Ocular Anatomy (with some accidental Disease mixed in) Flashcards
1
Q
What is sclerotic scatter used to look for?
A
Corneal edema
2
Q
What is the illumination angle for sclerotic scatter?
A
60 degrees
3
Q
What is an optic section used for?
A
Depth assessments - angle, corneal lesions
4
Q
About how wide should an optic section be?
A
0.5mm
5
Q
What is specular reflection used for?
A
Evaluate corneal endothelium and anterior/posterior lens surfaces
6
Q
What is indirect illumination used to view?
A
Non-opaque corneal lesions
7
Q
When a cobalt filter is used without fluorescein, what is highlighted, and in what color, that is commonly found in keratoconus?
A
Fleischer rings - corneal iron rings
Appear black
8
Q
What may happen to IOP in cases of severe chemical burns?
A
Increase
9
Q
Why are alkali burns worse than acid burns?
A
They raise tissue pH, breaking down fatty acids, allowing for faster penetration
10
Q
Which are more common, alkali burns or acid burns?
A
Alkali - 2x as common
11
Q
What is the most common cause of alkali burns?
A
Calcium hydroxide
12
Q
In which type of chemical burn is limbal blanching more common?
A
Alkali
13
Q
What are the common symptoms of a corneal abrasion?
A
Pain FBS Photophobia Tearing Blurred vision Mild AC reaction Miotic pupil
14
Q
A corneal abrasion typically stains with fluorescein, but doesn’t have what?
A
SEIs
15
Q
What should always be done before removing a corneal foreign body?
A
Check VA
16
Q
What is hyphema?
A
Blood in the AC
17
Q
What systemic diseases may cause hyphema?
A
Sickle-cell retinopathy
Clotting disease
(others)
18
Q
What typically causes hyphema?
A
Trauma to the iris and/or ciliary body
19
Q
What should NOT be performed on a patient with hyphema?
A
Gonio
Scleral depression - they can cause re-bleeds
20
Q
How long after an injury that causes hyphema can gonio be performed?
A
About 1 month
21
Q
What are some additional signs associated with hyphema?
A
Iris sphincter tear Iridodialysis Cataract (traumatic) Vossius ring on anterior lens capsule Commotio retinae Angle recession
22
Q
Why might there be a significant IOP increase in a patient with hyphema?
A
Blood cells block the TM, blocking outflow
23
Q
What should you ask about if a patient presents with an idiopathic hyphema?
A
Use of blood thinners
24
Q
What tests might you order if a patient presents with idiopathic hyphema?
A
CBC
Prothrombin time/partial thromboplastin time
Sickle cell screen
25
Which ethnicities have a higher prevalence of sickle cell?
African American
| Mediterranean
26
Which type of intraocular foreign might cause significant inflammation?
Iron
Steel
Copper
Vegetable matter
27
What bone breaks in an orbital blow out fracture?
Maxillary bone
28
A patient presents with a blow out fracture and complains of loss of sensation of the cheek. What is the probable cause?
Damage to the infraorbital nerve
29
What is commotio retinae of the macula termed?
Berlin's edema
30
What is iridodialysis?
Disinssertion of the iris root from the ciliary body
31
If a patient has an iridodialysis, what should they be monitored for?
Angle recession glaucoma
32
What is Purtscher's retinopathy commonly associated with?
Chest compressing trauma
33
What characterizes Purtscher's retinopathy?
Diffuse retinal hemorrhages
Exudates
Cotton wool spots
34
Acute pancreatitis may also cause this type of retinopathy that is commonly associated with chest-compressing trauma.
What is: Purtscher's retinopathy
35
What does choroidal rupture usually appear as?
Single or multiple areas of subretinal hemorrhage, usually within the temporal posterior pole, with crescent shaped tears concentric to the optic nerve head
36
Choroidal rupture occurs in 5-10% of what?
Blunt trauma
37
What is the name for the most superficial portion of the orbicularis oculi?
Muscle of Riolan
38
What is the function of the Muscle of Riolan?
Keeps lid margin apposed to the globe during eye movement
39
Do the meibomian glands arise anterior or posterior to the Muscle of Riolan (gray line)?
Posterior
40
Which is the thinnest of the corneal layers?
Endothelium
41
What are the layers of the cornea from anterior to posterior?
```
Epithelium
Bowmans
Stroma
Descemet's
Endothelium
```
42
Which layer of the cornea thickens with age?
Descemet's membrane
43
What vascular system nourishes the lens during fetal development?
Cloquet's canal (hyaloid vascular system)
44
What is a remnant of Cloquet's canal left on the posterior lens called?
Mittendorf dot
45
What is a Bermeister Papilla?
Remnant of cloquet's canal left on the optic disc
46
What 3 cell types are found within the foveola?
PRs (cones)
Glial cells
Muller cells
47
What 5 retinal layers are found within the foveola?
```
RPE
PRs
ELM
ONL
Henle's fiber layer
ILM
```
48
What is the size of the fovea?
1.5mm or 1500 micrometers or 1 DD
49
What are the approximate thickness of the cornea?
Cornea - 550 microns
50
What is the thickness of the thinnest part of the choroid, and where is it located?
Ora serrata
| .1mm
51
What is the thickness of the thickest part of the choroid, and where is it located?
Posterior pole
| .2mm
52
How thick is the thickest part of the sclera, and where is it located?
1.0mm
| Near the ONH
53
Where is the thinnest part of the sclera, and what does it measure?
Insertions of the rectus muscles
| .3mm
54
How thick, and where is the thickest part of the retina?
Papillomacular bundle
| .23mm
55
How thick, and where is the thinnest part of the retina?
.1mm
| Foveola
56
What are the 2 functions of the ciliary body?
Accommodation
| Aqueous humor formation
57
What 2 cranial nerves transmit parasympathetic innervation to ocular structures?
CN 3
| CN 7
58
Where do the parasympathetics begin for CN 3?
Edinger Westphal Nucleus
59
What structures and receptors are innervated by the parasympathetics from CN 3?
Ciliary body - M2 and M3 receptors
| Sphincter muscle - M3 receptors
60
From where does the Edinger Westphal nucleus arise?
Midbrain
61
Where do the parasympathetics begin for CN 7?
Lacrimal nucleus
62
From where does the lacrimal nucleus arise?
Pons
63
What structures and receptors are innervated by the parasympathetics from CN 7?
Lacrimal gland - M2, M3 receptors
64
What is the course of the parasympathetics that arise from CN 3?
Edinger Westphal nucleus
Ciliary ganglion
Innervates ciliary body and sphincter muscle
65
What is the course of the parasympathetics that arise from CN 7?
Lacrimal nucleus
Sphenopalatine ganglion
Innervates lacrimal gland
66
Parasympathetics to the eye innervate what 3 structures?
```
Lacrimal gland (CN 7)
Ciliary muscle (CN 3)
Sphincter muscle (CN 3)
```
67
What 3 structures make up the uvea?
Iris
Ciliary body
Choroid
68
What is required for the formation of a CNVM?
A break in Bruch's membrane
69
What are 4 conditions that can cause a break in Bruch's membrane?
Exudative ARMD
Lacquer cracks
Angioid streaks
Histoplasmosis
70
What are the 2 xanthophyll pigments found in the macula?
Lutein
| Zeaxanthin
71
What is the relationship of lutein and zeaxanthin to ARMD risk?
The act as antioxidants, and so protect against ARMD
72
How many layers of ganglion cells are contained in the macula?
2 or more layers of ganglion cells
73
What are the 2 types of sinuses within the cranium?
Air - ex. paranasal
| Blood - ex. cavernous
74
What would be the expected facial finding in a patient with a lesion of the superior division of CN III?
Ptosis
75
What condition results from a lesion at the location of the ciliary ganglion?
Adie's tonic pupil - the ciliary ganglion carries parasympathetics from CN 3 to the ciliary body and sphincter muscle
76
What are the findings of Adie's tonic pupil?
Unilateral dilated pupil
77
Which nervous system is affected in Adie's tonic pupil?
Parasympathetic - sympathetic takes over and dilates the pupil
78
What drug is used for diagnosis of Adie's tonic pupil?
Pilocarpine 0.125%
79
Patient's with Adie's tonic pupil will have a delayed what?
Light response
| Near response
80
Why do patient's with Adie's tonic pupil have a delayed light and near response?
There is a lesion of the ciliary ganglion, which is responsible for both the light and near response
81
Which cranial nerve is used for shoulder shrugging/head turning?
XI - accessory
82
The optic nerve gives off fibers to what 3 structures?
LGN
Pretectal nucleus
Superior colliculus
83
Where do preganglionic parasympathetic fibers that course to the pupil originate?
Edinger Westphal nucleus
84
Where do postganglionic parasympathetic fibers that course to the pupil originate?
Ciliary ganglion
85
What bones make up the medial wall of the orbit?
Sphenoid (body)
Maxilla
Ethmoid
Lacrimal
86
What bone makes up the majority of the floor of the orbit?
Maxillary bone
87
What degree of abduction makes the inferior rectus the primary depressor?
23 degrees
88
Which muscle cause intorsion, abduction, and depression?
Superior oblique
89
When are the oblique muscles responsible for elevation and depression?
When the eye is adducted 51-55 degrees
90
If a patient is instructed to look straight up, which muscles are performing this action?
Superior rectus
| Inferior oblique
91
Where does the inferior oblique muscle start its course?
Maxillary bone
92
Which 2 bones make up the lateral wall of the orbit?
Zygomatic bone
Greater wing of sphenoid
(Lateral wall = Great-Z)
93
The bulbar conj and ciliary body both receive part of their blood supply from which vessels?
Anterior ciliary artery
94
What comprises the major arterial circle of the iris?
Long posterior ciliary arteries
| Anterior ciliary arteries
95
Where is the major arterial circle of the iris located?
In the ciliary body
96
Why does a uveitis patient have inflammation of the ciliary body and circumlimbal injection?
Because they are both supplied by the anterior ciliary arteries
97
Lateral conj lymphatics drain into what?
Preauricular lymph nodes
98
Medial lymphatics drain into what?
Submandibular lymph nodes
99
Which glands lubricate the eyelashes?
Glands of Zeis
100
What is a second major function of the glands of Zeis?
Assist the glands of Moll and meibomian glands to produce the lipid layer of the tear film
101
Which layer of the tear film is secreted by blinking?
Lipid layer
102
What produces the lipid layer of the tear film?
Goblet cells
103
A deficiency in what will cause decreased production from goblet cells, causing evaporative dry eye?
Vitamin A
104
Which layer of the eyelid contains goblet cells?
Palpebral conjunctiva
105
What pupil abnormality would be most prevalent in the light?
Adie's tonic pupil - (acute, dilated pupil)
106
Which pupil abnormality is most prevalent in the dark?
Horner's
107
Sympathetic innervation to the dilator follows the course of which sensory nerve?
Nasociliary nerve
108
Sympathetics on the nasociliary nerve have what two options?
Go to pupil dilator
| Go to Muller's muscle
109
What nervous fibers does a pancoast tumor upset?
Sympathetic fibers
110
What are the symptoms of a pancoast tumor?
```
Miosis
Ptosis
Reverse ptosis
Anhydrosis
Dilation lag
(Much like Horner's)
```
111
Does a Pancoast tumor affect pre or post ganglionic sympathetic fibers?
Preganglionic - synapse in the superior cervical ganglion
112
Why does Bell's cause ipsilateral paralysis?
It is damage to a lower motor neuron, so it stays ipsilateral
113
What is the main ocular concern with Bell's palsy?
Exposure keratopathy
114
Bell's palsy is an idiopathic palsy of what nerve?
CN 7
115
What is the main ocular function of CN 7?
Close the eye
116
A patient with a pupil involved CN 3 palsy should be suspected of an aneurysm at the junction of what 2 arteries?
Posterior communicating artery
| Internal carotid
117
A pupil sparing CN 3 palsy typically occurs from what 2 systemic diseases?
HTN
| DM
118
A lesion of the facial nerve would elicit what symptoms?
Loss of anterior 2/3 taste
Loss of facial expression
Loss of lacrimation
Loss of sound dampening
119
Which cranial nerve is most likely affected in a patient with papilledema?
CN VI - due to the intracranial course ( and no protection by the cavernous sinus, like the other nerves) a rise in pressure will most affect this nerve
120
What nerve innervates the lateral conj and lateral portion of the upper eyelid?
Lacrimal nerve (of V1)
121
What nerve innervates the lateral part of the lower eyelid?
Zygomatic nerve (of V2)
122
A palsy of which muscle will cause a patient to tilt their head to to opposite side of the palsy?
CN 4 - the entire nerve decussates, and the head tilts toward the side of the nuclear lesion, but away from the palsy
123
Which extra ocular muscle has a different anatomical and physiological origin?
Superior Oblique
124
What is the anatomical origin of the superior oblique?
Lesser wing of the sphenoid, and common tendinous ring (annulus of Zinn)
125
What is the physiological origin of the superior oblique?
Trochlea
126
Inability for a patient to look up during abduction is most likely a result of a lesion of what nucleus?
Contralateral superior rectus
| -SR fibers decussate
127
Which lens fibers are the most immature?
Lens cortex
128
Which region of the lens continues to grow throughout life?
Cortex
129
What are the vitreo-retinal attachments from strongest to weakest?
```
Ora serrata
Posterior lens
Optic nerve
Macula
Retinal vessels
```
130
The posterior pigmented iris epithelium is continuous with what?
Nonpigmented ciliary body epithelium and neural retina
131
How does accommodation influence IOP?
Ciliary muscle contracts, pulling on the scleral spur, which is attached to the TM, pulling it open and opening the pores, increasing outflow
132
Where do the lens zonules begin?
Pars plana of the ciliary body
133
What part of the ciliary body secretes aqueous?
Pars plicata
134
What is another name for the pars plicata?
Corona cilaris
135
What percent of the eye does the vitreous comprise?
80%
136
The pupillary ruff is formed by what layer of the iris?
Posterior pigmented epithelium
137
Which layer of the iris is the primary contributor to iris color?
Anterior border layer
138
Which iris layer is a minor contributor to iris color?
Iris stroma
139
Which veins drain Schlemm's Canal?
External collector channels
Deep scleral venous plexus
Intrascleral veins
Episcleral veins
140
Where do corneal stem cells originate?
At the Pallisades of Vogt (limbus)
141
Which corneal epithelia cells are the only type that undergo mitosis?
Basal cells
142
Corneal limbal stem cells become what type of cell?
Basal cells
143
When a corneal basal cells undergoes mitosis, what does it produce?
Wing cells
144
What is the approximate axial length of the adult eye?
24mm
145
Which is the most anterior angle structure?
Schwalbe's line
146
Which is the most posterior angle structure?
Iris
147
Which layer of the eye is considered avascular?
Sclera
148
Which areas of the eye have non-fenestrated capillaries?
Iris
| Retina
149
Which areas of the eye have fenestrated capillaries?
Ciliary body
| Choroid
150
What can pass through the tight junctions of non-fenestrated capillaries?
Water
| Small ions
151
What nerves supply the cornea?
Long ciliary nerves
Short ciliary nerves
-both are branches of V1
152
Where do corneal nerves enter the cornea?
Mid-stromal region
153
Which layer of the cornea is devoid of nerve supply?
Descemet's membrane
154
Why type of nerve endings are found in the cornea?
Open ended
| AKA nocioreceptors
155
What is the approximate volume of the orbit?
30 cc
| -Globe is 6.5cc
156
About what percent of the orbit is occupied by the globe?
22%
157
What is the purpose of the Valve of Hasner?
To prevent nasal cavity fluid from entering the nasolacrimal system
158
Where is the lacrimal gland located?
In a fossa of the frontal bone
159
What types of tears does the lacrimal gland shed?
Reflex tearing
| Emotional tearing
160
What glands shed maintenance tears?
Accessory lacrimal glands
161
A 45 y/o man has a loss of corneal sensation, cannot abduct, and tilts his head to his left shoulder as you examine him. No facial asymmetry is found, nor are there hearing difficulties. Where is the site of the lesion?
Cavernous sinus
| -Symptoms stem from affected CNs IV, V1 and VI
162
Macular sparing homonymous hemianopsias are often the result of what?
Stroke
163
What two arteries supply the macula?
Middle cerebral artery
| Posterior cerebral artery
164
A cuneus gyrus lesion would give what VF defect in the macula?
Inferior VF defect
| -That is where superior fibers terminate
165
A temporal lobe lesion would yield what VF defect?
"Pie in the sky"
166
A parietal lobe lesion would yield what VF defect?
"Pie on the floor"
| -You "Par(ietal)ty on the floor)
167
Which fibers would medial in the left optic tract?
Ipsilateral superior temporal
| Contralateral superior nasal
168
Superior fibers in the optic tract always go which way?
Medial
169
Inferior fibers in the optic tract always go which way?
Lateral
170
Which optic nerve fibers never cross?
Temporal fibers
171
The left optic tract carries what fibers?
Ipsilateral temporal fibers
Contralateral nasal fibers
Contralateral nasal macular fibers
172
Which region of the optic nerve head do the superior temporal retinal fibers occupy?
Superior pole
173
Vision loss from anterior AION results from lack of blood flow through which arteries?
Short posterior ciliary arteries (SPCA)
174
Where is the thickest region of rods in the retina?
Just outside the perifovea - 5mm outside the foveola
175
Which region of the macula has the thickest region of ganglion/bipolar cells?
Parafovea
176
What do neuroglial cells do?
Glycogen metabolism - providing nutrients to the retina
Immunological activities - some are phagocytic
Provide structure, support, and protection
177
The central retinal artery forms 2 capillary networks within the inner retina. Where are they located?
In the inner nuclear layer (INL)
178
Where does the first synapse occur in the visual pathway?
Outer plexiform layer
179
What is the only layer in the retina that receives blood from the central retinal artery and the choriocapillaris?
Outer plexiform layer
180
Where are the cell bodies for rods/cones located?
Outer nuclear layer
181
In what layer of the retina are amacrine, bipolar and horizontal cells found?
Inner nuclear layer (INL)
182
What are the layers of the retina?
```
-RPE, 2 outer, 2 inner, GNI
RPE
PRs
External limiting
ONL - cell body of PRs
OPL
INL - cell body of bipolar cells
IPL
GCL - cell body of ganglion cells
NFL
Inner limiting membrane
```
183
The RPE has a tight association with what?
Choroid
184
RPE is derived from what?
The outer layer of the optic cup
185
What fibers do the fetal nucleus originate from?
Secondary fibers
186
Which layer of the lens contains the most crystallins?
Embryonic nucleus
187
Which layer of the lens has the highest index of refraction?
Embryonic nucleus - because of all the crystallins
188
Which layer of the lens contains the Y sutures?
Fetal nucleus
189
What is Henle's fiber layer?
The outer plexiform layer (OPL) in the foveola
190
Where does CSF flow within the optic nerve?
Between the pia and arachnoid mater
191
What is the most common cause of unilateral proptosis?
Hyperthyroidism - it is the number one cause of both unilateral and bilateral proptosis
192
What is a distinctive sign of a carotid cavernous fistula?
Pulsatile proptosis
193
Which nerve is responsible for swallowing, and posterior 1/3 taste?
Glossopharyngeal
194
CN 9 - glossopharyngeal innervates which salivary gland (among other things)?
Parotid - allows salivation
195
A 40 y/o male reports sudden onset metamorphopsia OD. He had a similar episode about 5 years earlier that "drove him crazy" because it lasted about 3 months. What is the most likely diagnosis?
Central Serous Retinopathy (CSR)
196
What is the most distinctive FA pattern in CSR?
Smokestack appearance
197
What are the common signs/symptoms of Phthiriasis palpebarum?
Severe Itching
Pinpoint blood-tinged debris along eyelash margins
Inflamed eyelash margins (but no meibomitis)
198
What is Phiriasis palpebarum?
Lice
199
What is madarosis?
Loss of eyelashes
200
What is the most common etiology for orbital cellulitis?
Extension of a current paranasal sinus infection
201
What is the main cause of a conjunctival melanoma?
Primary acquired melanosis
202
What is the most common etiology of conjunctival squamous cell carcinoma?
Conjunctival intraepithelial neoplasia (CIN)
203
What is the typical demographic for squamous cell carcinoma?
Elderly
Caucasian
Males
204
What stain is helpful in the diagnosis of squamous cell carcinoma?
Rose bengal
205
Where does a conj squamous cell carcinoma most commonly arise?
At the limbus - with a feeder vessel
206
A carcinoma is a cancer of what?
Epithelial tissue
207
A sarcoma is a cancer of what?
Connective tissue
208
Which corneal dystrophy is not autosomal dominant?
Macular distrophy (AR)
209
What is the typical demographic of Fuch's endothelial dystrophy?
Signs at age 30-40
Symptoms at age 40-50
Female
Often inherited (AD)
210
What are the common early symptoms of Fuch's?
Glare
| Light sensitivity
211
What are the common later symptoms of Fuch's?
```
Pain (because of bullae)
Decreased VA (corneal edema)
```
212
What are some early signs/symptoms of Terrien's marginal dystrophy?
```
Blurred vision (high astigmatism)
Haze in corneal periphery (slowly progresses to circumlimbal peripheral corneal thinning)
```
213
What is scleromalacia perforans?
Necrotizing scleritis without inflammation
214
Scleromalacia perforans is associated with what systemic disease?
Rheumatoid arthritis
215
What is the worst form of scleritis?
Necrotizing with inflammation
216
Choroidal melanomas typically arise from what?
Choroidal nevus
217
What is the most common primary intraocular tumor in adults?
Choroidal melanoma
218
What are the most common secondary causes of ocular cancer in males and females?
Males - Lung cancer
| Females - breast cancer
219
Choroidal melanomas are more common in which demographic?
Caucasians
220
What are 3 risk factors for increased progression from dry to wet AMD?
Focal hyperpigmentation
Smoking
Soft drusen
221
What is the most likely location for a retinal tear?
Superior temporal
222
What are 2 common causes of exposure keratopathy?
Thyroid eye disease
| Ectropion
223
Name 3 conditions that can cause a mucous tear film deficiency.
Ocular pemphigoid
Steven Johnson's syndrome
Vitamin A deficiency
224
What is a common ocular complication of Ehler's Danlos syndrome?
Lens subluxation
225
Ehler's Danlos syndrome is a disorder of what?
Connective tissue
226
Why is vitamin A deficiency one of the leading causes of blindness in 3rd world countries?
Causes keratinization of the cornea and conj
227
What is the most common cause of dacryocystitis?
Blockage of the nasolacrimal duct
228
What things are associated with microcornea?
HVID less than 10mm
Hyperopia
Glaucoma
AD or AR inheritance
229
What things are associated with megalocornea?
HVID over 13mm
X-linked inheritance
Associated with myopia
230
What is the buzz-word for Salzmann's nodular degeneration?
Blue-gray stromal opacities
| Unilateral
231
What are the 4 common etiologies for Salzmann's?
Dry eye
Trachoma
Phlyctenulosis
Interstitial keratitis
232
A patient who has suffered what is at higher risk for RCE?
Corneal abrasion
233
What are the two main etiologies that increase the risk of RCE?
```
Corneal abrasion
Corneal dystrophies (Mainly EBMD)
```
234
Retinoschisis is most common in what two retinal locations?
Inferior-temporal
| Superior-temporal
235
What is the inheritance characteristic of juvenile retinoschisis?
X-linked
236
What is the age classification of a premature baby?
Less than 36 weeks
237
What is the most common, benign orbital tumor in adults?
Cavernous hemangioma
238
Where do cavernous hemangioma usually arise?
Directly behind the eye, in the circle of Zinn
239
What is a common sequelae of a cavernous hemangioma?
Progressive, unilateral proptosis
240
What is the most common, benign orbital tumor in kids?
Capillary hemangioma
241
What are the 2 common culprits of Ocular Ischemic Syndrome (OIS)?
Atherosclerosis - most common
| Giant cell arteritis
242
What is the typical presentation of OIS?
Periorbital pain
Gradual VA loss
Unilateral
Midperipheral hemes
243
What is the most likely etiology of a cavernous sinus thrombosis?
Nasal infection
| -Or any infection around the nose or eye
244
What bacteria is the most common culprit causing a cavernous sinus thrombosis?
Staph aureus
245
Which causes a higher risk of neovascular glaucoma: CRVO or BRVO?
CRVO
246
What are the two main risk factors in retinal vein occlusions?
HTN
| DM
247
What is the most common cause of retinal vascular occlusive disease?
Branched retinal vein occlusion
248
Which corneal layer has the most mitochondria?
Endothelium
| - NaK pump uses a lot of energy
249
What are the average horizontal and vertical dimensions of the ONH?
H: 1.5mm
V: 1.75
250
What two arteries supply blood to the ONH?
Short posterior ciliary arteries
| Central retinal artery - minor contributor
251
Which portion of the optic nerve has some attachments with EOMs, and causes pain during eye movements in optic neuritis?
Intraorbital
252
What are the 4 portions of the optic nerve, and their approximate lengths?
Intraocular - 1mm
Intraorbital - 30mm
Intracanalicular - 6-10mm
Intracranial - 10-16mm
253
What does the optic nerve consist of?
Axons of ganglion cells
254
How many axons of ganglion cells are found in a typical optic nerve?
1.0 - 1.2 million
255
The infraorbital nerve is a branch of what nerve?
V2
256
What bone does the optic foramen pass through?
Lesser wing of the sphenoid
257
What is another name for the ethmoid bone in the medial wall?
Lamina papyracea
258
Which orbital wall does not utilize the sphenoid bone?
Floor
259
What are the 7 bones of the orbit?
```
Frontal
Sphenoid
Ethmoid
Lacrimal
Maxilla
Palatine
Zygomatic
```
260
How many cells thick is the corneal endothelium?
1 cell
261
What is the main function of the corneal endothelium?
Use NaK pump to remove fluid from the cornea, back into the aqueous
262
What is the correct order of these muscles from superior to inferior: Superior oblique, Superior levator palpebrae, Superior rectus.
Superior levator palpebrae
Superior rectus
Superior oblique
263
When does the eye reach maximum size?
Puberty
264
What is the function of the vortex veins?
Drain the choroid, ciliary body, and iris (vascular tunic)
265
How many vortex veins are there per eye?
4-7
266
Muller's muscle is innervated by what nervous system?
Sympathetic
