A
  • afferent is 5 (nasociliary for corneal sensation)

- efferent is 7 for motor

My Ophthalmology (5 decks)

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