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Opthalmology > Anatomy > Flashcards

Anatomy Flashcards

(105 cards)

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1
Q

What makes us the uvea

A

Iris
Ciliary body
Choroid

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2
Q

Describe the function of rod cells

A

They are sensitive to low levels of light

Used mainly in night vision and peripheral vision

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3
Q

Describe the function of cone cells

A

Used for detailed and colour vision

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4
Q

What is the macula

A

Area of the retina with the highest concentration of cones

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5
Q

In a retinal image the thicker vessels are arteries - true or false

A

FALSE - they are veins

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6
Q

Name the extraocular muscles

A

Superior. inferior, lateral and medial rectus

Superior and inferior oblique

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7
Q

Which cranial nerves help with control of the eye

A 
2 - optic 
3 - oculomotor 
4- trochlear 
5- trigeminal 
6- abducens 
7 - facial
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8
Q

Which cranial nerves are involved in the blink reflex

A

Trigeminal - efferent part

Facial - afferent part

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9
Q

What is emmetropia

A

Normal vision

no refractive error in eye

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10
Q

What is hypermetropia

A

Long sightedness
The eyes are smaller than average so light is focussed behind the retina
Will need positive lenses to bring the light forward to retina

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11
Q

What is myopia

A

Short sightedness
Larger than average eyes so light is focussed in front of retina
Needs negative lenses to move focus back

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12
Q

What is presbyopia

A

lens gradually stiffens with age (usually starts around 40)

Can’t change shape to adjust focus

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13
Q

List the bones of the bony orbit

A 
Frontal bone 
Sphenoid bone 
Orbital plate of the ethmoid bone 
Zygomatic bone 
Maxilla 
Lacrimal
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14
Q

What passes through the optic canal

A

The optic nerve

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15
Q

What forms the edge of the bony orbit

A

The orbital rim and margin

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16
Q

Which bones of the bony orbit are most likely to fracture

A

Medial wall and inferior wall
(ethmoid, lacrimal)
Thin bones

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17
Q

What is an orbital blowout

A

Fracture of bones in the bony orbit - thinnest ones (medial wall and floor)
usually caused by a blow to the face
Can damage the infraorbital neurovascular bundle
Eyeball can be extruded

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18
Q

What passes through the infraorbital foramen

A

Infraorbital artery and nerve

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19
Q

What is the function of the eyelid

A

Protects the eyes

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20
Q

What do the eyelids contain

A

Tarsal plate - keeps shape
Glands - secrete lipids
Orbicularis oculi
LPS muscle

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21
Q

What is the function of the levator palpabri superiorus

A

Muscle that elevates the upper eyelid

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22
Q

What is ptosis

A

Closed eye

Indicator of a third nerve palsy

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23
Q

What is the function of the orbicularis occuli

A

Circular muscle that closes the eye when it contracts

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24
Q

What is the function of the conjunctiva

A

A defensive barrier that covers the eye

Reflects back from eye to inner surface of eyelid

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25
What is the cornea
The clear part of the eye that we look through | Responsible for refraction - lets light into the eye and focuses it onto the retina
26
What nerve supplies the lacrimal gland
CN VII - facial nerve | Parasympathetic supply
27
Describe how tears are formed
Produced in the lacrimal gland Blinking washes tears over eye They are pushed towards medial angle Drain into the lacrimal puncta then the canaliculi Will reach the lacrimal sac and eventually down the nasolacrimal duct and out the nose
28
What makes up the fibrous outer layer of the eye
sclera and cornea
29
What is the function of the iris
Controls diameter of pupil | It is a coloured muscle!
30
What is the function of the ciliary body
Controls iris, shape of lens and secretion of aqueous humour
31
What is the function of the choroid
Nutrition and gas exchange | Sits behind the retina
32
Where is the anterior segment
In front of the lens
33
Describe the divisions of the anterior segment
Anterior and posterior chamber Anterior is found between cornea and iris Posterior is found between iris and suspensory ligaments
34
What is contained in the anterior segment of the eye
Aqueous humour
35
Where is the posterior segment located
Behind the lens | 2/3 of the eye
36
What is contained in the posterior segment of the eye
Vitreous humour
37
What can an excess in aqueous fluid lead to
Glaucoma | Raises intraocular pressure
38
What secretes aqueous humour
Ciliary processes in the ciliary body
39
Describe the path of aqueous humour through the eye
Secreted in ciliary body Circulates in the posterior chamber to nourish lens Then passes through pupil to nourish cornea It is then reabsorbed into scleral venous sinus at the iridocorneal angle
40
What is the arterial supply to the eye
The ophthalmic arteries It is a branch of the internal carotid artery It branches itself into the ciliary arteries and the central artery of the retina
41
List the venous drainage of the eye
Superior ophthalmic vein Inferior ophthalmic Drain into the cavernous sinus Also drains anteriorly to the facial veins
42
What is the danger triangle
Area across the nose and upper lip | If there is an abscess here it can drain backwards into the cavernous sinus and lead to sinus thrombosis
43
What is the fovea
centre of the macula small depression area of most acute vision
44
What is the optic disc
Point of optic nerve formation Where blood vessels and nerve enter/exit Also has the blind spot
45
List the layers of the retina from posterior to anterior
Photoreceptors Ganglion cells Axons of the ganglion
46
Why is the optic disc the blind spot
There are no photoreceptors in the optic disc
47
Where is light from the right visual field processed
Left primary visual cortex | Opposite is true
48
Where is light from the lower visual field processed
Upper part of the primary visual cortex | Opposite is true
49
What does the superior orbital muscle pass through
A pulley | The trochlear
50
List the action of the recti eye muscles
lateral rectus – pulls eyeball laterally medial rectus – pulls eyeball medially superior rectus – up and in inferior rectus - down and in
51
List the actions of the oblique eye muscles
superior oblique – down and out | inferior oblique - up and out
52
List the innervation to the eye muscles
Lateral rectus - abducens nerve (CN6) Superior oblique - trochlear nerve (CN4) Rest of the muscles are CN3 (oculomotor)
53
What areas does CNV1 give sensory supply to
Upper eyelid Cornea Conjunctiva Skin of the root, bridge and tip of the nose
54
What areas does CNV2 give sensory supply to
Skin of the lower eyelid Skin over the maxilla Skin of the ala of the nose Skin/mucosa of the upper lip
55
What areas does CNV3 give sensory supply to
Skin over the mandible (except the angle) and temporomandibular joint
56
Describe the sensory limb of the blink reflex
Action potential conducted from cornea via CNV1 Then to the trigeminal ganglion along CNV To pons
57
Describe the motor limb of the blink reflex
Action potentials conducted CNVII | To eyelid part of orbicularis oculi
58
Describe the route of sympathetic axons
Thoracolumbar outflow Leaves brain and passes down spinal cord Exits spinal cord with T1-L2 Travel to the sympathetic chains Pass into the spinal nerves via anterior and posterior rami Pass into the splanchnic nerves to supply organs
59
Which nerves synapse in the superior cervical ganglion
Presynaptic sympathetic axons from the CNS Exit at T1 level and ascend in the sympathetic trunk Synapse in the ganglion
60
Describe the path of the post-synaptic neurons as they level the superior cervical ganglion
Enter the internal and external carotid nerves Pass onto surface of the internal and external carotid arteries Carried to the organs of the head with arteries
61
What carries sympathetic nerves into the orbit
The ophthalmic artery | Delivers fibres to the eye itself
62
How do parasympathetic axons leave the CNS
Via cranial nerves III, VII, IX and X And the sacral spinal nerves (Craniosacral outflow)
63
Which structures in the orbit are supplied by parasympathetic nerves
Eye | Lacrimal glands
64
Which parasympathetic nerve is responsible for changing the shape of the iris and lens
Fibres from CNIII | Oculomotor
65
Describe the path of the oculomotor nerve
Leaves brain between the midline and pons Passes through the cavernous sinus Exits via the superior orbital fissure Divides into superior and inferior division
66
What does the superior division of the oculomotor nerve supply
Somatic motor innervation to the superior rectus and levator palpebrae superioris
67
What does the inferior division of the oculomotor nerve supply
Somatic motor innervation to the medial and inferior rectus, the inferior oblique Parasympathetic axons to the ciliary ganglion
68
What are the functions of the ciliary nerves
Supply autonomic axons to the eye Controls diameter of iris and shape of lens Long nerves are sympathetic and somatic sensory (responsible for part of blink) Short ciliary nerves have both sympathetic and parasympathetic fibres
69
What occurs in the ciliary ganglion
Synapse of pre and post parasympathetic nerves
70
List the sympathetic effects on the eye
Open eyes wider Dilate pupils - get more light in Focus lens on far objects Emotional lacrimation - crying
71
What is the vestibulo-ocular reflex
Eyes move the opposite way to head movement | Stabilizes gaze during head movement
72
What is the oculocardiac reflex
Reflex bradycardia in response to tension on extraocular muscles or pressure on eye
73
List the effects of the parasympathetic nerves on the eye
Allows orbicularis oculi to work Constricts pupil - less light Focus on near objects Reflex lacrimation - wash away foreign bodies
74
Describe the levator palpebrae superioris
Contains smooth and skeletal muscle Supplied by oculomotor and sympathetic nerves Responsible for opening the eye
75
Why do our eyes open wide in the fight or flight response
Sympathetic nerves supplying the LPS are stimulated and the muscle contracts, opening the eye
76
What is a mydriatic pupil
One that is non-physiologically enlarged | Can be done with chemicals or drugs
77
What controls the diameter of the pupil
Dilator papillae fibres Arranged radially around the iris - dilate pupil Sphincter pupillae fibres constrict the pupil
78
What is a non-physiologically constricted pupil called
Miotic pupil | Seen in Horner's
79
What is a pinpoint pupil a sign of
Opiate drug use | Serious pathological sign
80
What is a fixed, dilated pupil a sign of
Serious pathology | Pathology of CN3
81
What is the direct light reflex
Constriction of pupil in the eye when light is shone into it
82
What is the consensual light reflex
Constriction of pupil when light is shone into the opposite eye
83
Which nerves are involved in the pupillary light reflex
Sensory info travels up the optic nerve CNS connection in midbrain Effector/motor part is by the oculomotor nerve
84
In the brain, which nuclei are involved in the light reflex
Pretectal nucleus - optic nerve synapses here | Edinger Westphal nucleus - passes signal to CN3
85
When the ciliary muscle is relaxed what happens
Used for far vision No parasympathetic input Suspensory ligaments tighten and lens flattens out
86
When the ciliary muscle is contracted what happens
Suspensory ligaments relax and the lens goes back to a spherical shape Allows near vision Uses parasympathetics
87
A rounded lens bends more light -true or false
TRUE
88
What is the accommodation reflex
Change in focus from far to near vision | To do this, the pupils constrict, there is bilateral convergence of eyes (cross eyed) and the lens relaxes
89
What are basal tears
The tears that clean, hydrate and nourish the cornea | Contain lysozyme - kills bacteria
90
What are reflex tears
Extra tears in response to mechanical or chemical stimulation Afferent limb is CN V1 from cornea/conjunctiva (sensory) Efferent limb is parasympathetic axons originating from CN VII (motor)
91
What are the functions of the eyelid
Protects the cornea | Spreads the tear film over the eye
92
Which muscle keeps the eye open unconsciously
Muller's muscle | collection of muscle fibres within levator palpibrae superiorus that has sympathetic innervation
93
Where is the mucous layer of the tear film produced
conjunctiva
94
What is the function of the mucous layer of the tear film
Keeps the other layers stuck to the eye
95
Where is the lipid layer of the tear film produced
By glands in the eyelids
96
What is the function of the lipid layer of the tear film
Stops the aqueous phase from evaporating too quickly
97
Where is the aqueous layer of the tear film produced
Lacrimal glands
98
Which part of the eye is responsible for refraction
Cornea
99
The shape of the cornea determines what
whether you need glasses or not
100
What is the function of the lens
Accommodation = changes shape to allow you to look near or far
101
The lens naturally sits in what shape
Sphere
102
What supports the lens of the eye
Zoonules (suspensory ligaments)
103
What is ametropia
When there is a refractive error present | Light is focused either in front or behind retina
104
What is anisometropia
When there is a significant difference in the refractive power of each eye Different prescription L and R
105
What is an astigmatism
This is when the eye has different refractive powers across it as the eye is more rugby ball shaped Treated with cylindrical lenses

Opthalmology (9 decks)

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