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Ocular Anatomy > Orbit Overview > Flashcards

Orbit Overview Flashcards

1
Q

What does the orbit socket contain?

A

the globe, connective tissue,
extraocular muscles (EOMS),
orbital nerves, blood vessels,
and fat

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2
Q

What three coats (tunics) does the globe
consist of?

A

Outer fibrous layer (cornea &
sclera), middle vascular layer
(iris, ciliary body, choroid), and
inner neural layer (retina)

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3
Q

What three chambers are filled with fluid in
the globe?

A

Anterior, posterior, and vitreous

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4
Q

What is the sheet of dense connective tissue
that covers the sclera?

A

Tenon’s capsule (Bulbar fascia)

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5
Q

Describe the attachment of Tenon’s capsule

A

Anteriorly merges with sclera/
conjunctiva at the limbus.
Posteriorly is continuous with
the dural sheath of the optic
nerve.

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6
Q

What is the purpose of Tenon’s capsule?

A

-provides a strong barrier
-separates the globe from
contents of orbit
-prevents orbital infections
from entering the globe

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7
Q

What is the transition between the cornea
and tenon’s capsule/sclera referred to?

A

Limbus

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8
Q

Why is Tenon’s capsule continuous with
dura sheath posteriorly?

A

The optic nerve must pierce
sclera and tenon’s capsule to enter the globe

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9
Q

Sheet of dense connective tissue that extends
the entire rim of the orbit to the tarsal
plate

A

Orbital septum (Palpebral fascia)

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10
Q

Describe the attachment of the orbital septum

A

Continuous with the periosteum
at the superior and inferior
orbital rim

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11
Q

What is the purpose of the orbital septum?

A

Anterior barrier of the orbit
-separates the eyelids and
lacrimal sac from the orbit and
keeps the orbital fat in place

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12
Q

What does the orbital septum prevent from
entering the orbit?

A

Facial/eyelid/nasolacrimal
system infections

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13
Q

Rim where the orbital septum originates

A

Arcus margins

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14
Q

Sheet of dense connective tissue that covers
the bones of the orbit

A

periorbital (orbital fascia, periosteum)

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15
Q

Describe the attachment of periorbita

A

anteriorly- continuous with the
periosteum of facial bones
and orbital septum
posteriorly- continuous with
dural sheath of the ON and
forms the common tendinous
ring

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16
Q

Cranial nerve II

A

optic nerve

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17
Q

cranial nerve III

A

oculomotor

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18
Q

cranial nerve IV

A

Trochlear

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19
Q

cranial nerve V and its branches

A

Trigeminal
-V1 ophthalmic
-V2 maxillary
-V3 mandibular

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20
Q

cranial nerve VI

A

abducens

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21
Q

What blood vessels are in the orbit?

A

-Ophthalmic artery and its
branches
-superior and inferior ophthalmic
vein and its branches

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22
Q

Transverse dense connective tissue located
in the superior orbit and courses from
lateral orbital wall to medial orbital wall

A

Whitnall’s ligament

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23
Q

What is the function of Whitnall’s ligament?

A

Provides support and maintains
spatial movement between
anatomic structures in
the superior orbit

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24
Q

How is the Whitnall’s Ligament formed?

A

By condensation of the levator
muscle and is the point where
the levator muscle fibers end
and the levator aponeurosis
begins

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25
Q

What is the function of levator aponeurosis?

A

moves the eyelid

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26
Q

Transverse dense connective tissue located
in the inferior orbit and courses from
lateral orbital wall to medial orbit wall

A

Lockwood’s ligament

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27
Q

What is the function of Lockwood’s Ligament?

A

-provides support and maintains
spatial relationships between
anatomic structures in
the inferior orbit
-contributes to the formation
of the capulopalpebral fascia

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28
Q

What is the function of the capulopalpebral
fascia?

A

dense connective tissue that
acts as a muscle to move the
lower eyelid

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29
Q

Transverse dense connective tissue that is
an expansion of the sheath of the medial
rectus and attaches to the lacrimal bone

A

Medial check ligament

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30
Q

What is the function of medial check ligament?

A

Prevents overaction of the medial
rectus

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31
Q

Transverse dense connective tissue that is
an expansion of the sheath of the lateral
rectus and attaches to the zygomatic bone

A

Lateral check ligament

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32
Q

What is the function of the lateral check
ligament?

A

prevents overaction of the lateral
rectus

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33
Q

Which ligaments come together to form
the supporting hammock-like structure for
the globe?

A

-Whitnall’s
-Lockwood’s
-Medial check
-Lateral check

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34
Q

Web of interconnecting connective tissue
septa that organizes the orbital space surrounding
the globe

A

Orbital septal system

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35
Q

What is the function of the orbital septal
system?

A

Anchors and supports EOMS
(muscles), nerves, and blood
vessels

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36
Q

What are the extraocular muscles?

A

-Recti muscles: medial, lateral,
superior, and inferior
-Oblique muscles: superior
and inferior

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37
Q

What muscles play a role in eyelid retraction?

A

levator palpebrae, Müller’s
muscle (Tarsal), capsulopalpebral
fascia (not actually
a muscle)

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38
Q

Space not occupied by orbital structure
and filled with adipose tissue

A

orbital fat

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39
Q

What is the purpose of orbital fat (adipose)?

A

-surrounds the ON and separates
it from the EOMs
-separates muscles in the orbit
from the orbital walls

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40
Q

In the anterosuperior orbit, what 2 pads are
anterior to the levator aponeurosis?

A

nasal, central

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41
Q

What 3 fat pads are posterior to the orbital
septum and anterior to the capsulopalpebral
fascia?

A

nasal, central, temporal

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42
Q

hole or opening in bone that allows entrance
and exit of nerve and vessels in and
out of the orbit

A

foreamen

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43
Q

long, narrow opening in bone that allows
entrance and exit of nerves and vessels in
and out of the orbit

A

fissure

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44
Q

shallow depression in bone that contains
anatomical structures

A

fossa

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45
Q

What are the foramen of the orbit?

A

optic foramen (canal), supraorbital
foramen, supratrochlear
foramen, and infraorbital
foramen

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46
Q

What are the fissures located in the orbit?

A

superior and inferior orbital fissure

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47
Q

What fossa are located in the orbit?

A

two lacrimal fossa

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48
Q

Where is the optical canal?

A

-lies between the lesser wing
and body of sphenoid
-at the orbital apex

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49
Q

What is the function optical canal?

A

opening between the orbit and
cranial cavity that allows CN II
and ophthalmic artery to pass
through

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50
Q

What is the common tendinous ring (annulus
of zinn)?

A

band of connective tissue that
lies anterior to optic canal

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51
Q

What is the function of annulus of zinn?

A

origin for the 4 EOMs (muscles)

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52
Q

If a patient has an orbital infection, why
must they be treated immediately?

A

Because the optic canal connects
the orbit and cranial cavity
so the infection can easily
spread to brain

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53
Q

Where is the superior orbital fissure?

A

-Lies between the greater and
lesser wings of the sphenoid
-inferior portion at the orbital
apex

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54
Q

What nerves pass through the superior orbital
fissure through the annulus of zinn?

A

-Superior and inferior division
of oculomotor nerve (CN III)
-nasociliary nerve (CN V1)
-abducens nerve (CN VI)

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55
Q

What nerves and vessels pass through the
superior orbital fissure and above the annulus
of zinn?

A

-superior ophthalmic vein
-trochlear nerve (CN IV)
-lacrimal nerve (CN V1)
-frontal nerve (CN V1)

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56
Q

Which cranial nerve provides sensory of
touch that results in discomfort when you
touch your superior orbit?

A

CN V -trigeminal

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57
Q

Where is the inferior orbital fissure (infraorbital
fissure)?

A

Lies between the floor of the
orbit and lateral wall

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58
Q

What nerves and vessels pass through the
inferior orbital fissure?

A

-inferior ophthalmic vein
-zygomatic nerve (CN V2)
-infraorbital nerve (CN V2),
artery, and vein

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59
Q

Where do the infraorbital nerve (CN V2),
artery, and vein go after passing through
the inferior orbital fissure?

A

Continue along the infraorbital
groove to pass through the infraorbital
canal and infraorbital
foramen

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60
Q

Where is the lacrimal fossa (for lacrimal
gland) located?

A

located in the frontal bone
temporally

61
Q

Where is the lacrimal fossa (for the
lacrimal sac) located?

A

-medially
-formed by the lacrimal bone
(posterior lacrimal crest) and
the frontal process of maxillary
bone (anterior lacrimal
crest)

62
Q

Which canal extends from the maxillary
bone from the lacrimal fossa to open into
the nasal cavity?

A

nasolacrimal canal (nasolacrimal
duct within this canal)

63
Q

Why is the lacrimal fossa (for the lacrimal
sac) not consider apart of the orbit?

A

It is considered medial to the
orbit because it is separated
by the orbital septum

64
Q

How does an infection spread when it occurs
within the lacrimal sac?

A

Can spread to nasal cavity but
not the orbit because of the
barrier protection from orbital
septum

65
Q

Where is the superior orbital (supraorbital)
foramen/ notch located?

A

Located in the frontal bone
medially

66
Q

Why can the supraorbital foramen also be
called a notch?

A

Varies among individuals,
could be a notch or hole

67
Q

What is the function of the supraorbital
foramen?

A

-opening between the orbit
and facial surface
-supratrochlear nerve (CN
V1), artery, and vein pass
through

68
Q

Where is the inferior orbital (infraorbital)
foramen located?

A

maxillary bone

69
Q

What is the function of the infraorbital foramen?

A

opening between orbit and facial
surface
-infraorbital nerve (CN V2),
artery, and vein pass through

70
Q

skeleton of head

A

skull

71
Q

What two parts make up the skull?

A

-cranium
-face

72
Q

Bones meet at _______________________,
a seam-like immovable joint

A

suture

73
Q

Exception to bones forming sutures

A

movable temporomandibular
junction (TMJ)

74
Q

Air-filled cavities within several of the skull
bones

A

sinuses

75
Q

What are the bones of the cranium?

A

frontal, parietal, temporal, occipital,
sphenoid, ethmoid

76
Q

Bone that forms the anterior portion of the
cranium, anterior floor, and superior part
of the face

A

frontal

77
Q

Bone that forms the roof of cranium and
lateral sides of skull skull

A

parietal

78
Q

Bone that forms the floor of cranium and
lateral sides of skull

A

temporal

79
Q

Bone that forms the posterior portion of
the cranium and posterior floor of cranium

A

occipital

80
Q

Where is the foramen magnum located?

A

inferior aspect of the occipital bone

81
Q

Bone that forms the floor of cranium

A

sphenoid

82
Q

What are the three portions of sphenoid
bone?

A

-body
-lesser wing
-greater wing

83
Q

What is housed in the sella turcica of the
body of sphenoid?

A

Pituitary gland

84
Q

What are the four parts of the ethmoid
bone and what are their functions?

A

-Vertical (perpendicular) plate
forms nasal septum
-horizontal (cribriform) plate
allows olfactory nerves to
pass through
-Labyrinths (2) house ethmoidal
sinuses

85
Q

What are the bones of the face?

A

frontal, palatine, lacrimal,
nasal, inferior conchae,
vomer, zygomatic bone (2),
maxillary (2), and mandible

86
Q

Bone that forms the forehead and orbital
roof

A

frontal

87
Q

Bone that extends from the hard palate at
the of the mouth to the orbital floor

A

palatine

88
Q

Bone that forms the bridge of the nose

A

nasal

89
Q

Bone that is located along the lateral wall
of nasal cavity

A

inferior conchae

90
Q

Bone that forms the posterior part of nasal
septum

A

vomer

91
Q

Bone that forms the lateral part of cheekbone
and the lateral wall and floor of orbit

A

zygomatic

92
Q

Bone that forms the upper jaw, cheek, hard
palate, lateral wall of nasal cavity, and floor
of orbit

A

maxillary

93
Q

Bone that forms the moveable lower jaw

A

mandible

94
Q

What does the orbit contain?

A

Globe, connective tissue,
EOMs, orbital nerves, blood
vessels, fat

95
Q

What is the shape of the orbit?

A

Shaped like a 4-sided pyramid
with the apex posteriorly and
the base anteriorly

96
Q

Where is the apex of the orbit located?

A

slightly nasal

97
Q

What are the dimensions of the orbit?

A

40 mm (width) x 35 mm
(height) x 45 mm (depth)
3 cc (volume)

98
Q

What bones form the orbit?

A

frontal, palatine, lacrimal, zygomatic,
maxillary, sphenoid,
ethmoid

99
Q

What bones form the orbit roof?

A

frontal bone and lesser wing
of sphenoid

100
Q

What bones form the floor of the orbit?

A

palatine, zygomatic, and maxillary
bones

101
Q

Why is the floor of the orbit the weakest
wall?

A

-infraorbital groove/canal in
maxillary bone
-maxillary sinus below floor

102
Q

What are symptoms of patient that break
floor of orbit?

A

blurred vision and lose of feeling
in cheek because CN
V2 (infraorbital nerve) goes
through infraorbital foramen in
maxillary bone

103
Q

What bones for the medially (nasal) wall of
orbit?

A

ethmoid, maxillary, lacrimal,
and body of sphenoid bones

104
Q

Why is the medial wall the thinnest wall of
the orbit?

A

Because lamina papyracea of
ethmoid bone is filled with sinuses

105
Q

What is the disadvantage of the medial
wall being the thinnest wall?

A

Ethmoid sinus infections can
spread to the orbit

106
Q

What bones make up the lateral (temporal)
wall of the orbit?

A

zygomatic and greater wing of
sphenoid bone

107
Q

Why is it important for the lateral orbital
rim to be the strongest area of the orbit?

A

Most exposed to possible injury

108
Q

What is the purpose of paranasal sinuses?

A

Reduce the weight of the skull
and filter air we breathe

109
Q

What are the four paranasal sinuses?

A

maxillary, frontal, ethmoid,
sphenoid

110
Q

Where is the maxillary sinus in regards to
the orbit?

A

inferior

111
Q

Where is the sphenoid sinus in regards to
the orbit?

A

posterior and medial

112
Q

Where is the ethmoid sinus in regard to the
orbit?

A

medial

113
Q

Where is the frontal sinus in regards to the
orbit?

A

superior

114
Q

Infection in the air cavities is called

A

sinusitis

115
Q

If a patient comes in and says that their eye
hurts due to pressure around the eye, what
does that mean?

A

infection in sinus

116
Q

Why is the eye called a globe?

A

hollow structure that encloses
cavity filled with fluid

117
Q

Components of outer fibrous layer of
globe

A

Sclera and cornea

118
Q

Characteristics of sclera

A

-85% of fibrous portion
-opaque white color

119
Q

Functions of sclera

A

-provides protection for the
structures within
-maintains the shape of globe

120
Q

Sclera is divided into:

A

sclera and episclera

121
Q

What is the sclera covered by?

A

-tenons capsule
-conjuctiva

122
Q

Characteristics of cornea

A

-15% of fibrous portion
-transparent to allow light rays to enter the eye

123
Q

What are the functions of cornea?

A

refraction occurs here, helps
to bring light rays into focus on
the retina

124
Q

Location where the cornea transitions to
sclera/Tenon’s capsule/conjuctiva

A

limbus

125
Q

Vascular layer (Uvea) is composed of

A

iris, ciliary body, and choroid

126
Q

Characteristics of iris

A

-anterior layer of the uvea
-gives eye color
-hole in the center called the
pupil

127
Q

What are the two muscles of the iris?

A

Iris dilator and iris sphincter

128
Q

iris muscle that contractions dilate the
pupil (during dimmer times so allow more
light in eye)

A

iris dilator

129
Q

iris muscle that contractions constrict the
pupil (during bright light to let less light in)

A

iris sphincter

130
Q

Middle layer of the uvea and continuous of
iris

A

ciliary body

131
Q

What does the ciliary body consist of?

A

ciliary muscle and ciliary
processes

132
Q

What is the function of the ciliary muscle?

A

Contracts and relaxes to regulate
the thickness of the lens
and allow accommodation for
near and far vision

133
Q

What at the zonules?

A

suspensory ligaments that attach
the ciliary muscle to crystalline
lens

134
Q

What is the function of ciliary processes?

A

produce and secrete aqueous
humor (clear fluid that provide
nutrients to structures of the
eye like the lens)

135
Q

Posterior layer of uvea (continuous of ciliary
body)

A

choroid

136
Q

What is the function of choroid?

A

network of blood vessels that
provide nutrition to the outer
1/3 of retina

137
Q

What does the inner neural layer consist
of?

A

retina

138
Q

What is the function of the retina?

A

Neural tissue that converts
light energy into an electrical signal that can be transmitted to the brain

139
Q

Retina creates electrical signal that exits
the eye and enters the brain via the

A

optic nerve

140
Q

Anterior portion of the optic nerve is called
the

A

optic disc or optic nerve head

141
Q

Small area at the center of the retina responsible
for central vision

A

macula

142
Q

located in the center of the macula and
provides highest visual acuity

A

fovea

143
Q

Interior of the eye is made up 3 chambers
filled with fluid:

A

anterior, posterior, and vitreous
chamber

144
Q

Where is the anterior chamber?

A

between cornea and iris

145
Q

Where is the posterior chamber located?

A

between ciliary body and lens

146
Q

The anterior and posterior chamber are
continuous of one another through the:

A

pupil

147
Q

Anterior and posterior chamber contain:

A

aqueous humor (produce by
ciliary body and provide nourishment
for surrounding structures)

148
Q

Where is vitreous chamber located?

A

between the ciliary body and
reina

149
Q

Vitreous chamber contains a gel-like substance
that maintains the shape of the eye
called

A

vitreous humor

Ocular Anatomy (1 decks)

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