Ch. 2 - Anatomy And Physiology Of The Eye And Visual System

Front 1

ocular anatomy

Back 1

the study of the structures that constitute the eye and, for completeness, usually includes the study of related structures of the brain that make up the visual pathway

Front 2

physiology

Back 2

the study of the function of the structures

Front 3

What are the 6 anatomical directions?

Back 3

superior
inferior
lateral
medial
anterior
posterior

Front 4

The orbit is, and contains:

Back 4

-the bony socket, a round opening in the skull
-it contains the eyeball and most of its accessory muscles, glands, nerves, and blood vessels

Front 5

What are the 7 orbital bones?

Back 5

frontal
maxilla
ethmoid
sphenoid
zygomatic
lacrimal
palatine

Front 6

sutures

Back 6

lines where the orbital bones are fused together

Front 7

foramens

Back 7

eight different openings allowing arteries, veins, and nerves that serve the orbital contents and parts of the face to enter and leave the orbit

Front 8

Specifically, each orbit contains...

Back 8

the eyeball, orbital fat, fascia, levator muscle & Mueller's muscle of the upper lids, lacrimal gland, optic nerve, EOMs, nerves, and circulatory supply for the orbital contents

Front 9

fascia

Back 9

connective tissue sheaths

Front 10

Which 3 orbital bones form the orbital rim at the front?

Back 10

maxilla
frontal
zygomatic

Front 11

Which orbital bone forms the apex at the back?

Back 11

sphenoid

Front 12

Which orbital bone is the thinnest?

Back 12

ethmoid - located on the medial side of the orbit and may be penetrated by infections

Front 13

sinusitis

Back 13

produces eye pain, especially when the eye moves

Front 14

Where are the thickest bones located?

Back 14

at the lateral wall of the orbit

Front 15

diplopia

Back 15

double vision - can be caused by injury or disease to the orbital bones resulting in the eye becoming displaced relative to the other eye

Front 16

sinuses

Back 16

air spaces within the bones

*named specifically for the cones that contain them: frontal, maxilla, ethmoid, & sphenoid sinuses*

Front 17

The superior wall/roof of the orbit consists of:

Back 17

the sphenoid (2%)
the frontal bone (98%)

Front 18

The medial wall of the the orbit consists of:

Back 18

(from front to back)
frontal process of the maxillary bone
lacrimal bone
ethmoid bone
a small part of the sphenoid bone

Front 19

ethmoiditis

Back 19

infection of the ethmoid sinuses - major cause of infections of the orbit and orbital contents

Front 20

lacrimal fossa

Back 20

2 depressions in the orbit, one in the medial wall contains the lacrimal sac allowing drainage of the tears from eye to nose

Front 21

The floor of the orbit consists of:

Back 21

(front to back)
maxilla
zygomatic
a small portion of the palatine
*the floor is .5-1 mm thick*

Front 22

"blowout fracture"

Back 22

blunt trauma resulting in a fracture of the orbital floor

Front 23

Laterally, the orbit is made of:

Back 23

-the zygomatic bone and the greater wing of the sphenoid bone
-is the thickest wall

Front 24

Which is the only wall not associated with paranasal sinuses?

Back 24

the lateral wall

Front 25

palpebrae

Back 25

eyelids - folds of skin that protect and reinforce the eyes and orbits

Front 26

The eyelids serve what 3 basic functions?

Back 26

-protects from small foreign bodies and light
-replenish/spread tear film across front surface
-pumps tears through lacrimal sac (regulating amount of tear fluid

Front 27

What two muscle groups control blinking?

Back 27

orbicularis
levator

Front 28

reflex blinking

Back 28

rapid forceful closure of the eyes

Front 29

blepharospasm

Back 29

condition in which the eyes are so tightly closed they cannot be opened

Front 30

palpebral aperture/fissure

Back 30

the space between the eye lids
measures ~10mm at the widest point

Front 31

ptosis

Back 31

when the palpebral aperture is too small (i.e. drooping lids) blocking the pupil

Front 32

exophthalmos

Back 32

when the palpebral aperture is too large from retracted eyelids

~> often found in patients with Grave's disease

Front 33

canthi

Back 33

the point at which the upper and lower lids meet

Front 34

lateral canthus

Back 34

the canthus closer to the ear

Front 35

medial canthus

Back 35

the canthus closer to the nose

Front 36

What are the two fleshy mounds located in the medial canthus area?

Back 36

the plica semiluminaris (the deeper of the two) and the caruncle (contains sweat and oil glands and sometimes hair)

Front 37

entropion

Back 37

eyelashes directed toward the eye by the lids turning inward (resulting from traums, scarring 2ndary to inflammation, or a loss of elasticity of the lid tissues

Front 38

ectropion

Back 38

when eyelid tissues lose their elacticity they may droop away from the eye; tears can't drain effectively; patient may report "crying" as a symptom

Front 39

gray line

Back 39

the junction of the skin and the conjunctiva

Front 40

How many layers are the eyelids constructed of?

Back 40

7
skin
subcutaneous areolar layer
orbicularis oculi
submuscular areolar layer
levator palpebrae superioris
tarsal plate
conjunctiva

Front 41

subcutaneous areolar layer

Back 41

-normally contains no fat
loosely connected over lid
-2nd layer of the eye lid

Front 42

orbicularis oculi

Back 42

-occupies entire length of the eyelid
-responsible for eyelid closure
-controlled by the facial nerve (CN VII)

Front 43

submuscular areolar layer

Back 43

-a layer of connective tissue
-similar to subcutaneous layer
-contains most of the major nervous and circulatory supplies for the lids
-fourth layer of the eyelid

Front 44

levator palpebrae superioris

Back 44

-another muscle under the areolar tissue
-extends from its origin @ the back of the orbit on the sphenoid to its insertions in the lid
-is the major muscle responsible for lid retraction
-fifth layer of the eyelid

Front 45

tarsal plate

Back 45

-is smaller in the lower lid than the upper lid (about half the size)
-comprised of dense fibrous and elastic connective tissue
-responsible for shape/rigidity of the eyelids
-sixth layer of the eyelid

Front 46

meibomia/tarsal glands

Back 46

large, parallel sebaceous glands, in the tarsal plates, running down the length of the tarsal plates
produce the oil that floats on the watery layer of the tear film to impede evaporation of the tears & prevent tear overflow

Front 47

chalazion

Back 47

-lipogranuloma of the gland
-result of a blocked meibomian gland
-internal hordeolum (an infection/inflammation of the gland)

Front 48

Mueller's muscle

Back 48

-a muscle lying below the orbital septum
-origin from levator in the upper lid & an extension of the inferior rectus muscle in the lower lid
-accounts for only 2 mm of lid elevation

Front 49

conjunctiva

Back 49

-the deepest layer of the palpebrae
-the mucous membrane that covers the inside of the lids and the outside of the globe

Front 50

marginal conjunctiva

Back 50

where the conjunctiva begins at the gray line

Front 51

tarsal conjunctiva

Back 51

the part of the conjunctiva lining the inside of the lid and tarsal plates

Front 52

orbital conjunctiva

Back 52

the part of the conjunctiva above (or below in the lower lid) the tarsal plates

Front 53

palpebral conjunctiva

Back 53

the marginal , tarsal and orbital portions of the conjunctiva covering the inside of the lids

Front 54

bulbar conjunctiva

Back 54

the conjunctiva covering the eyeball

Front 55

chemosis

Back 55

the edema of the conjunctiva

Front 56

conjunctivitis

Back 56

inflammation of the conjunctiva because of blood vessels becoming engorged because of irritation or infections

Front 57

goblet cells

Back 57

produce mucous that covers the entire surface of the conjunctiva and cornea (located in the epithelium of the conjunctiva)

Front 58

glands of Krause and Wolfring

Back 58

accessory glands that produce the watery layer of the tear film in conjunction with the lacrimal gland

Front 59

glands of Zeis

Back 59

are attached to the follicles of the eyelashes producing oil that protects the hair from drying out

Front 60

glands of Moll

Back 60

sweat glands located at the lid margin

Front 61

blepharitis

Back 61

hair shafts become infected causing lid margin to become inflamed

Front 62

blepharoconjunctivitis

Back 62

in the conjunctiva and lid margin both become infected/inflamed

Front 63

lacrimal system

Back 63

responsible for production, maintenance, and removal of the tear film

Front 64

The tear film is comprised of how many layers?

Back 64

-3
--the superficial oily layer
--the middle tear fluid/watery layer
--the mucin/mucous layer

Front 65

What does the tear layer do?

Back 65

it brings oxygen, nutrition, and natural anti-infective chemicals to the anterior surfaces of the eyeball

Front 66

epiphora

Back 66

tears spilling onto the cheek; can result from the overproduction of tears with the drainage system being normal, or normal tear production with problems draining

Front 67

the globe

Back 67

-is the eyeball itself and is essentially 3 concentric spheres: fibrous tunic, vascular tunic, and nervous tunic
-divided into anterior/posterior by the iris

Front 68

fibrous tunic

Back 68

-comprised of the cornea and the sclera
--cornea = anterior 1/6
--sclera = posterior 5/6

Front 69

vascular tunic

Back 69

-a.k.a. the uvea
-is the middle layer of the globe
-consists of the iris, ciliary body, and the choroid

Front 70

nervous tunic

Back 70

-innermost layer of the globe
-consists of the retina and retinal pigment epithelium (RPE)

Front 71

cornea

Back 71

-the major refracting surface of the eye
-unique because it's transparent
-thinner in the center vs. the edges
-has 5 layers and normally has no blood vessels
--epithelium, Bowman's, stroma, Descemet's, and endothelium

Front 72

corneal neovascularization

Back 72

when a condition exists that doesn't allow adequate circulatory support for the cornea (i.e. edema, inflammation, or inadequate tear film oxygen content), new vessels will grow into the cornea which disturs its transparency

Front 73

What covers the front surface of the cornea?

Back 73

epithelial cells

Front 74

epithelium

Back 74

-first layer of the cornea
-cells that prevent water from entering the front of the cornea and provide several layers of protection from abrasion from foreign matters

Front 75

Bowman's membrane

Back 75

-second layer of the cornea
-once this layer is damaged, the risk for scar tissue development increases drastically

Front 76

stroma

Back 76

-third layer of the cornea
-the largest layer of the cornea
-comprised of collagen

Front 77

collagen

Back 77

a specific type of connective tissue that is very tough and doesn't stretch

Front 78

Descemet's membrane

Back 78

-fourth layer of the cornea
-very thin
-doesn't have the capacity to regenerate if damaged
-if damaged may decrease transparency
-involved in maintaining the integrity of the corneal endothelium

Front 79

endothelium

Back 79

-fifth layer of the cornea
-a single-thickness layer of cells consisting of about 500,000 cells @ birth that don't regenerate
-transports nutrients from the aqueous humor to the cornea

Front 80

keratoconus

Back 80

the stroma of the cornea is thinned and the IOP causes the cornea to bulge forward

Front 81

sclera

Back 81

-makes up the posterior 5/6 of the fibrous tunic along with the episcleral connective tissue
-made of collagen fibers

Front 82

episclera

Back 82

is a layer of connective tissue lying between the sclera and the bulbar conunctiva

Front 83

choroid

Back 83

-the layer just interior to the sclera and it provides some of the vascular support
-represents the majority of the vascular tunic
-a network of blood vessels that provides vascular support

Front 84

What are the 3 parts of the vascular tunic?

Back 84

the choroid, the ciliary body, and the iris

Front 85

trabecular meshwork

Back 85

-located at the junction of the uvea
-acts as a drain for the intraocular fluid that is continually produced in the eye

Front 86

How does the iris get its color?

Back 86

from the amount of melanin/pigment it contains

Front 87

iris

Back 87

-divides the eye's internal space into the anterior chamber (infront of the iris) and the posterior chamber (behind the iris)
-the "colored part" of the eye

Front 88

What are the 3 layers of the iris?

Back 88

1) the stroma - made of loosely structured collagen fibers
2) the non-pigmented epithelium
3) the pigmented epithelium

Front 89

The stroma layer of the iris contains:

Back 89

the melanocytes/pigment cells, the sphincter/constrictor muscle, and the blood vessels

Front 90

sphincter muscle

Back 90

-a.k.a. the constrictor muscle
-makes the pupil get smaller in bright light

Front 91

non-pigmented epithelium

Back 91

is basically the dilator muscle, which is responsible for opening the pupil in the dark

Front 92

How are the 2 muscles in the eye controlled?

Back 92

-non-voluntary
-part of the autonomic (non-voluntary) nervous system

Front 93

mydriatic drugs

Back 93

make the pupil larger by stimulating the dilator muscle

*acts as the sympathetic nerves to*

Front 94

cycloplegic drugs

Back 94

makes the pupil larger by paralyzing the sphincter muscle

*"knocks out" the parasympathetic system*

Front 95

posterior synechia

Back 95

when the iris sticks to the lens as a result of inflammation to the iris

Front 96

pigmented epithelium

Back 96

-the deepest layer of the iris
-very darkly pigmented, extending around the edge of the pupil (pupillary frill)

Front 97

Where is the ciliary body located?

Back 97

immediately behind the iris and just inside the sclera

Front 98

What are the layers of the ciliary body?

Back 98

the ciliary muscle (makes up the bulk of the ciliary body) and the stroma (contains the blood vessels and ciliary processes)

Front 99

ciliary processes

Back 99

responsible for the production of aqueous humor

Front 100

How does the aqueous humor flow in the eye?

Back 100

enters posterior chamber in front of the lens, flows through the pupil into the anterior chamber where it comes into contact with and filters through the trabecular meshwork to the canal of Schlemm, then empties into the aqueous veins of Ascher in the sclera and mixed with blood, then removed from the eye

Front 101

aqueous humor

Back 101

-fills front part of the posterior chamber between the lens and the iris, and the entire anterior chamber
-provides nutrients for the lens and posterior cornea and carries away waste products, and maintains IOP since it's the only fluid continually produced in the eye

Front 102

ocular hyptertension

Back 102

if the rate of IOP production is too high or the rate of drainage is too low, pressure increases

Front 103

ocular hypotension

Back 103

usually due to penetrating injury, but can result as a decrease in aqueous production because of inflammation in the ciliary body

Front 104

What are the functions of the ciliary body?

Back 104

-produces aqueous humor
-accommodation
-secretion of one component of vitreous humor
-prevents passage of material into the aqueous humor
-helps control the flow of the aqueous humor into the trabecular meshwork

Front 105

presbyopia

Back 105

lack of focusing ability usually caused as the eye loses its elasticity with age

Front 106

ophthalmic artery

Back 106

-all of the blood supply to the eye comes through this artery
-bloody supply fills the choroid through 2 sets of smaller vessels

Front 107

central retinal artery

Back 107

is the ophthalmic artery (just renamed) after the long and short ciliary arteries have branched off into the eye

Front 108

Haller's layer

Back 108

outermost layer of the choroid, made up of larger vessels

Front 109

Sattler's layer

Back 109

2nd layer of the choroid, vessels are considered to be medium sized

Front 110

How are the vessels of Haller's and Sattler's layers classified?

Back 110

arterioles and venules, because of the construction of their walls

Front 111

choriocapillaris

Back 111

3rd layer of the choroid, vessels are primarily capillaries

Front 112

Bruch's membrane

Back 112

thin layer of connective tissue separating the choriocapillaris and the retina - most internal layer of the choroid

Front 113

What is the retina's general function?

Back 113

to convert the light energy falling onto it into electrical impulses that can be analyzed by the brain

Front 114

What are the 10 layers of the retina?

Back 114

"In New Generation It Is Only Ophthalmologists Examine Patient's Retina" (inner to outer)
10)inner limiting membrane 9)nerve fiber layer 8)ganglion cell 7)inner plexiform 6)inner nucleus 5)outer plexiform 4)outer nuclear 3)external limiting membrane 2)photoreceptors 1)RPE

Front 115

retinal pigment epithelium (RPE)

Back 115

most external retinal layer
provides vitamin A to the photoreceptors
transports nutrients into the retina
phagocytize ("eat") the used-up portions of the photoreceptor cells
prevents the intraocular reflection of stray light

Front 116

photopigments

Back 116

the chemicals that are used to collect the light energy in the photoreceptors

Front 117

retinitis pigmentosa

Back 117

a genetic defect that results in the RPEs not "eating" up the used portions of the photoreceptor cells; starts as night blindness; can progress to total blindness

Front 118

axon

Back 118

one end of a nerve cell

~> specialized for transmitting neural impulses

Front 119

dendrite

Back 119

one end of a nerve cell

~> specialized to receive neural impulses

Front 120

synapse

Back 120

a small gap located between the axon of one cell and the dendrite of the next

Front 121

neurotransmitter

Back 121

the chemical released from the axon that floats across the synapse and stimulates the dendrite of the next nerve cell in line

Front 122

photoreceptor layer

Back 122

2nd layer of the retina

2 types of photoreceptors: rods and cones

Front 123

How do rods and cones differ?

Back 123

anatomically, in their physiologic response characteristics, and in their distribution throughout the retina

Front 124

cones

Back 124

-have pointed (cone shaped) outer segments called receptors
-responsible for color discrimination
-require much higher light levels to be stimulated than rods

Front 125

rods

Back 125

-have flat outer segments called receptors
-response of the rods is based on the presence/absence of light energy

Front 126

Conditions of color deficiency are predominantly:

Back 126

errors of the cones

Front 127

Problems seeing in dim illumination are usually because of:

Back 127

rod dysfunctions

Front 128

macula lutea/macula

Back 128

-central 1 cm of the retina
-called the macula because it has a pigment that gives it a yellow color
-photorecedptors (mainly cones) are the most dense in this area

Front 129

fovea

Back 129

a depressed area in the center 1.5 mm of the macula

Front 130

foveola

Back 130

-the area in the fovea that contains ONLY cones
-responsible for fine discriminations and high VA

Front 131

external limiting membrane

Back 131

-3rd layer of the retina
-not really a membrane; it's the point at which the photoreceptors are joined together by a specific type of cellular junction called zonula adherens
-marks the midpoint of the length of rods and cones

Front 132

outer nuclear layer

Back 132

-4th layer of the retina
-where the cell bodies of the photoreceptors are located
-these cell bodies contain the nuclei

Front 133

outer plexiform layer

Back 133

-5th layer in the retina
-contains the first synapses in the visual pathway in this layer
-the last layer to be supported by the choroidal circulation

Front 134

plexiform

Back 134

the term given to layers without cell bodies that contain synaptic sites

Front 135

bipolar cells

Back 135

-provide for the transmission of the visual signal, up the visual pathway, toward the brain
-acts as a 'relay' or 'wire'
-this is called a "vertical" transmission

Front 136

horizontal cells

Back 136

-connect receptors to other receptors and horizontal cells
-these connections are involved in integrating the input from groups of cells into receptive fields
-represent horizontal processing of visual information

Front 137

Which cell bodies are found in the 6th layer of the retina?

Back 137

-the cell bodies of bipolar and horizontal cells, Mueller's cells, and amacrine cells
-6th retinal layer=inner nuclear layer

Front 138

Muller cells

Back 138

are nutritional support cells that are scattered throughout all layers internal to the outer nuclear layer, specifically layers 5-9

Front 139

inner nuclear layer

Back 139

-6th layer of the retina
-is the first (most external) layer that is completely supported by the circulation of the retina

Front 140

amacrine cells

Back 140

have no apparent axons or dendrites, they have processes that allow bi-directional transmission of neural signals ("horizontal" processing)

Front 141

inner plexiform layer

Back 141

-7th layer of the retina
-where the amacrine cells' processes and the axons of the bipolar cells connect to the ganglion cells

Front 142

ganglion cells

Back 142

-another step in the transmission of visual impulses to the brain
-visual information is carried via the axons of the ganglion cells out of the eye ("vertical" processing)

Front 143

ganglion cell layer

Back 143

-8th layer of the retina
-consists of the cell bodies of the ganglion cells

Front 144

optic nerve (CN II)

Back 144

the axons of ganglion cells collect as a bundle to create the optic nerve (CN II)

Front 145

nerve fiber layer

Back 145

-9th layer of the retina
-on their way to form the optic nerve (CN II), the axons of the ganglion cells run across the inside of the retina which constitutes this 9th layer

Front 146

internal limiting membrane

Back 146

-10th layer of the retina
-separates the ganglion cell layer from the face of the vitreous
-comprised of collagen fibers that connect the Mueller cells

Front 147

cortex

Back 147

the elongated cells/fibers in the lens are collectively called the cortex

Front 148

Because of what process allows the lens to grow throughout life?

Back 148

-a single layer of epithelium
-some cells of which elongate to form new cortical fibers, surrounds the cortex, thus allowing continuous growth

Front 149

capsule

Back 149

is a tough elastic membrane that surrounds the lens

Front 150

zonular fibers

Back 150

-a.k.a. zonules
-is what the lens is suspended by from its edge to the ciliary muscle

Front 151

lens

Back 151

-is a structure comprised mostly of elongated epithelial cells that are arranged in concentric layers (like an onion)
-is the 2nd most powerful refracting/light focusing component of the eye

Front 152

What is the simplified explanation of the process by which people focus their eyes?

Back 152

the ciliary muscle tightens, allowing the zonules to loosen, and the elasticity of the capsule makes the lens bulge in the center so that it becomes thicker and more powerful

Front 153

vacuole

Back 153

-a space between the lens fibers
-can be caused by mechanical swelling of the lens, damage from radiation, or a metabolic disturbance

Front 154

Vacuoles usually lead to what?

Back 154

a clouding of the lens (cataracts)

Front 155

How are cataracts named?

Back 155

location, cause, size, density, or time of occurence

Front 156

The first part of the visual pathway involves:

Back 156

the structures from the rods and cones to the optic nerve

Front 157

The second part of the visual pathway involves:

Back 157

from the eye, specifically, the optic nerve, to the visual cortex

Front 158

The visual pathway runs:

Back 158

a horizontal path from the front of the head to the back of the head

Front 159

visual cortex

Back 159

is the part of the brain responsible for analyzing the neural signals representing sight

Front 160

visual field

Back 160

the expanse of vision that a person sees

Front 161

perimetry

Back 161

-visual field testing
-measures the visual field in each eye
-can help determine where in the visual pathway a disease exists

Front 162

How are the "sectors" of the retina created?

Back 162

-quadrants
-by dividing the retina into halves with imaginary lines vertically and horizontally through the fovea

Front 163

optic chiasm

Back 163

is formed by the fusion of the optic nerves inside the skull near the pituitary gland

Front 164

left optic tract

Back 164

-consists of a bundle of fibers including TEMPORAL retinal fibers from the LEFT eye and NASAL retinal fibers from the RIGHT eye
-they continue from the left side of the chiasm
-represents the RIGHT side of the visual field

Front 165

right optic tract

Back 165

-consists of a bundle of fibers including TEMPORAL retinal fibers from the RIGHT eye and NASAL retinal fibers from the LEFT eye
-they continue from the right side of the chiasm
-represents the LEFT side of the visual field

Front 166

scotomas

Back 166

loss of sensitivity/visual sensation in part of the field of both eyes

Front 167

quadrantanopsia/quadrantanopia

Back 167

a field defect that affects about 1/4 of the VF

Front 168

hemianopsia/hemianopia

Back 168

a field defect that affects about 1/2 of the VF

Front 169

homonymous

Back 169

when a field defect exists in both eyes and affects the same field in both eyes

Front 170

prechiasmal lesions

Back 170

lesions involving the retina or the optic nerve, which results in a unilateral (one eye) field defect

Front 171

chiasmal/postchiasmal lesions

Back 171

lesions involving the retina or the optic nerve resulting in a bilateral (often homonymous) field defects

Front 172

binasal hemianopsia

Back 172

-field defect resulting from damage to the temporal fibers
-NOT homonymous

Front 173

bitemporal hemianopsia

Back 173

-field defect resulting from damage to the nasal fibers
-NOT homonymous

Front 174

lateral geniculate nucleus (LGN)

Back 174

-where the optic tract ends
-a pyramid shaped mass of cells where a synapse occurs between the terminal ends of the ganglion cell axons and the dendrites of the nerve fibers, which carry the visual information to the visual cortex

Front 175

congruous

Back 175

identical

Front 176

optic raditations

Back 176

the axons of the cells of the LGN continue to the visual cortex

Front 177

Brodmann's area 17

Back 177

-located at the very back tip of the brain
-the part of the occipital cortex that receives the fibers of the optic radiation from the LGN and is the primary receptive area for vision

Front 178

macular sparing

Back 178

-an unusual feature of he congruous homonymous hemianopsia
-the term given to a VF when a complete hemianopsia exists except for the central 2-5 degrees where the field is intact

Front 179

association fibers

Back 179

distribute the visual information to the cortex for analysis and for association with other sensory data and motor coordination

Front 180

Brodmann's area 8

Back 180

-responsible for planning eye movements
-located in the frontal lobe
-one of the major pathways of the association is from the visual cortex to this area

Front 181

How are the extraocular muscles unique from others in the body?

Back 181

the number of muscle fibers controlled by each nerve fiber is very small, allowing very accurate control of eye movements

Front 182

striated muscles

Back 182

voluntarily controlled

Front 183

common tendinous ring/annulus of Zinn

Back 183

-the common tendon from which arise the four recti muscles of the eye
-it surrounds the optic foramen and a part of the medial end of the superior orbital fissure

Front 184

medial rectus

Back 184

-most powerful of the EOMs
-runs from its origin at the optic foramen, along the medial wall, to its insertion onto the sclera
-has only one action adduction
-controlled by the inferior branch of the oculomotor (CN III)

Front 185

adduction

Back 185

turns the eye inward toward the nose

Front 186

inferior rectus

Back 186

-runs along the floor from the orbital apex to its insertion
-makes a 23 degree angle with the medial wall
-primary action is depression; also adducts and extorts slightly
-controlled by the inferior division of the oculomotor nerve (CN III)

Front 187

depression

Back 187

turns the eye downward

Front 188

extorsion

Back 188

turns top of eye out toward the temple and the bottom of eye in toward the nose

Front 189

lateral rectus

Back 189

-runs along the lateral wall
-has only one action abduction
-controlled by the abducens nerve (CN VI)

Front 190

abduction

Back 190

moves eye away from the midline, toward the temple

Front 191

superior rectus

Back 191

-makes a 23 degree angle with the medial wall
-primary action is elevation; also abducts and slightly helps with intorsion
-controlled by a branch of the oculomotor nerve (CN III)

Front 192

elevation

Back 192

turns eye upward

Front 193

intorsion

Back 193

turns bottom of eye toward nose and bottom toward the temple

Front 194

superior oblique

Back 194

-originates on or very near the annulus of Zinn on the sphenoid bone and runs along the superior wall to a small bony loop at the front of the orbit called the trochlea
-makes a 51-53 degree angle with the medial wall
-primary action is depression, abduction, and intorsion

Front 195

inferior oblique

Back 195

-the only EOM that originates at the front of the orbit, beginning at a fossa in the maxillary bone and runs between the eye and the inferior rectus
-primary action is elevation and abduction, and extorsion
-controlled by a division of the oculomotor nerve (CN III)

Front 196

antagonist

Back 196

something, such as a muscle, disease, or physiological process, that neutralizes or impedes the action or effect of another

Front 197

agonist

Back 197

a contracting muscle that is resisted or counteracted by an antagonist muscle

Front 198

strabismus

Back 198

-"squint"
-the condition present when both eyes cannot be directed to an object of regard at the same time
-"lazy eye"

Front 199

heterophoria

Back 199

the condition in which there is a tendency for the eyes to misalign, but the person can overcome that tendency so that both eyes do point at objects of regard

Front 200

ductions

Back 200

eye movements tested monocularly

Front 201

versions

Back 201

binocular eye movements in the same direction

Front 202

vergence testing

Back 202

testing with the eyes moving in opposite directions

Front 203

What are the 3 types of vergences?

Back 203

convergence
divergence
vertical divergence

Front 204

convergence

Back 204

both eyes turn toward the nose

Front 205

divergence

Back 205

both eyes turn away from the nose

Front 206

vertical divergence

Back 206

one up turns up the other turns down

Front 207

antagonist muscle pairs in one eye

Back 207

muscle antagonist
medial rectus lateral rectus
lateral rectus medial rectus
superior rectus inferior rectus
inferior rectus superior rectus
superior oblique inferior oblique
inferior oblique superior oblique

Front 208

agonist muscle pairs in two eyes

Back 208

right eye left eye
medial rectus lateral rectus
lateral rectus medial rectus
superior rectus inferior oblique
inferior rectus superior oblique
superior oblique inferior rectus
inferior oblique superior rectus

Front 209

The thinnest bone of the orbit is:

Back 209

ethmoid

Front 210

The floor of the orbit is composed of which three bones?

Back 210

maxilla
zygomatic
palatine

Front 211

The condition in which the eyes are so tightly closed they can't be opened is called:

Back 211

blepharospasm

Front 212

When the eyelid turns in toward the globe, the condition is called:

Back 212

entropion

Front 213

Which muscle is responsible for eyelid closure and is controlled by the facial nerve (CN VI)?

Back 213

obicularis oculi

Front 214

When a meibomian gland becomes blocked and a red, painful bump appears on the lid, it is called:

Back 214

chalazion

Front 215

Any interruption in the innervation to Mueller's muscle results in:

Back 215

ptosis

Front 216

The bulbar conjunctiva covers what?

Back 216

the eyeball

Front 217

The __________ system is responsible for the production, maintenance, and elimination of the tear film.

Back 217

lacrimal

Front 218

Tears spilling onto the cheek is called:

Back 218

epiphoria

Front 219

The anterior chamber and posterior chamber in front of the lens are filled with :

Back 219

aqueous

Front 220

The vascular tunic/uvea consists of (from front to back):

Back 220

iris
ciliary body
choroid

Front 221

The innervation of the cornea is mainly sensory branches of what nerve?

Back 221

cranial nerve V (trigeminal)

Front 222

What condition is the most common cause of red eyes?

Back 222

conjunctivitis

Front 223

What is one of the major functions of the ciliary body?

Back 223

accommodation

Front 224

The bloody supply to the eye comes through what?

Back 224

ophthalmic artery

Front 225

The ______________ is the area of the retina that is responsible for fine discriminations and high VA.

Back 225

fovea

Front 226

Which structure is the second most powerful refracting component of the eye?

Back 226

the lens

Front 227

In the visual pathway, if a lesion occurs at the chiasm, the resultant field defects are usually:

Back 227

bilateral

Front 228

Which of the rectus muscles in innervated by cranial nerve VI

Back 228

lateral

Front 229

Which rectus muscle's primary action is depression?

Back 229

inferior

Front 230

Which rectus muscle is the strongest and is responsible for adduction of the eye?

Back 230

medial

Front 231

The tertiary action of the superior oblique is:

Back 231

intorsion

Front 232

Extorsion is described as rotating the top of the eyeball ______ and the bottom ______.

Back 232

out, in

Front 233

Which EOMs are involved when the patient's gaze is far left and up?

Back 233

left superior rectus and right inferior oblique