Module 1 - Ocular Anatomy: Orbit, Ocular, Adnexa and Eyeball Flashcards
(324 cards)
1
Q
Describe the medial walls and lateral walls of the orbit
A
Medial walls are parallel to each other, separated by the ethmoidal and sphenoidal sinuses
Lateral walls forms a 45 degree angle with the medial wall
2
Q
What is the volume of the orbit as well as its height, width and diameter?
A
Volume: 30 cc
Height: 35 mm
Width: 45 mm
Diameter: 40-45 mm
3
Q
These are bony cavities which contain the eye and “pear shaped” with the optic nerve representing its stem
A
Orbit
4
Q
What are the 7 bones that make up the orbit?
A
Frontal, zygomatic, maxillary, ethmoidal, sphenoidal, lacrimal, palatine
5
Q
What are the roofs of the orbit and its content?
A
Orbital plate of the frontal bone which contains the lacrimal gland fossa
Lesser wing of the sphenoid which contains the optic canal
6
Q
Distance of fovea trochlearis to the orbital margin
A
4 mm
7
Q
It serves as the pulley for the superior oblique muscle
A
Fovea trochlearis
8
Q
Components (bone) of the medial orbital wall
A
Maxillary bone
Lacrimal bone
Ethmoidal bone
Lesser wing of the sphenoid
9
Q
What does the medial orbital wall contains?
A
Nasolacrimal canal and lacrimal sac
10
Q
The medial orbital wall is described as paper thin medial wall known as?
A
Lamina papyracea
11
Q
The lateral wall of the orbit is formed by?
A
Zygomatic bone
Greater wing of the sphenoid
12
Q
Wall of the orbit described as the thickest and strongest
A
Lateral wall of the orbit
13
Q
What are the 4 sites of attachment for the lateral orbital tubercle?
A
Check ligament of lateral recuts muscle
Suspensory ligament of the eyeball
Lateral palpebral ligament
Aponeurosis of the levator ligament
14
Q
It served as the roof of the maxillary sinus
A
Floor of the orbit
15
Q
The floor of the orbit is made up of what 3 bones?
A
Maxillary bone (blow-out fractures)
Palatine bone
Orbital plate of zygomatic bone
16
Q
It contains the infraorbital groove leading to the infraorbital foramen
A
Floor of the orbit
17
Q
What muscle arises from the orbital floor and the only extraocular muscle that does not originate at the orbital apex?
A
Inferior oblique muscle
18
Q
Where is the entry portal for all nerves and vessels?
A
Orbital apex
19
Q
Where is the site of origin for all extraocular muscles except the inferior oblique?
A
Annulus of zinn
20
Q
It contains the superior orbital fissure
A
Orbital apex
21
Q
What are the 2 nerves located laterally (outside the Annulus of Zinn?
A
Lacrimal and frontal branch of CN V
Trochlear nerve CN IV
22
Q
What are the 4 nerves/vessels located medially (within the Annulus of Zinn)?
A
Superior and inferior divisions of CN III
Nasociliary branch of CN V
Abducens nerve (CN VI)
Superior ophthalmic vein
23
Q
What are the 2 nerves/veins in the inferior orbital fissure?
A
Maxillary and pterygoid parts of CN V
Inferior ophthalmic vein
24
Q
Under the orbital apex is the optic canal which contains what artery and nerve?
A
Optic nerve
Ophthalmic artery
25
What is the main blood supply of the orbit?
Ophthalmic artery (1st major branch of the intracranial ICA)
26
What are the 5 major branches of the ophthalmic artery?
```
Central retinal artery
Lacrimal artery
Muscular branches of the extraocular muscles
Medial palpebral arteries
Posterior ciliary arteries
```
27
Describe the course of the central retinal artery
It enters the optic nerve 8-15 mm behind the globe
28
What are the 2 structures that the lacrimal artery supplies?
Lacrimal gland
| Upper eyelids
29
What artery does the muscular branches of the extraocular muscles gives off?
Anterior ciliary artery
30
What structures do the anterior ciliary artery supplies?
```
Anterior sclera
Episclera
Limbud
Conjunctiva
Contributes to the major arterial circle of the iris
```
31
What structure does the medial palpebral arteries supplies?
Eyelids
32
What are the 2 branches of the posterior ciliary arteries?
Long posterior ciliary arteries
| Short posterior ciliary arteries
33
What does the long posterior ciliary arteries supply?
Ciliary body
34
Describe the course of the long posterior ciliary arteries
Anastomose with each other to form the major arterial circle of iris
35
What are the 2 structures that the short posterior ciliary arteries supply?
Choroid
| Optic nerve head
36
What are the 2 veins responsible for the venous drainage?
Superior and inferior ophthalmic vein
37
What are the 3 veins to which the superior and inferior ophthalmic veins drain?
Vortex vein
Anterior ciliary vein
Central retinal vein
38
What sinus does the superior and inferior ophthalmic veins communicate?
Cavernous sinus
39
What is this outer structure that protects the eyeball?
Eyelid
40
The eyelid has this gland that lubricates the eye surface which is located within the tarsus
Meibomian glands
41
The lids come together from where?
Medial and lateral canthi
42
What is this space between two open lids?
Palpebral fissure
43
The upper lid normally covers how many millimeters of the superior limbus?
2 mm
44
At what level does the lower lid placed?
At the level of the inferior limbus
45
What is this exposed zone between the upper and lower eyelids?
Interpalpebral fissure
46
What is the measurement of the interpalpebral fissures in adults?
27 mm long and 8-11 mm wide
47
Which is more mobile, the upper eyelid or the lower eyelid?
Upper eyelid
48
The upper eyelid can be raised by how many millimeters by the levator?
15 mm
49
What are the 9 anatomical segments of the eyelid?
```
Skin
Margin
Subcutaneous connective tissue
Orbicularis oculi muscle
Orbital septum
Levator muscle
Tarsus
Mueller's muscle
Conjuctiva
```
50
What is the thinnest anatomical segment of the eyelid?
Skin
51
It is due to insertion of levator aponeurosis near the upper border of the tarsus (may not be present in Asians)
Eyelid fold
52
What is the anatomical segment of the eyelid that has no fat content and may swell due to fluid accumulation or hemorrhage?
Subcutaneous connective tissue
53
What is the anatomical segment of the eyelid that is considered as the punctum?
Lid margin
54
This line corresponds histologically to the most superficial part of the orbicularis oculi muscle
Gray line
55
The lid margin has a "gray line" that corresponds histologically to the most superficial part of the orbicularis oculi muscle known as what muscle?
Muscle of Riolan
56
What structure arises anteriorly from the gray line?
Eyelashes
57
What structure arises posteriorly to the gray line?
Meibomian gland (within the tarsus)
58
What anatomical segment of the eyelids that is arranged in a concentric band around the interpalpebral fissure?
Orbicularis oculi muscle
59
What are the 2 parts of orbicularis oculi?
Orbital
| Palpebral
60
What 3 structures does the orbital part of the orbicularis oculi muscle inserts to?
Medial canthal tendon
Orbital rim
Corrugator supercili muscle
61
What part of the orbicularis oculi has a sphincter like control and is voluntarily controlled?
Orbital part
62
What part of the orbicularis oculi that is voluntary or involuntary (for normal and reflex blinking)?
Palpebral part
63
What anatomical segment of the eyelid that has extension of the periosteum of the root and floor of the orbit?
Orbital septum
64
Where does the orbitL septum attaches to?
Anterior surface of the levator muscle
65
What is the function of the orbital septum?
Barrier to spread or blood or inflammation
66
What anatomical segment of the eyelid that originates from a tendon that blends with the superior rectus and superior oblique muscles at the apex of the orbit?
Levator muscle
67
The levator muscle divides into what 2 structures?
Levator aponeurosis
| Superior tarsal muscle (Mueller's muscle)
68
Mueller's muscle is known as what muscle?
Superior tarsal muscle
69
What is the function of the levator aponeurosis?
Produces the eyelid fold
70
What cranial nerve innervates the superior tarsal muscle?
Superior division of CN III
71
What is the function of the superior tarsal muscle?
Elevates the eyelid
72
What anatomical segment of the eyelid consist of dense connective tissue not cartilage?
Tarsus
73
The tarsus is attached to what structure and by what 2 ligaments?
Attached to the Orbital margin by the Medial and Lateral palpebral ligaments
74
What gland is a modified holocrine gland which is the oily layer of the tear film?
Meibomian gland
75
The facial system is derived from what artery?
ECA
76
The facial system gives rise to what artery and is considered to be an important landmark in DCR surgery?
Angular artery
77
What are the 2 systems involved in the venous drainage of the eyelid?
Superficial/pretarsal system
| Deep/post-tarsal system
78
The superficial/pretarsal system drains to what 2 veins?
Internal and external jugular veins
79
The deep/post-tarsal system drains to what structure?
Cavernous sinus
80
What are the 2 accessory eyelid structures?
Pilica semilunaris
| Caruncle
81
What is this accessory eyelid structures described as narrow, highly vascularized, crescent-shaped fold of conjunctival tissue?
Plica semilunaris
82
What type of cells is plica semilunaris rich in?
Goblet cells
83
What structure is plica semilunaris analogous?
Nictating membrane
84
What accessory eyelid structure described as small, fleshy, ovoid structure?
Caruncle
85
What accessory eyelid structure that contains sebaceous glands and fine colorless hairs?
Caruncle
86
Where is the lacrimal gland situated?
Frontal bone
87
What are the 2 parts of the lacrimal gland?
Palpebral gland
| Orbital gland
88
The 2 parts of the lacrimal gland is divided by what structure?
Levator aponeurosis
89
The palpebral and orbital gland may occasionally be connected by what structure?
Isthmus
90
What gland is an exocrine gland and produces a serous secretion?
Lacrimal gland
91
What are the 2 types of cells found in the lacrimal gland?
Acinar cells
| Myoepithelial cells
92
What cell found in the lacrimal gland that lines the lumen?
Acinar cells
93
What cell found in the lacrimal gland that surrounds the parenchyma?
Myoepithelial cells
94
What is the blood supply of the lacrimal gland?
Lacrimal artery
95
Where does the accessory glands located?
Eyelids
96
What 2specific glands in the accessory gland that produce basal tear secretion?
Glands of Krause and Wolfring
97
What are the 6 structures of the lacrimal excretory system?
```
Lacrimal punctum
Upper and lower canaliculi
Common canaliculus
Nasolacrimal sac
Nasolacrimal duct
```
98
What are the 4 characteristics of a tear film?
Provides a smooth optical surface at the air-eye interface
Serves as a medium for removal of debris
Supply oxygen to the cornea
Protective (antimicrobial and lubricating properties)
99
What are the "tri-laminar" structures of the tear film?
Anterior, lipid layer
Middle, aqueous layer
Posterior, glycoprotein layer
100
What tri-lamimar structure of the tear film that comes from the meibomian glands?
Anterior layer, lipid layer
101
How many glands are found in the upper and lower lid?
30-40 in the upper lid
| 20-30 in the lower lid
102
What are the 4 functions of the anterior layer of the tear film?
Optical clarity
Hydrophobic barriers (prevents overflow)
Slows down evaporation
Lubrication
103
What tri-laminar layer consists of electrolytes and proteins?
Middle, aqueous layer
104
The middle layer of the tear film is secreted by what 3 structures?
Main lacrimal glands
| Accessory lacrimal glands of Wolffring and Krause
105
What is the 4 functions of the middle, aqueous layer of the tear film?
Supplies oxygen
Antibacterial
Smoothens minor irregularities
Washes away debris
106
What cells/structures do the posterior, glycoprotein layer is secreted?
Conjunctival goblet cells
| Accessory lacrimal glans of Henle and Manz
107
What characteristic of the posterior, glycoprotein layer allows better stability of the tear film layer?
Lowers surface tension
108
What tri-laminar layer converts the epithelium from hypdrophobic to hydrophilic which allows for even distribution of tears?
Posterior, glycoprotein layer
109
What are the 4 recti muscles?
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
110
What are the 2 oblique muscles?
Superior oblique
| Inferior oblique
111
Origin, insertion, blood supply and size of medial rectus
Origin - annulus of zinn
Insertion - medially, 5.5 mm from limbus
Blood supply - inferior muscular branch of ophthalmic artery
Size - 40.8 mm long, 1.3 mm wide
112
Origin, insertion, blood supply and size of inferior rectus
Origin - annulus of zinn
Insertion - inferiorly, 6.5 mm from limbus
Blood supply - inferior muscular branch of ophthalmic artery and infraorbital artery
Size - 40 mm long, 9.8 mm wide
113
Origin, insertion, blood supply and size of lateral rectus
Origin - annulus of zinn
Insertion - laterally, 6.9 mm from limbus
Blood supply - lacrimal artery
Size - 40.6 mm long, 9.2 mm wide
114
Origin, insertion, blood supply and size of superior rectus
Origin - annulus of zinn
Insertion - superiorly, 7.7 mm from limbus
Blood supply - superior muscular branch of ophthalmic artery
Size - 41.8 mm long, 10.6 mm wide
115
Origin, insertion, blood supply and size of superior oblique
Origin - annulus of zinn
Insertion - to trochlear at orbital rim, then inferior and under superior rectus
Blood supply - superior muscular branch of ophthalmic artery
Size - 40.0 mm long, 10.8 mm wide
116
Origin, insertion, blood supply and size of inferior oblique
Origin - orbital floor
Insertion - posterior, inferior temporal quadrant at the level of the macula
Blood supply - inferior branch of ophthalmic and infraorbital artery
Size - 37 mm long, 9.6 mm wide
117
What is the blood supply of the extraocular muscles?
Muscular branches of the ophthalmic artery
118
What is blood supply of the lateral rectus?
Lacrimal artery
119
What is the blood supply of the inferior oblique?
Infraorbital artery
120
What structures do the CN III innervates?
Superior, medial, inferior rectus muscles and the inferior oblique
121
What structures do CN IV innervates?
Superior oblique
122
What structures do the CN VI innervates?
Lateral rectus
123
What is this thin, transparent vascular tissue?
Conjunctiva
124
What are the 3 zones of the conjunctiva?
Palpebral conjunctiva
Bulbar conjunctiva
Forniceal conjunctiva
125
What zone of the conjunctiva lines the inner aspect of the eyelids?
Palpebral conjunctiva
126
What zone of the conjunctiva covers the sclera?
Bulbar conjunctiva
127
What zone of the conjunctiva is where the fornix (junction of the palpebral and bulbar conjunctiva) located?
Forniceal conjunctiva
128
What is the vascular supply of the conjunctiva?
Anterior ciliary artery
129
What nerve innervates the conjunctiva?
1st division of CN V (ophthalmic division)
130
What are the 2 structures of the conjunctiva?
Conjunctival epithelium
| Conjunctival stroma
131
Describe the layer and epithelial lining of the conjunctival epithelium
2-5 layers of stratified columnar epithelial cells
132
What cells of the conjunctival epithelium contains mucous secreting Goblet cells?
Superficial epithelial cells
133
What cells of the conjunctival epithelium contains pigment?
Basal epithelial cells
134
What are the layers of the conjunctival stroma?
Adenoid layer
| Fibrous layer
135
What layer of the conjunctival stroma that consists of the lymphoid tissue and dose not develop until 2nd or 3rd month of life?
Adenoid layer
136
What layer of the conjunctival stroma that contains connective tissue?
Fibrous layer
137
Where is the accessory lacrimal glands mostly found?
Lower fornix
138
What structure is a fibrous membrane that envelops the eye from limbus to the optic nerve?
Tenon's capsule
139
Tenon's capsule contributes to what ligament?
Check ligaments
140
The tenon's capsule forms what ligament?
Lockwood ligament
141
Describe the contributions of the tenon's capsule to the check ligament
Tubular reflections of the tenon's capsule over the EOM's
| Limits action of the EOM's
142
Describe how the tenon's capsule forms the lookwood's ligament
Suspensory ligament of the globe
| Formed by the fusion of the tenon's with the fascia of the inferior rectus and the inferior oblique
143
What structure is a fine, thin, elastic layer which covers the sclera?
Episclera
144
What structure contains numerous blood vessels which provides nourishment for the sclera?
Episclera
145
What is the thick outer coat of the eye?
Sclera
146
Normally, what is the characteristics of the sclera?
White and opaque
147
What structure becomes red and in inflammatory and infectious conditions?
Sclera
148
What structure is avascular, fibrous, outer, protective coating of the eye?
Sclera
149
Describe the course of the sclera anteriorly and posteriorly
Continuous with the cornea anteriorly and with the dural sheath posteriorly
150
What structure is scleral fibers that pass through e optic nerve and acts like a sieve?
Lamina cribosa
151
What is the thickness of the sclera where the EOM's insert and elsewhere?
0.3 mm thick where the EOM's insert and about 1 mm thick elsewhere
152
The sclera is composed of what cells/substances?
Bundles of collagen, fibroblasts and ground substance
| Unlike cornea, contains more water and fibers are less uniformly arranged
153
What is the transparent front "window" of the eye?
Cornea
154
What is considered to be the major refractive surface of the eye?
Cornea
155
What structure loss of transparency in infectious and inflammatory diseases?
Cornea
156
Why is that cornea is considered to be the main refractive element of the eye (43D)?
More curved posteriorly than anteriorly
157
Cornea's transparency is secondary to what 3 characteristics?
Uniform structure
Avascularity
Deturgescence
158
Describe the 3 dimensions of an average adult cornea
0. 54 mm at the center (more spherical in shape)
0. 65 mm at the periphery (flatter)
11. 5 mm in diameter
159
What are the 5 layers of the cornea?
```
Epithelium
Bowman's membrane
Stroma
Descemet's membrane
Endothelium
```
160
Cornea is nourished by what 2 structures?
Precorneal tear film layer which provides oxygen to the epithelium
Aqueous humor which provides glucose to the stroma and epithelium
161
How many layers of the corneal epithelium?
5-6 layers
162
What 3 type of cells that are found in the corneal epithelium?
Basal columnar cells
Polygonal cells ("wing cells")
Nonkeratinized stratified squamous cells from the superficial layer
163
What cells are also known as "wing cells"?
Polygonal cells
164
What cells in the corneal epithelium is present in the superficial layer?
Nonkeratinized stratified squamous cells
165
The corneal epithelium is attached by what structures?
Hemidesmosomes
166
What is the characteristic of the cornea epithelium that is due to its lipid content?
Hydrophobic
167
What structure of the cornea that is acellular, therefore, cannot regenerate after injury?
Bowman's membrane/layer
168
What structure of the cornea that opacifies or forms a scar after injury?
Bowman's membrane/layer
169
What structure of the cornea serves as a barrier to most molecules?
Bowman's membrane/layer
170
What structure of the cornea contributes to 90% of the corneal thickness?
Stroma
171
What cells/substances composed the cornea that makes it optically clear?
Fibroblasts (keratinocytes)
| Ground substance and collagen lamellae (uniformly arranged and avascular)
172
What is the characteristic of the stroma in the cornea that allows for its optical clarity?
Regular arrangement of the collagen fibers in the stroma
173
How many percentage of the light that is transmitted by the cornea?
98%
174
What structure of the cornea known to be the basement membrane of the corneal endothelium?
Descemet's membrane
175
What are the metabolic by-products of the Descemet's membrane and peripherally located?
Hassal-Henle bodies
176
What is the central excresences of the cornea which look like bubbles in the central cornea?
Corneal Guttata
177
What happens in Fuch's Endothelial Dystrophy?
Endothelial cell loss leading to loss of visual acuity
178
What is the embryonal origin of the corneal epithelium?
Neural crest (neuroectodermal in origin)
179
The corneal endothelium is composed of how many layer and what type of cells?
Single layer of hexagonal cells
180
The apex of the corneal endothelium faces what structures?
Anterior chamber
181
The base of the corneal endothelium is attached to what structure?
Descemet's membrane
182
How many hexagonal cells in the corneal endothelium are diminished as we age?
1 million cells at birth
183
What are the 2 functions of the corneal endothelium?
Barrier between the stroma and the aqueous
| Pump to maintain the cornea in a partially dehydrated state
184
What are the 3 fates of the corneal endothelium when subjected to injury from either surgery, raised IOP or disease?
Corneal decompensation
Edema
Clouding of the cornea
185
What is the junction between the cornea and sclera?
Limbus
186
What condition is the whitening of the limbus as part of old age?
Arcus senilis
187
What condition is often mistaken as cataract?
Arcu senilis
188
What is the importance of the limbus?
Surgical landmark
189
What are the 5 structures that are included in the limbus?
```
Conjunctiva
Tenon's capsule
Episclera
Corneoscleral stroma
Aqueous outflow apparatus
```
190
What are the 10 internal ocular structures?
```
Anterior chamber
Iris
Lens
Ciliary body
Posterior chamber
Vitreous cavity
Retina
Macula
Choroid
Optic disc
```
191
What is the space between the cornea and iris?
Anterior chamber
192
What is the watery fluid found in the anterior chamber?
Aqueous humor
193
Normally, is the anterior chamber cellular or acellular?
Acellular
194
Presence of cells in the anterior chamber indicates what conditions?
Infectious
| Inflammatory
195
What are the 5 important structures of the anterior chamber?
```
Schwalbe's line
Schlemn's canal and the trabecular meshwork
Scleral spur
Anterior border of the ciliary body
Iris
```
196
What structure of the anterior chamber that marks the termination of the corneal endothelium?
Schwalbe's line
197
What structure drains the aqueous from the anterior chamber?
Schlemn's canal and the trabecular meshwork
198
What structure of the anterior chamber that has inward extension of the sclera between the ciliary body and Schlemn's canal?
Sclera spur
199
What structure of the anterior chamber is the iris and ciliary body attached?
Scleral spur
200
What is the middle, vascular layer of the eye?
Uveal tract
201
What structure contributes to the blood supply of the retina?
Uveal tract
202
What 3 structures comprise the uveal tract?
Iris
Ciliary body
Choroid
203
What structure is the anterior extension of the ciliary body?
Iris
204
What is the colored part of the eye that screens the light?
Iris
205
What structure is the pigmented posterior surface?
Iris
206
What structure accounts for the variety of eye colors seen?
Iris
207
The variety of colors seen by the iris is dependent on the amount of what substance?
Pigment
208
The iris is composed of:
Blood vessels
Connective tissue
Melanocytes
Pigment cells
209
What 2 muscles are found in the iris stroma?
Dilator muscle
| Sphincter muscle
210
Dilation of the pupillary size is due to the sympathetic or parasympathetic activity?
Sympathetic activity
211
Constriction of the pupils is due to sympathetic or parasympathetic activity?
Parasympathetic activity
212
What cranial nerve is responsible in constricting the pupils?
CN III
213
What is the blood supply of the iris?
Major circle of the iris
214
Describe the major circle of the iris
Non-fenestrated endothelium (do not leak flourescein on angiography)
215
What is the sensory innervation of the iris?
Ciliary nerves
216
What is the circular opening at the center of the iris?
Pupil
217
What structure adjusts the amount of light entering the eye?
Pupil
218
What determines the size of the pupils?
Parasympathetic and sympathetic innervation of the iris
219
What structure of the eye that produces the aqueous humor?
Ciliary body
220
What happens with accommodation?
Changes in tension leading to increased thickness of the lens
221
Describe accommodation
Allows eye to focus at near objects
222
What structure extends from the anterior end of the choroid to the root of the iris (6 mm)?
Ciliary body
223
What are the 2 parts of the ciliary body?
Pars plicata
| Para plana
224
What is the part of the ciliary body that is the anterior corrugated zone?
Par plicata
225
What structure of the pars plicata that produces the aqueous humor?
Ciliary processes
226
What part of the ciliary body that is flattened, posterior zone?
Pars plana
227
The ciliary body is lined by what 2 layers?
Internal non-pigmented layer
| External pigmented layer
228
What lining of the ciliary body that represents the anterior extension of the neuroretina?
Internal non-pigmented layer
229
What lining of the ciliary body that represents the extension of the retinal pigment epithelium?
External pigmented layer
230
What structure of the ciliary body that composed of longitudinal, circular and radial muscles?
Ciliary muscle
231
What structure of the ciliary body that contracts and relaxes the zonular fibers?
Circular muscles
232
What 2 events happen when the circular muscle is stimulated?
Alters the tension on the capsule of the lens
| Allows the lens to give variable focus for distance and near
233
What structure of the ciliary body that inserts into the trabecular meshwork (to vary pore size)?
Longitudinal muscles
234
What is the vascular, pigmented layer between the sclera externally and retina internally?
Choroid
235
What provides blood supply to the outer retinal layers?
Choroid
236
What part of the retina is nourished by the choroid?
Outer retina
237
What are the 3 layers of blood vessels of the choroid?
Innermost/choroicapillaries
Middle layer
Outer layer
238
What layer of the choroid that has fenestrated characteristic?
Innermost/choroicapillaries
239
What are the 3 blood supply of the choroid?
Long posterior ciliary arteries
Short posterior ciliary arteries
Recurrent branches of the anterior ciliary arteries
240
What veins drain the choroid?
Vortex veins
241
What structure of the choroid that is bound internally?
Bruch's membrane
242
What structure of the choroid that is bound externally?
Sclera
243
What are the 5 elements of the Bruch's membrane?
Basal lamina of the retinal pigment epithelium
Inner collagenous zone
Porous elastic fibers
Outer collagenous zone
Basal lamina of the outer layer of the choriocapillaries
244
Defects of Bruch's membrane may arise from what 4 possible conditions?
Myopia
Pseudoxanthoma elasticum
Trauma
Inflammation
245
Defects of the Bruch's membrane leads to the formation of what structure?
Formation of subretinal neovascular membrane
246
What structure is bound externally by the choroid?
Sclera
247
What is the space between the choroid and the sclera?
Suprachoroidal space
248
What is the shape of the lens?
Biconvex
249
What structure is second of 2 refractive elements?
Lens
250
What structure is weaker than the cornea (1/3 of the total refractive power of the eye)?
Lens
251
What is the measurement of the lens anterosterior and equatorial diameter?
Anteroposterior: 4.0 - 5.0 mm
| Equatorial diameter: 9.0 - 10 mm
252
What are the 3 compositions of the lens (with the percentage)?
65% water
35% protein (highest protein content of any tissue in the body)
Trace minerals (Na, Cl, K, ascorbic acid, glutathione)
253
Lens thickness changes during what process?
Accommodation
254
What are the 2 structures that nourish solely the lens?
Aqueous
| Vitreous
255
The lens is enclosed by what structure?
Capsule
256
Describe the Capsule of the lens
Semi-permeable membrane
Product of the lens epithelium
Anterior capsule is 2x thicker than the posterior capsule
257
What structure holds the lens in place?
Zonule of Zinn
258
What does the Zonule of Zinn composed of?
Fibrils
259
Where does the Zonule of Zinn arise from?
Ciliary body
260
Where does the Zonule of Zinn inserts?
Lens equator
261
What is the small space behind the iris and in front of the vitreous?
Posterior chamber
262
The posterior chamber is filled with what fluid?
Aqueous humor
263
The posterior chamber is normally cellular or acellular?
Acellular
264
What is the large space behind the lens?
Vitreous cavity
265
The vitreous cavity extends to what structure?
Retina
266
What is the volume of vitreous cavity?
Approximately 4.5 cc
267
Describe the vitreous humor
Transparent gel-like material
268
What fluid is filled in the vitreous cavity?
Vitreous humor
269
What are the characteristics of the vitreous?
Clear, avascular, gelatinous body
Comprises 2/3 of the volume of the eye
99% water, 1.0% collagen and hyaluronic acid
Involved in metabolism which is the passageway for metabolites used by the lens, ciliary body and retina
270
What is the outer surface of the vitreous?
Hyaloid membrane
271
The hyaloid membrane is in contact with what 5 structures?
```
Posterior capsule
Zonules
Pars plana
Retina
Optic nerve head
```
272
What structure is where the vitreous is firmly attached to the retina?
Vitreous base
273
What condition involved in the separation of the vitreous from the inner retina?
Posterior vitreous detachment
274
What condition is seen as a ring in the vitreous (examiner)?
Posterior vitreous detachment
275
Is posterior retinal detachment occurs with age?
It occurs with age
276
What condition is associated with posterior retinal detachment?
Posterior vitreous detachment
277
What structure is thin, semitransparent, multilayer sheet of neural tissue lining the vitreous cavity?
Retina
278
Retina ends at what structure?
Ora Serrata
279
Retina is located how many millimeters behind the Schwalbe's line temporally and nasally?
6. 5 mm behind the Schwalbe's line temporally
| 5. 7 mm nasally
280
What is the thickness of the retina at the Ora and Posterior pole?
0. 1 mm thick at the Ora
| 0. 23 mm thick at the posterior pole
281
Retina is closely attached to what structure?
RPE
282
Retina is related to what 3 structures?
Bruch's membrane
Choroid
Sclera
283
Retina is firmly attached at what 2 structures?
Optic disc
| Ora serrata
284
What are the 10 layers of the retina?
```
Internal limiting membrane
Nerve fiber layer
Ganglion cell layer
Inner plexiform layer
Inner nuclear layer
Outer plexiform layer
Outer nuclear layer of photoreceptor nuclei
External limiting membrane
Layers of rods and cones
Retinal pigment epithelium
```
285
What layer of the retina abuts the vitreous?
Internal limiting membrane
286
What layer of the retina has axons of the ganglion cells?
Nerve fiber layer
287
What layer of the retina that has axons of the bipolar and amacrine cells and dendrites of the ganglion cells and their synapses?
Inner plexiform layer
288
What layer of the retina that has nuclei of bipolar, horizontal, Mueller and amacrine cells?
Inner nuclear layer
289
What layer of the retina that is made up of the connections between photoreceptor synaptic bodies and the horizontal and bipolar cells?
Outer plexiform layer
290
What layer of the retina that is thicker at the macula (layer of Henle)?
Outer plexiform layer
291
What does the outer nuclear layer of photoreceptor nuclei contain?
Rods and cones
292
What are the 8 functions of the retinal pigment epithelium?
```
Vitamin A metabolism
Maintenance of the outer blood-retinal barrier
Phagocytosis of the photoreceptor outer segments
Absorption of light
Heat exchange
Formation of the basal lamina
Production of mucopolysaccharides
Active transport
```
293
Describe the adjacent RPE cells in the retinal pigment epithelium
Attached to each other by junctional complexes which provide both structural and metabolic stability (outer retinal barrier)
-zonula occludentes and zonula adherentes
294
What structure is retinal pigment epithelium thickest and thinnest?
Thickest at the Papillomacular Bundle
| Thinnest at the Fovea
295
What is the area of the retina that is responsible for fine, central vision?
Macula
296
What is the oval depression in the center of the macula?
Fovea
297
Fovea is approximately how many diameters away from the optic disc?
2 disc diameter
298
Fovea is slightly inferior to what structure?
Optic disc
299
What reflex is the light reflection at fovea seen during ophthalmoscopy?
Foveal reflex
300
Where is the macula located?
Area of the temporal vascular arcade
301
What structure is where more than one layer of ganglion cell nuclei can be found?
Macula
302
What is the thinnest outer nuclear layer?
Fovea
303
How many millimeters in diameter is the fovea?
1.5 mm
304
What pigment contains by the fovea?
Xanthophyll pigment
305
What is the central depression within the fovea?
Foveola
306
What 3 cells are present in foveola?
Photoreceptor cells (made up of cones)
Glial cells
Mueller cells
307
What structure is responsible for the most acute vision?
Foveola
308
What is known to be capillary-free zone?
Foveal Avascular Zone
309
What is the important landmark for treatment of subretinal neovascular membrane?
Foveal Avascular Zone
310
What nerve is not really a peripheral nerve and is actually a direct extension of the CNS?
Optic nerve
311
What is the measurement of the optic nerve horizontally and vertically?
1. 88 mm vertically
| 1. 77 mm horizontally
312
What nerve corresponds to the "blind spot" perimetry?
Optic nerve
313
How many axons do the optic nerve has?
1.2 million axons
314
How long is the optic nerve?
50 mm long
315
What are the 3 blood supply of the Circle of zinn-haller?
Short PCA
Choroidal circulation
Pial vasculature
316
What are the 4 parts of the optic nerve?
Intra-ocular (optic nerve head)
Intra-orbital
Intra-osseous/intra-cannalicular
Intra-cranial
317
What part of the optic nerve that is/has:
- 1 mm long; 1.5 mm horizontally; 1.8 mm vertically
- optic disc (visible by fundoscopy)
- non-myelinated axons
Intra-ocular
318
What part of the optic nerve that is/has:
- 25 mm in length: 3-4.5 mm in diameter
- lined by dura, arachnoid and pia mater
- fuses at the apex of the orbit with periosteum and annulus of Zinn
Intra-orbital
319
What part of the optic nerve that is/has:
- 9 mm in length
- bordered by the paranasal sinuses
- firmly anchored to the bone
Intra-osseous/intra-canalicular
320
What is the significance of firm anchorage of the intra-osseous/intra-canalicular to the bone?
A small mass lesion in the canal can cause compressive optic neuropathy even before it becomes radiological visible
321
What part of the optic nerve that is/has:
- 10 mm long, may vary from 3-16 mm
- region where the carotid artery bifurcates into ACA and MCA
Intra-cranial
322
What part of the optic nerve where the carotid artery bifurcates into ACA and MCA?
Intra-cranial
323
What is the portion of the optic nerve visible within the eye?
Optic disc
324
What structure is composed of axons whose cell bodies are located in the ganglion cell layer of the retina?
Optic disc
