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Opthamology > Anatomy > Flashcards

Flashcards in Anatomy Deck (115)
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1
Q

What makes up the roof border of the orbit

A

The frontal plate of the frontal bone and the lesser wing of the sphenoid

2
Q

Role of the roof border

A

separates the orbit from the anterior cranial fossa

3
Q

What makes up the lateral border of the orbit

A

The zygomatic bone and the greater wing of the sphenoid

4
Q

role of the lateral border of the orbit

A

separates the temporal fossa from the orbit

5
Q

What makes up the floor of the orbit

A

maxillary bone and the zygoma

6
Q

role of the roof of the orbit

A

separates the orbit from the maxillary air sinuses

7
Q

role of the medial border of the orbit

A

separates the orbit from the ethmoidal air sinuses

8
Q

what makes up the medial border of the orbit

A

the maxilla, the orbit plate of the ethmoid, the body of the sphenoid and the lacrimal bone

9
Q

what is the apex of the orbit and what does it contain

A

the orbit canal and it contains the optic nerve and ophthalmic artery

10
Q

orbital blow out #

A

medial and inferior walls are thin so a direct blow may cause a #

11
Q

risks of a medial orbit wall #

A

ethmoidal and sphenoidal sinuses may be involved

12
Q

risks of a inferior wall #

A

the maxillary air sinuses may be involved and the infraorbital nerve which can cause altered sensation of cheek. May also have diplopia.

13
Q

What does an eye lowered to the inferior orbital floor and diplopia suggest?

A

zygoma # which has rotated medially

- remember the suspensory ligaments are attached laterally to the zygoma

14
Q

The layers of the eyelid from superficial to deep

A
skin and superficial fascia
orbicularis occuli 
tarsal plates
levator apparatus
conjunctiva
15
Q

Parts of the orbicularis occuli muscle

A

orbital part and the palpebral part

16
Q

innervation of the orbicularis occuli

A

facial nerve CNVII

17
Q

role of the orbicularis occuli muscle?

A

orbital part - tightly close the eye

palpebral part- gently close eyelid

18
Q

What is the orbital septum and where is it found?

A

sheet of fascia between the orbicularis occuli and the tarsal plates that helps prevent the spread of infection from superficial to deep

19
Q

What are tarsal plates?

A

2 plates deep to the palpebral region of the orbicularis muscle. 2 plates: superior tarus (upper eyelid) and the inferior tarus (lower eyelid)

20
Q

role of the tarsal plates

A

contain tarsal glands(Meibomian gland) that secrete an oily substance to keep the eyes moist and prevent them sticking when eyes are closed
also give structure

21
Q

what is the levator apparatus

A

2 muscles that act to open the eyelid: levator palpebrae superialis (LPS)and the superior tarsal muscles
only present in the upper eyelid

22
Q

role of the LPS and innervation

A

opens the eyelid and is innervated by the oculomotor nerve CNIII

23
Q

Location of the superior tarsal muscle, innervation and role

A

Underneath the LPS
assists the LPS in opening the eye
sympathetically innervated

24
Q

what is conjunctiva

A

thin mucous membrane folded onto the sclera

25
Q

What is the pupil?

A

gap in the iris which allows light to be passed through before being focused on the retina

26
Q

What is the limbus?

A

where the cornea and sclera meet- the corneascleral junction

27
Q

what secretes lacrimal fluid and where is it secreted?

A

lacrimal gland

secretes fluid onto the conjunctiva and cornea of the eye

28
Q

where is the lacrimal gland located?

A

anterior in the superiolateral aspect of the orbit in the lacrimal fossa (depression in the frontal bone)

29
Q

what innervates the lacrimal gland

A

parasympathetic CNVII

30
Q

direction of travel of lacrimal fluid

A

fluid is produced in the lacrimal gland and is washed over into the medial angle of the eye where in travels through the lacrimal punctuae into the canaliculi into the lacrimal sac then into the nasolacrimal duct where it eventually meets the inferior meatus.

31
Q

location of the nasolacrimal duct

A

in a groove formed by the lacrimal and maxilla

32
Q

How many layers of the eye are there? What are there names?

A

3:
fibrous (outer)
Uvea (middle)
Retina (inner)

33
Q

What is contained in the fibrous layer and what is their role?

A

Sclera and cornea

sclera: muscle attachment
cornea: major refractive power

34
Q

What is in the uvea (and their function) and what is characteristic about the uvea?

A

VVVV vascular
Iris: controls pupil diameter and consequently how much light in
choroid: gas and nutrient exchange
ciliary body: contains ciliary muscles for accommodation and secretes aquaeous humour

35
Q

What is included in the retina and what is the function

A

fovea
Optic disc: where the optic nerve enters
macula

36
Q

What is the difference between the anterior segment and posterior segment?

A

Anterior segment is infront of the lens, the posterior segment is behind the lend

37
Q

What is the posterior segment filled with

A

virteous humour

38
Q

how is the anterior segment divided and what is it filled with?

A

Anterior chamber: between iris and cornea
Posterior chamber: iris and suspensory ligaments
both filled with aqueous humour

39
Q

Differences in production between aquaeous humour and virteous humour?

A

Aquaeous is continuously produced whereas virteous is not

40
Q

Circulation of aquaeous humour

A

Secreted by ciliary body into the posterior chamber and nourishes the lens.
it then travels through the pupil into the anterior chamber and nourishes the cornea and is then reabsorbed at the canal of schelmn @ iridocorneal angle.

41
Q

blood supply to the eye and main branches

A

ophthalmic artery (branch of int carotid)
2 main branches:
central artery of the retina (end)
Ciliary arteries

42
Q

why is the central artery of the retina so important?

A

its an end artery so occlusion leads to blindness vvv quickly

43
Q

venous supply to orbit

A

superior and inferior ophthalmic veins
the inferior mainly drains into superior vein and they both then drain into the cavernous sinus
the facial vein also does a tiny amount

44
Q

what is the danger triangle

A

between eyes over nose and down to upper lip… abscess here would be drained back into the cavernous sinus and couls cause a cavernous sinus thrombosis which is life threatening

45
Q

What is the optic disc and where is it located?

A

located medially on the posterior wall of the retina. it is where the optic nerve CNII leaves the eyeball and where arteries/ veins enter/leave. (no photoreceptors)

46
Q

Where is your blind spot?

A

optic disc

47
Q

Where is the macula and what is the function?

A

Just lateral to the optic disc and has the greatest density of cone cells so v important for light vision.

48
Q

Where is the fovea and what is its function?

A

just lateral to the optic disc in the centre of the macula. it is must important for vision acuity (sharp images not blurred)

49
Q

How many extraocular muscles are there and what are they called?

A
7
superior rectus 
inferior rectus
medial rectus
lateral rectus 
superior oblique 
inferior oblique 
1 levator palpebrae superioris
50
Q

Attachments of extraocular muscles

A

all originate from the common tendinous ring and attach onto the sclera

51
Q

what is the somatic motor innervation of the extraocular muscles

A

LR6
SO4
AO3

52
Q

Innervation and clinical test of lateral rectus

A

abduction into the same plane and the sup and inf rectus

CNVI

53
Q

Innervation and clinical test of superior rectus

A

Elevates eye when it is abducted

CNIII

54
Q

innervation and function of inferior rectus

A

CNIII

when the eye is abducted it depresses the eye

55
Q

innervation and clinical test of medial rectus

A

innervated by CNIII

adducts the eye

56
Q

innervation and clinical test of inferior oblique

A

elevates the eye when it is adducted

CNIII

57
Q

innervation and clinical test of superior oblique

A

depresses the eye when it is adducted

CNIV

58
Q

muscles involved in pure elevation

A

inferior oblique and superior rectus

59
Q

muscles involved in pure depression

A

inferior rectus and superior oblique

60
Q

What is the sensory innervation of the face and the divisions

A
Trigeminal nerve CNV
it has 3 divisions: 
CNV1: opthalmic
CNV2: maxillary 
CNV3: Mandibular
61
Q

What is the name of nerve V1 and what it innervates

A

Opthalmic:

  • upper eyelid
  • cornea
  • conjunctiva
  • skin down centre of nose
62
Q

Name of nerve V2 and what it innervates

A

Maxillary:

  • side of nose
  • lower eyelid
  • skin of lower lip
  • maxilla
63
Q

Name of nerve V3 and what it innervates

A

Mandible:
- bottom lip
skin over mandible and temporomandibular joint

64
Q

What innervates the temporomandibular joint

A

Supplied by spinal nerves C2 and C3

65
Q

Explain the corneal Reflex:

A

Sensory/Afferent:
AP conducted from cornea via CNV1 to terminal ganglion then along CNV to pons
There is a CNS connection between CNV and CNVII
Motor/Efferent:
AP conducted along CNVII to the palpebral part of the occularis occuli to cause blinking

66
Q

where do sympathetic axons exit the spinal cord

A

T1-L2 spinal nerves

67
Q

How is sympathetic outflow describes

A

Thoracolumbar

68
Q

What are splanchnic nerves

A

supply blood vessels and visceral organs (symp axons)

69
Q

How do sympathetic axons from the spinal cord reach the orbit

A

pre synaptic sympathetic axons leave the spinal cord at T1 spinal nerve and ascend upwards with the sympathetic trunk and synapse in the superior cervical sympathetic ganglion.

post synaptic sympathetic axons enter the internal and external carotid nerves and pass onto the surface of internal and external carotid arteries. they are carried to the organs of head and neck on the surface of the branches of the internal and external carotid arteries. the ophthalmic artery carries sympathetic axons in the orbit.

70
Q

What artery carries sympathetic axons to the orbit

A

ophthalmic artery

71
Q

What cranial nerves are parasympathetic

A

X, IX, VII, III

72
Q

how is the parasympathetic supply described

A

Craniosacral

73
Q

Where does CN III synapse

A

ciliary ganglion

74
Q

where does CN VII synapse

A

synapses in pteygopalatine ganglion and the post synaptic fibres travel to the lacrimal gland

75
Q

where does the parasympathetic sacral spinal nerves innervate

A

hindgut
pelvis
peroneoum

76
Q

What is the name of CN III

A

Oculomotor

77
Q

Is CN III motor or sensory?

A

Motor

78
Q

Is CN III sympathetic or parasympathetic?

A

Parasympathetic

79
Q

Route of CN III

A

passes through the cavernous sinus, exits via superior orbital fissue and enters orbit

80
Q

Where does the oculomotor supply somatic motor supply to?

A
SR
IR
MR
IO
LPS
81
Q

Where does CN III synapse and what occurs after synapse?

A

Synapses at ciliary ganglion
gives off 2 division superior and inferior
superior innervates: SR, LPS
inferior innervates: IR, IO, MR and ciliary ganglion

82
Q

What does the autonomic (sympathetic) axons in the ciliary nerve control

A

Diametre of iris
refractive shape of lens
(sympathetic innervates the sphincter papillae muscles)

83
Q

Difference in short and long ciliary nerves

A

long: sympathetic and somatic sensory
short: sympathetic and parasympathetic

84
Q

what are the autonomic reflexes of the eye

A
wide eye opening
pupillary dilation/constriction
accommodative reflex
lacrimation production 
vestibulooccular reflex
occulocardiac reflex
85
Q

What the sympathetic reflexes in the eye

A

OPens eye wider
get more light into eyes
focus on far objects
emotional lacrimation

86
Q

what reflexes are the parasympathetic reflexes in the eye

A
Get less light into eye
focus on near objects
reflex lacrimation (foreign body)
87
Q

What muscle is responsible for the opening eyes wider response

A

LPS

88
Q

What muscle does the LPS contain and what is the innervation

A

Smooth and skeletal muscle
the skeletal muscle is innervated by the oculomotor nerve
the smooth muscle is sympathetically innervated to allow allow fight or flight

89
Q

how do the sympathetic fibres reach the LPS muscle

A

leave the spinal cord and travel to the superior cervical sympathetic ganglion then axons travel via the internal carotid artery via a plexus then the artery divides and the axons are carried on the ophthalmic artery

90
Q

What nervous system causes pupillary dilation and in what scenario does it happen

A

SYMPATHETICS

in dim light, flight or fight or if PT is sick

91
Q

what is a mydriatic pupil and what causes it

A

Non physiologically enlarged pupil

mydriatic drug

92
Q

what fibres causes pupil dilation and how

A

dilator pupillae fibres (originate around the external circumference of the iris and insert around the internal circumference of iris)
supplied by the symp nervous system- contraction of the pupillae causes pupil dilation

93
Q

What nervous system causes pupil constriction and in what scenario does it happen?

A

Parasympathetic

occurs in bright light and rest and digest

94
Q

what is a miotic pupil and what is it a component off

A

non-physiologically enlarged pupil

component of horners syndrome

95
Q

What can a fixed dilated or fixed pin point pupil suggest

A

fixed dilated: CN III pathology

fixed pin point: opiates

96
Q

what muscles cause pupil constriction

A

sphincter pupillae fibres encircle the pupil and there contraction causes constriction

97
Q

what is the pupillary light reflex and the mechanism

A

when a light is shone in one eye it causes bilateral constriction
Sensory: signal sent by the optic nerve (CN II: IPSILATEAL)
CNS connections occur in midbrain
Motor: signal is bilateral along CNIII (oculomotor)

98
Q

what is the direct light reflex

A

constriction in the eye stimulated with light

99
Q

what is the consensual light reflex

A

constriction in the non stimulated eye

100
Q

what is the 4 neurone chain of the pupillary light reflex

A

1) retinal ganglion cells send an AP via the ipsilateral optic nerve which crosses at the optic chiasm and synapses in the pretectal nucleus
2) located in midbrain and connects the pretectal nucleus to the next synapse the Edinger Westphal nucleus (bilateral )
3) pass from the EW nucles to the CNIII then to its inferior division to synapse in the ciliary ganglion
4) course in the short ciliary nerves to the sphincter papillae muscles

101
Q

what is the refractive power of the lens vs the cornea?

A

cornea: 2/3 of refractive power
lens: 1/3 of refractive power

102
Q

what connects the lens and ciliary body

A

suspensory ligament of lens

103
Q

what controls the shape of the lens

A

parasympathetic

104
Q

describes what happens in relaxation of the ciliary muscles

A

relaxation of the ciliary muscles puts tension on the suspensory ligaments causing the lens to flatten out
happens in long vision
happens when the parasympathetic supply is switched off

105
Q

describe what happens in contraction of ciliary muscles

A

contraction of the ciliary muscles causes the suspensory ligament to relax and the lens to become spherical
occurs in short vision
happens under parasympathetic stimulation

106
Q

what shape of lens has a greater refractive e power

A

spherical has a greater refractive power than flat

107
Q

what is the natural position of your lens

A

spherical

108
Q

why do people need reading glasses as they get older

A

lens becomes less flexible and more fibrous so cannot spring into sphere as easily

109
Q

what is the accommodative light reflex and why is it needed

A

changing focus distance
if looking at something in the distance the cornea does enough light bending to focus an image on the retina whereas close up the cornea is not enough to bend an image and the lens in needed

110
Q

how do you clinically asses the accommodative reflex

A

ask the patient to look at something in the distance and then to quickly look at something very close in the midline

111
Q

what 3 components are assessed in the accommodative reflex:

A

1) bilateral pupillary constriction
2) bilateral convergence
3) bilateral relaxation of lens

112
Q

what are the 3 types of lacrimation

A

1) basal
2) reflex
3) emotional

113
Q

what are basal tears

A

constant tears that clean and nourish cornea. also contain lysosome the enzyme that degrades bacterial cell walls.

114
Q

what are reflex tears

A

tears in response to mechanical or chemical stimulation. afferent in CN V1 and efferent is CN VII (autonomic parasympathetic)

115
Q

what is horners syndrome and what are the symptoms

A

horners is impaired sympathetic innervation to the head and neck
symptoms are ipsilateral: miosis, ptosis, reduced sweating and inc warmth and redness