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BMB Test 3 > B7.040 Eye, Orbit, and Cranial Fossa > Flashcards

B7.040 Eye, Orbit, and Cranial Fossa Flashcards

1
Q

sclera

A

dense connective tissue continuous with dura mater of optic nerve and brain
white of eye

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2
Q

iris

A

pigmented diaphragm which surround the pupil

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3
Q

cornea

A

clear extension of the sclera which covers both the iris and pupil
provides 2/3 of focusing power of the eye

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4
Q

bulbar conjunctiva

A

thin, moist mucous membrane covering sclera

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5
Q

papebral conjunctiva

A

mucous membrane on inner surface of eyelids

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6
Q

lacrimal apparatus

A

lacrimal gland keeps mucous membranes of the eye moist
lacrimal caruncle in medial angle accumulates tears
superior lacrimal punctum is just lateral to the caruncle and is the beginning of the lacrimal canaliculus where tears are carried to the lacrimal sac
tears end up in nasolacrimal duct and drain into nasal cavity

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7
Q

pathway of tears

A 
lacrimal gland
caruncle
punctum
canaliculus
sac
nasolacrimal duct
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8
Q

why do you sniffle when you cry

A

tears usually dry up before entering the nasal cavity, but with excessive tears they do not and they cause sniffles

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9
Q

lacrimal gland

A

almond sized
in anterior/superior portion of orbit
produces 1 ml of tears each day
controlled by parasympathetic nerves from CN VII

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10
Q

eyelids

A

protect eye from drying and light

lined by thin skin on external surface and highly vascular palpebral conjunctiva on inner surface

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11
Q

tarsal plate

A

dense connective tissue plate that gives form to each eyelid

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12
Q

Meibomian glands

A

glands within the tarsal plates which secrete fatty lubricants which prevent the lids from sticking

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13
Q

orbital septum

A

normally keeps orbital fat within orbit

prevents herniation

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14
Q

what is a sty

A

acute purulent inflammation of the eyelid, generally caused by staph aureus

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15
Q

treatment of sty

A

resolves in days to weeks

warm washcloth helps melt lipids that cause blockage of sebaceous glands

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16
Q

internal sty

A

inflammation of a Meibomian gland just under conjunctival side of eyelid

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17
Q

external sty

A

arises from an eyelash follicle or lid-margin gland (sebaceous or apocrine)

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18
Q

chalazion

A

Meibomian gland lipogranuloma
lump on eyelid as a result of chronic blockage of a tarsal gland
same treatment as sty, may require lancing if warm compresses doesn’t work
usually not infected and not painful

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19
Q

conjunctivitis

A

can be called pinkeye

commonly caused by allergic reaction (non infectious) or infections which are usually viral, but sometimes bacterial

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20
Q

allergic conjunctivitis

A

typically itchy

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21
Q

viral conjunctivitis

A

associated with a cold

watery discharge, variable itch

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22
Q

bacterial conjunctivitis

A

marked grittiness/irritation and a stringy, opaque, grey or yellowing mucopurulent discharge that may cause the lids to stick together

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23
Q

conjunctivitis prophylaxis

A

newborns delivered vaginally get antibacterial agents to protect against venereal diseases

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24
Q

2 muscles which raise the upper eyelid

A 
levator palpebrae superioris
superior tarsal (Muller)
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25
levator palpebrae superioris
skeletal muscle under voluntary control innervated by CN III | main elevator
26
superior tarsal
smooth muscle innervated by sympathetic fibers | if innervation is lost, can cause 2 mm droop (ptosis)
27
horner's
1. ptosis (loss of superior tarsal innervation) 2. miosis (loss of dilator muscle in pupil) 3. anhidrosis (loss of sym input to sweat gland)
28
muscle that closes the eyelid
orbicularis oculi | innervated by CN VII
29
what is an orbital blow out fracture
breakage of maxillary bone (inferior wall of orbit) with subsequent protrusion of orbital contents into maxillary sinus
30
clinical features of orbital blow out
inability to look up due to trapping of inferior rectus in the maxillary bone fracture lowered globe level cause by prolapse of soft tissue
31
superior orbital fissure
located at apex of orbit between lesser and greater wings of sphenoid bone transmits CN III, CN IV, ophthalmic CN V1, CN VI, and superior ophthalmic vein into orbit
32
optic canal
transmits optic CN II and ophthalmic artery
33
rectus muscles
move orbit and pull eye deeper into socket
34
oblique muscles
cause torsion of the orbit and protrusion of the eye forward within the orbit
35
graves disease eye findings
hyperthyroidism eyes protrude slightly (proptosis) exophthalmos - may be due to increased size of EOMs and edema within the orbit due to autoimmune reaction to thyrotropin (TSH) receptor antigen which is expressed in retroorbital tissues
36
annual ring of Zinn
common tendinous ring which surrounds the optic canal and superior orbital fissure 4 rectus muscles arise from here
37
origin of superior oblique
runs through a pulley, the trochlea, which is attached to the superior/medial margin of the frontal bone
38
origin of inferior oblique
arises from the maxillary bone margin just lateral to the nasolacrimal duct
39
insertion of superior oblique
sclera of eye in the superior, posterior, and lateral portion
40
insertion of inferior oblique
sclera of the eye in the inferior surface in the posterior, lateral quadrant
41
strabismus
pathological misalignment of the visual axes that cause a loss of depth perception and binocular vision
42
incidence of strabismus
``` 2-3% of general population 3 mil in US annually more prevalent in Caucasian females multifactorial inheritance onset before age of 5 ```
43
cause of strabismus
variation in the insertions of EOMs into orbit
44
esotropia
one or both eyes turn inward | "cross eyed"
45
exotropia
one eye deviates outward | less common
46
eye adductors
MR SR IR
47
eye abductors
IO SO LR
48
eye elevators
IO | SR
49
eye depressors
SO | IR
50
medial rotators (intorsion)
SR | SO
51
lateral rotators (extorsion)
IR | IO
52
H test important
when lateral: SR and IR do vertical movements | when medial: IO and SO do vertical movements
53
oculomotor nerve lesion
1. lateral strabismus (down and out due to unopposed LR and SO) 2. ptosis (paralysis of levator palpebrae) 3. dilation of pupil 4. loss of lens accommodation
54
causes of sudden CN III palsy
aneurysm within posterior communicating cavernous sinus thrombosis subarachnoid hemorrhage
55
contraction of SO muscle
eye rotates outward, downward, and with intorsion
56
lesion of CN IV
patient tilts head toward unaffected side bc side with lesion is extorted
57
CN VI palsy
weakness or paralysis of LR eye on affected side rotates inward, medially due to unopposed MR action causes diplopia
58
cause of CN VI palsy
conditions which increase ICP stretch the abducens nerve as brainstem is pushed into foramen magnum most common CN palsy, found in diabetics
59
anterior chamber
anterior to iris and pupil filled with aqueous humor drains in canal of Schlemm at junction of the iris which the cornea and sclera (anterior chamber angle) into the venous blood
60
posterior chamber
posterior to iris and pupil, but in front of lens and ciliary process contains ciliary body which produces aqueous humor which flows out of pupil into anterior chamber
61
glaucoma
excessive pressure within the eye | second leading cause of blindness in the world (leading in AAs)
62
closed angle glaucoma
10% | blockage of fluid drainage at the canal of schlemm
63
glaucoma exam
blowing a jet of air into the cornea and measuring the deformity
64
open angle glaucoma
90% | overproduction of aqueous humor
65
muscles in the iris
1. radial, dilator muscle | 2. circular, sphincter muscle
66
pupil dilator muscle
myoepithelial cells innervated by ganglionic sympathetics from superior cervical ganglia a1 receptors respond to NE
67
cocaine
inhibits reuptake of NE, dilating eye
68
pupil sphincter muscle
smooth muscle innervated by postganglionic parasympathetic fibers from ciliary ganglia via short ciliary nerves muscarinic ACh receptors
69
anticholinergics
atropine and tropicamide | cause pupil dilation as dilator muscle is unopposed
70
accommodation
lens changes shape to focus on near objects
71
distance vision
ciliary muscle is relaxes, ligaments pull on and flatten the lens
72
near vision
ciliary muscle contracts, releases tension on the ligaments and the lens becomes more rounded
73
presbyopia
lens elasticity lost with age common many older individuals have difficult reading without the aid of reading glasses (far sighted) lens does not round up as much as it used to
74
cataract
clouding of the lens common (half of people in US have them by 80) develop slowly and can affect one or both eyes, typically in those over 50
75
risk factors for cataracts
diabetes, smoking, prolonged sun exposure, alcohol, genetics
76
exposure of central vein and artery to CSF pressure
course inside the optic nerve | CSF pressure is transmitted into the orbit
77
papilledema
excessive CSF pressure as determined via exam of fundus | causes optic disc to swell and blood, especially venous blood to pool in the veins on the surface of the retina
78
fundus during hypertension
arteries become swollen and tend to restrict venous return | venous nicking
79
cavernous sinuses
dural sinuses 2 cm long and 1 cm wide located on each side of the sella turcica and body of sphenoid bone connected by intercavernous sinuses and receive blood from superior and inferior ophthalmic veins, superficial middle cerebral, and sphenoparietal sinus rained by superior and inferior petrosal sinuses
80
carotid-cavernous sinus fistula
rare if an aneurysm in the internal carotid artery ruptures into the cavernous sinus, then the affected eye/orbit may fill with blood and pulsate blood suddenly appears in sclera and orbital tissue as superior and inferior ophthalmic veins become pressurized close to arterial pressures
81
AVMs
arterial venous malformations cerebral arteries and veins form abnormal tangles or webs can be clinically silent or bleed and cause infarction in nearby parts of the brain
82
symptoms of carotid-cavernous sinus fistula
``` pulsating exophthalmos (forward protrusion of the eye) extraocular palsies (CN III, IV, and VI run through cavernous sinus) ```
83
treatment of carotid-cavernous sinus fistula
insertion of a balloon or coil into shunt via a catheter or surgery
84
corneal reflex
mediated by sensory fibers of CN V1 and motor fibers of CN VII bilateral blink response when edge of cornea is touched
85
example of cause of dysfunction of corneal reflex
VIII tumors (acoustic neuromas) can compress CN VII in acoustic meatus
86
contents of anterior cranial fossa
frontal lobes of the cerebral hemispheres orbital plates of frontal bones crista galli and cribriform plate of the ethmoid bone; the falx cerebri sphenoid ridge clinoid processes
87
falx cerebri
attaches to frontal crest and crista galli
88
sphenoid ridge
formed by lesser wing of the sphenoid
89
clinoid processes
site of attachment for tentorium cerebelli
90
contents of middle cranial fossa
``` temporal lobes dorsum sellae posterior clinoid processes petrous squamous ```
91
dorsum sellae
behind sella turcica of sphenoid bone
92
posterior clinoid processes
of sphenoid bone
93
petrous
portion of temporal bones
94
squamous
portion of temporal bones
95
posterior cranial fossa
occipital lobes lying on tentorium cerebelli, cerebellum, pons, and medulla occipital bone tentorium cerebelli

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