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HNN > Session 8 > Flashcards

Session 8 Flashcards

1
Q

Clinical application of anatomy of orbit

A

Orbital blow out fractures

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2
Q

Clinical application of anatomy of eyelids

A

Styles, meibomian cysts, blepharitis

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3
Q

Clinical application of anatomy of orbital septum

A

Pre-septal, post-septal, cellulitis

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4
Q

Clinical application of anatomy of lacrimal apparatus

A

Blockage

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5
Q

Clinical application of anatomy of eye ball

A

Acute red eye, CRAO, glaucoma

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6
Q

Clinical application of anatomy of how we see

A

Reduced visual acuity

Refractive vs non refractive

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7
Q

Description of shape of orbital cavity

A

Pyramidal shaped with apex pointing posteriorly

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8
Q

Describe walls of orbital cavity

A

4 bony walls
Base of pyramid faces anteriorly- tough orbital rim
Ethmoid bone = medial wall contribution
Maxillary bone = floor contribution

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9
Q

What are the weakest parts of the orbital cavity

A

Floor of orbit (maxillary bone) and medial wall (ethmoid bone)

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10
Q

Anatomical relations of the orbit

A
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11
Q

Anatomical relations of the orbit has implications for

A

Orbital surgery
Spread of infection (e.g. acute sinusitis involving ethmoid sinus)
Orbital trauma

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12
Q

What causes orbital blowout fracture

A

Sudden increase in intra-orbital pressure from trauma to the eye/orbit (e.g. from retropulsion of eye ball by fist or ball)

Fractures floor of orbit (maxilla)

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13
Q

What can happen in orbital blowout fracture

A
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14
Q

Management of orbital blowout fracture

A
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15
Q

Part of the ethmoid forming the medial wall of the orbit is known as the

A

Lamina papyracea- paper thin

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16
Q

What can cause orbital cellulitis

A

Air cells become infected (acute sinusitis), infection can break through thin lamina papyracea and track into orbit

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17
Q

Holes at apex of orbit

A

Optic canal- optic nerve and ophthalmic artery

Superior orbital fissure- CNs III, IV, VI and Va, superior ophthalmic vein

Inferior orbital fissure- infraorbital nerve (branch of Vb), inferior ophthalmic vein

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18
Q

What is more likely to fracture in orbital fracture, floor or medial wall

A

Floor

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19
Q

Superior ophthalmic vein communicates with

A

Cavernous sinus

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20
Q

Inferior ophthalmic vein communicate with

A

Pterygoid venous plexus

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21
Q

Opthalmic artery has several branches including the

A

Central retinal artery

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22
Q

Main artery supplying eye and structures

A

Opthalmic artery

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23
Q

Main arterial supply to orbit and eye

A

Opthalmic artery (branch of ICA), and its branches including central retinal artery

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24
Q

Main venous drainage of orbit and eye

A

Opthalmic veins (superior and inferior), connections with cavernous sinus, pterygoid plexus and facial vein

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25
Q

Retina is blood supplied by

A

Central retinal artery and underlying choroid layer

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26
Q

Ciliary arteries do what

A

Feed extensive capillary bed within choroid layer

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27
Q

Retina requires what

A

Both circulations to function properly:

Central retinal artery and Ciliary arteries from underlying choroid layer

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28
Q

Outer protective layer of eyeball comprises of

A

Tough fibrous sclera, continuous anteriorly as the transparent cornea

Provides attachment for extra-ocular muscles, gives shape to eyeball, continuous with dural sheath covering optic nerve at back of eye

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29
Q

What covers over the sclera

A

A thin transparent layer of cells called the conjuctaivae

Extends up to edge of cornea (limbus) anteriorly and reflects onto inner surface of eyelids posteriorly

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30
Q

Central retinal artery runs

A

In middle of optic nerve

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31
Q

What runs though the conjunctivae

A

Blood vessels

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32
Q

Layer of eyeball

A

Retina, choroid, sclera

Outer, middle, inner

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33
Q

What happens in conjunctivitis

A

Conjunctivae become inflamed
Blood vessels dilate and eye appears red
Usually viral aetiology
Highly contagious

Patients report uncomfortable and gritty eye with accompanying tearing

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34
Q

Treatment of conjunctivitis

A

Reassurance, hygiene advice, short course of topical chloramphenicol eye drops (reduces risk of secondary bacterial infection)

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35
Q

What can cause conjunctions in neonatal period

A

Infective organism such as chlamydia picked up from mothers vaginal mucous

Need systematic antibiotics- erythromycin

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36
Q

Eyelids consist of

A

Skin, subcutaneous tissue, muscles, tarsal plate

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37
Q

Key muscles running within eyelid

A

Orbicularis oculi (closes eyelid, facial nerve)

Levator palpebrae superioris (retracts eyelid, occulomotor and some sympathetic)

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38
Q

Glands within eye lids

A

Meibomian glands within tarsal plate- modified sebaceous, lipid layer of tear film, prevent tear evaporation and spillage over lid

Glands associated with lash follicle- sebaceous oily substance

Blockage of a gland can cause a lump within the eyelid

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39
Q

What is a Meibomian cyst

A
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40
Q

What is a style

A
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41
Q

What is blepharitis

A
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42
Q

Features of the middle layer of the eyeball

A

Richer vascular area
Includes choroid
Continues anteriorly as the ciliary body and Iris

ciliary body = vascular and muscular (ciliary process and muscle) connects choroid with iris

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43
Q

What is a subconjunctival haemorrhage

A

Can cause a red eye

One of the small conjunctival vessels ruptures often spontaneously, blood visible under transparent conjunctival layer, not painful, slowly resolve

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44
Q

What is the orbital septum

A

Thin fibrous sheet originating from orbital rim

Separates intra-orbital contents from muscle and subcutaneous tissue of eyelid

Barrier against infection spreading from superficial eyelid region (pre septal) into orbital cavity (post septal)

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45
Q

Infection involving superficial tissues is called

A

Pre-septal (periorbital) cellulitis

Anterior to septum

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46
Q

Infection involving tissues within orbit is called

A

Post-septal cellulitis

Posterior to septum

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47
Q

Features of periorbital (pre-septal) cellulitis

A

Secondary to superficial infections (bites, wounds)
Confined to tissues superficial to orbital septum (and tarsal plates)
Painful
Eye movements and vision remains unaffected

48
Q

Features of orbital post septal cellulitis

A

Spread of infection from paranasal air sinus

Proptosis/exopthalmous

Reduced and or painful eye movements, reduced visual acuity

49
Q

Why is post septal orbital cellulitis so dangerous

A

Orbital veins drain to cavernous sinus and pterygoid venous plexus

Potential route for infection to spread intracranially- cavernous sinus thrombosis, meningitis

50
Q

What suggests serious underlying cause of red eye

A

Presence of acute pain e.g. uveitis (inflammation of choroid layer)

51
Q

What is Uveitis

A

Inflammation of choroid layer

Red, painful eye, worse when trying to focus or look at bright lights

Associated with autoimmune conditions such as ankylosing spondylitis, IBS

Need urgent referral to ophthalmology for treatment (corticosteroids)

52
Q

Features of the inner layer of the eye

A

Retina
Photosensitive and non-photosensitive parts

Cells either part of neurosensory layer or pigmented epithelial layer

53
Q

Features of pigmented layer of retina

A

Lies between choroid and neurosensory layer, cells contain melanin

Melanin helps absorb scattered light that has passed into eye, reducing reflection and allowing us to focus images

54
Q

Contents of orbital Cavity

A

Nerves, blood vessels, Fat, lacrimal apparatus, eyeball, extra-ocular muscles

55
Q

Tear film consists of

A

3 layer- oily, water, mucus

Oily: Meibomian glands
Water: lacrimal gland
Mucus: goblet cells in conjunctiva

56
Q

What does blinking do

A

Distribute tear film across surface of eye- rinsing and lubricating conjunctivae and cornea

57
Q

What are lacrimal apparatus

A

Series of structures that collect and drain tear fluid

Obstruction to drainage causes epiphyseal (overflow of tears over lower eyelid)

Obstruction caused by infection,injury or stenosis

58
Q

What makes up lacrimal apparatus

A
59
Q

Eyeball is maintained in position by

A

Suspensory ligament, extra-ocular muscles, orbital fat

60
Q

Features of neurosensory layer of retina

A

Senses light and is where photoreceptors (rods and cones) are found

Cones are responsible for high visual acuity and colour vision and many are concentrated in macula

61
Q

Features of macula

A

Macula visible on fundoscopy as slightly darker, lateral to optic disc. Centre of macula called fovea, only contains cones

62
Q

What causes colour blindness

A

Red green and blue sensitive cones respond to different wavelengths

Absence or dysfunction of one of these leads to colour blindness, inherited condition that affects males more frequently than females

63
Q

What are rods responsible for

A

Vision in low intensity light, do not discern colours

Some towards central retina but more abundant in peripheral parts

64
Q

What do photoreceptors do

A

Convert light energy into electrical impulses which reach optic disc

Optic disc represents the accumulation of retinal axons that leave the eye as the optic nerve- devoid of photoreceptors

Optic disc is blind spot

65
Q

Overview of 3 layers of eye

A
66
Q

What is responsible for central vision

A

Macula (and fovea): point of highest acuity vision

Thinnest part of retinal layer, lots of cones

67
Q

Chamber of the eye

A

3- anterior, posterior and vitreous

Vitreous = transparent, jelly-like vitreous humour

Anterior and posterior = transparent liquid called aqueous humour

68
Q

What is anterior chamber

A

Space between the cornea and iris, communicated with posterior chamber through pupil

69
Q

What is posterior chamber

A

Space between iris and lens. Ciliary body and processes are found, which secrete aqueous humour filling both anterior and posterior chamber

70
Q

Aqueous humour is important for

A

Supporting shape of eyeball by pressure it exerts, nourishment of lens and cornea as they are avascular

71
Q

The aqueous humour drains through the

A

Irido-corneal angle into canal of Schlemm via trabecular meshwork and subsequently back in venous system

72
Q

Sudden painless loss of sight in one eye developing over seconds can be caused by

A

Central retinal artery occlusion

Pale retina (ischeamia), cherry red spot = macula

73
Q

Why do you get cherry red spot

A

Underlying choroidal layer blood supply un affected so remains perfused

Macular is thinnest part so underlying choroid accentuated due to surrounding pallor of ischemic retina

74
Q

Production and drainage of aqueous humour

A
75
Q

What is a glaucoma

A

Optic nerve damage secondary to raised intraocular pressure

76
Q

2 types of glaucoma

A
77
Q

Features of open angle glaucoma

A

Develops painlessly and insidiously over time
IOP can be determined using tonometry. Signs such as cupping of disc and visual field loss (especially peripheral) may be present

78
Q

Treatment of open angle glaucoma

A

Topical medications (eye drops) That reduce production and increase drainage of aqueous humour e.g. Beta blockers such as Timolol

This reduces IOP, surgery may be required (trabeculectomy)

79
Q

Presentation in closed angle glaucoma

A

Sudden onset of a painful red eye, blurred vision or halos around objects (due to corneal oedema)

Fixed or sluggish, semi-dilated often irregular, oval shaped pupil

Nausea and vomiting

80
Q

Clinical examination on closed angle glaucoma

A

Eye is hard and tender to palpate though upper eyelid

Emergency requiring rapid recognition and management, irreversible sight loss can occur within a few hours

81
Q

Management of closed angle glaucoma

A

Diuretics (acetazolamide), muscarinic eye drops (pilocarpine) and strong analgesia

Pupillary constriction helps open irido-corneal angle to improve route of drainage and reduce IOP

Surgery may be needed to make a hole in iris (iridotomy) with a laser or surgically, aqueous humour can flow from posterior to anterior chamber

82
Q

Who is most at risk of closed angle glaucoma

A

Long sighted Middle Aged or elderly people with shallow anterior chambres

83
Q

Features of the iris

A

Lies just anteriorly to lens

Thin contractile diaphragm, with a central aperture (pupil) for transmitting of light

Iris gives colour to eye, sphincter and dilator pupillae form the iris and control size of pupil

Autonomic nervous system

84
Q

Features of lens

A

Posterior to iris

Transparent biconvex structure enclosed in a capsule

Without nerve innervation or blood supply, receives nutrients entirely from aqueous humour

Edges of the lens capsule attached to ciliary body by Suspensory ligament

85
Q

What are cataracts

A

As we age, degradation of the proteins in the lens cause it to become clouded and less transparent

Cause visual impairment but treated with surgery

86
Q

Contraction of the ciliary muscle (within ciliary body) are under the influence of the

A

Parasympathetic nervous system, alters tension in Suspensory ligaments

Allows for changes in shape of lens and its refractive power

At rest, ciliary muscle is relaxed and Suspensory ligaments are pulled taut, keeping lens flat

87
Q

Important things to be able to see

A
88
Q

What is refraction

A

The change in direction of light on passing through boundary of 2 different mediums

89
Q

What is the accommodation reflex

A
90
Q

Over view of rods and cones

A
91
Q

Action potentials are propagated via

A

Retinal ganglion cells (RGCs)

92
Q

Causes of decreased visual acuity

A
93
Q

Most common cause of adult blindness in UK

A

Age related macular degeneration

94
Q

How to check for decreased visual acuity due to reduced transparency of structures

A

Check for red reflex using ophthalmoscope- absent suggests light prevented from reaching retina and reflecting back e.g. cataracts

95
Q

Most concerning cause of decreased visual acuity

A

Non refractive- retinal or optic nerve problem

96
Q

Features of refractive cause of decreased visual acuity

A

Abnormal corneal surface
Inability of lens to change shape
Size of eyeball

97
Q

How to tell if decreased visual acuity is from refractive error or not

A
98
Q

What does pin hole testing do

A
99
Q

Lacrimal fluid from the lacrimal gland enters the

A

Conjunctival sac through lacrimal ducts and passes into lacrimal lake at medial angle of eye

Fluid drains into lacrimal sac (S) before passing into nasal cavity via nasolacrimal duct (N)

100
Q

What can occur if dirt or particles damage the cornea

A

Corneal abrasions and ulceration

Fortunately the outer epithelial layer of the cornea is constantly undergoing mitosis, so easily regenerates if damaged

101
Q

Pathology interrupting the sympathetic innervation the eye leads to a

A

Partial ptosis

102
Q

Which muscles control movements of the eyeball

A

Four Recti and 2 oblique

Most innervated by occulomotor

Lateral rectus and superior oblique innervated by Abducens and trochlear nerve respectively

103
Q

4 recti muscles all arise from a

A

Common tendinous ring- fibrous cuff that surrounds the optic canal

104
Q

How do the oblique muscles work with recti

A

Arise from bony walls of orbit and work synergistically with recti

105
Q

What does LR6SO4 mean

A

LR supplied by Abducens, SO supplied by Trochlear nerve

106
Q

What does asking the patient to follow a moving finger do

A

Text extra-ocular muscles

Allows the function of CN III, IV, and VI to be determined

107
Q

Testing extra-ocular muscles

A
108
Q

Why binocular vision

A

Allows for wider field of vision and depth perception, visual axis of both yes need to be aligned and conjugate eye movement is required

Two images that reach cortex are fused so perceived as one

109
Q

Misalignment of visual axes causes

A

Diplopia

110
Q

Muscles that move eye ball origin and attachment

A

Origin - apex of orbit
Attach- sclera

111
Q

Extraocular muscles run in line with

A

Axis of orbit

Therefore some muscles attach at oblique angle

Confers several actions of movement on glove

112
Q

Action of superior rectus muscle

A
113
Q

Action of inferior rectus muscle

A
114
Q

Action of superior oblique muscle

A
115
Q

Action of inferior oblique muscle

A
116
Q

Midline elevation and depression combine actions of

A
117
Q

What is Ocular misalignment- Strabismus

A

HNN (19 decks)

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