Orbit Flashcards
(138 cards)
1
Q
ID the structure:
Resembles a 4-sided pyramid with the base anteriorly and apex posteriorly.
A
Bony orbit
2
Q
10% of all facial fractures are isolated ________ fractures.
A
Orbital wall
3
Q
___________ % of all fractures involve the orbit.
A
30-40%
4
Q
Bony Orbit superior boundary:
A
Anterior cranial fossa
5
Q
Bony Orbit inferior boundary:
A
Maxillary sinus
6
Q
Bony Orbit ______ boundary:
Nasal cavity
A
Medial
7
Q
Lateral boundary of bony orbit:
A
Middle cranial fossa and temporal fossa
8
Q
Sphenoid sinus and middle cranial fossa are ____ boundary of the bony orbit.
A
Posterior
9
Q
What CNs pass through the orbit?
A
CN II III IV V1 VI
10
Q
Name the contents of the orbit:
A
- Orbital fat
- EOMS
- Globe
- CN II III IV V1 VI
- Lacrimal apparatus
- Arteries and veins
11
Q
Name the parts of the lacrimal apparatus:
A
- Lacrimal gland
- Lacrimal sac
12
Q
Name the paired bones of the orbit:
A
- Lacrimal
- Palatine
- Zygomatic
- Maxillary
13
Q
Name the unpaired bones of the orbit:
A
- Ethmoid
- Frontal
- Sphenoid
14
Q
bony orbit is composed of ____ bones.
A
7
15
Q
Name the openings into the orbit:
A
- Superior orbital fissure
- Inferior orbital fissure
- Optic canal
16
Q
Superior orbital fissure is an opening between ______ and _____.
A
Greater and lesser wings of sphenoid
17
Q
Name the opening between greater wing of sphenoid and maxilla.
A
Inferior orbital fissure
18
Q
This opening lies between lesser wing and body of sphenoid, at the orbital apex.
A
Optic canal
19
Q
Which opening is at the orbital apex of the eye?
A
Optic canal
20
Q
The roof of the orbit underlies:
A
frontal sinus and anterior cranial fossa
21
Q
The roof of the orbit is formed by:
A
Orbital plate of frontal bone
Lesser wing of sphenoid
22
Q
Orbital plate is a thick and sturdy bone. (T/F)
A
False: it’s a very thin bone.
23
Q
Roof is thinnest at ______.
A
areas of frontal sinus
24
Q
Orbital roof anamoly/fracture is typically due to:
A
Significant head trauma
25
Unhelmeted motorcycle accidents are examples of __________ fractures.
Orbital roof
26
Possible sequelae of the orbital roof:
- CSF rinorrhea
| - Orbital encephalocele
27
What is orbital encephalocele?
Protrusion of brain through skull defect
28
The floor of the orbit is composed of:
- Orbital plate of maxillary bone
- Orbital plate of zygomatic bone
- Orbital process of palatine bone
29
Medial wall of the orbit is composed of:
- Frontal process of maxilla
- Lacrimal bone
- Orbital plate of ethmoid bone
- Body of sphenoid bone
30
Anterior + posterior lacrimal crests:
Lacrimal fossa
31
How can one get an orbital medial wall fracture?
The medial wall is extremely thin.
Prone to damage and sinusitis spread of infection.
May lead to orbital cellulitis
32
What can lead to orbital cellulitis?
Fracture/anamoly of the orbital medial wall.
33
Strongest and the thickest wall of the orbit is:
The lateral wall
34
These bones make the ______ wall of the orbit.
- Frontal process of maxilla
- Lacrimal bone
- Orbital plate of ethmoid bone
- Body of sphenoid bone
Medial
35
The lateral wall of orbit is composed of:
- Zygomatic bone
- Greater wing of sphenoid
- Zygomatic process of frontal bone
36
This bone separates orbit from temporal fossa.
Zygomatic bone
37
This bone separates orbit from middle cranial fossa.
Greater wing of sphenoid
38
Define periorbita:
All bones are lined with periorbita, which is a dense layer of vascular CT.
39
Periorbita is continuous at __________ and __________ with periosteal layer of dura.
Optic canal; superior orbital fissure
40
# Choose on:
Periorbita is loosely/firmly attached to the orbital bone.
Loosley
41
Periorbita is firmly attached to:
- Trochlea
- Optic canal
- Orbital fissures
42
What is trochlea and it's function?
Cartilaginous pulley structure for the superior oblique muscle
43
Define orbital septum:
Dense CT, extension of periobita into eyelids.
44
Orbital septum runs from ______ to ______.
Entire orbital rim to tarsal plates of eyelids
45
What is the fxn of the orbital septum?
- Barrier to spread of infection from eyelids into orbit
| - Restricts fat from falling onto the lid margins
46
This CT system is posterior to lacrimal sac:
Orbital septum
47
ID the structure:
| Runs from entire orbital rim to tarsal plates of eyelids
Orbital septum
48
Common Tendinous Ring aka
Annulus of Zinn
49
Common tendinous ring is passage for:
- Nasociliary nerve (V1)
- Oculomotor nerve (superior & inferior divisions)
- Abducens nerve
- Optic nerve
- Ophthalmic artery
50
Tenon's capsule is made of:
Dense elastic CT
51
ID the structure:
Lies between conjunctiva and episclera and merges with both at the limbus
Tenon's capsule
52
Tenon's capsule fuses with ___________ posteriorly.
Optic nerve sheath
53
What is the name of the structure that serves as a protective cover over EOM's where they insert into the sclera?
Tenon's capsule
54
What separates globe from orbital fat?
Tenon's capsule
55
Tenon's capsule functions:
- separates globe from orbital fat
| - serves as a protective cover over EOM's where they insert into the sclera
56
Name the voluntary muscles of the orbit:
- 4 recti
- 2 oblique
- lavator palpebrae superioris
57
lavator palpebrae superioris fxn:
elevates eyelid
58
_______ muscles allow for movement of globe within the orbit.
Extraocular
59
Involuntary muscle of the orbit:
Muller's muscle
60
Which muscle originates on the LPS and extends into the tarsal plates?
Muller's muscle
61
Muscle action
Lateral rectus
Abduction
62
Muscle for adduction
Medial rectus
63
Muscle for elevation, adduction, intorsion.
Superior rectus
64
Muscle for depression, adduction, extorsion
Inferior rectus
65
Muscle action
Superior oblique
Intorsion, depression, abduction
66
Muscle for extorsion, elevation, abduction
Inferior oblique
67
Field of action of each muscle is _____.
The direction where particular muscle has the greatest action
68
In lateral gaze, __________ is negated.
medial pull of SR/IR
69
In ____ gaze, lateral pull of SO/IO is negated.
Medial
70
Lavator palpebrae superioris origin and insertion
Origin: lesser wing of sphenoid bone
Insertion: superior tarsal plate and skin of eyelid
71
Elevation of eyelid is the primary action of this muscle.
Lavator palpebrae superioris
72
Primary action of superior rectus:
Elevation of globe
73
These muscles originate at common tendinous ring and insert into sclera.
superior rectus
medial rectus
inferior rectus
lateral rectus
74
Depression of the globe is done by ______.
Inferior rectus
75
Origin and insertion of inferior rectus:
Origin: common tendinous ring
Insertion: sclera
76
Primary action of lateral rectus:
Abduction of globe
77
Primary action of ________ is to adduct the globe.
Medial Rectus
78
Primary action of superior oblique:
Intorsion of globe
79
superior oblique inserts into:
sclera
80
This muscle originates from body of sphenoid above common tendinous ring:
superior oblique
81
Extorsion of globe is done by:
Inferior oblique
82
Inferior oblique origin and insertion:
Origin: orbital surface of maxilla
Insertion: sclera
83
All recti and oblique muscles insert into:
Sclera
84
These two muscle are innervated by superior division of CN III.
- Lavator palpebrae superioris
| - Superior rectus
85
IR and MR are innervated by:
Inferior division of CN III
86
This muscle is innervated by CN IV:
Superior oblique
87
These muscles are innervated by inferior division of CN III:
- Inferior rectus
- Medial rectus
- Inferior oblique
- VE to ciliary ganglion
88
CN VI innervates this muscle:
Lateral rectus
89
Secondary action of this muscle depression:
Superior oblique
90
Secondary action of inferior oblique:
Elevation
91
Adduction is the secondary action of:
Inferior rectus
| Superior rectus
92
Motor innervation of the orbit is via these CNs:
III (superior and inferior divisions), IV, VI
93
Sensory information of the orbit is via these CNs:
CN II and V1
94
Orbital blood supply is via:
Ophthalmic artery
95
venous drainage of the orbit is via:
- Superior ophthalmic vein
- Inferior ophthalmic vein
- Cavernous sinus
96
Location of superior ophthalmic vein:
Junction of supra-orbital and angular veins
97
Superior ophthalmic vein drains into:
Cavernous sinus
98
Drains into cavernous sinus or pterygoid venous plexus via IOF:
Inferior ophthalmic vein
99
Drains most of the ocular structures:
Cavernous sinus
100
What's in the ridge of superior orbital margin?
- 2 mm posterior to lateral margin: lacrimal gland fossa
| - 2 mm posterior to medial margin: trochlea
101
Floor of the orbit is separated from the lateral wall by:
Inferior orbital fissure
102
This part of the orbit connects the pterygopalatine fossa to the face:
Floor of the orbit
103
The floor of the orbit contains infraobrital canal that opens onto the face via the ___________ in order to transmit ____.
Infraorbital foramen; V2
104
The bone that is most likely to be fractured at the floor of the orbit is:
The maxillary bone
105
Orbital floor fracture can lead to:
- Prolapsed orbital fat in the maxillary sinus
- Damage to the infraorbital nerve
- IR muscle entrapment
106
Damage to the infraorbital nerve can result in:
loss of GA sensation from the cheek area of the face
107
Lamina papyracea means _______ and is another name for _________.
Paper thin; orbital plate of the ethmoid bone
108
Fossa for lacrimal sac medially is made by groove within _____________ and ____________.
lacrimal bone and frontal process of maxilla
109
Lacrimal fossa continues as _______________ to drain into the _______________.
nasolacrimal canal; inferior nasal meatus
110
______ wall fractures of the orbit normally don't need a repair.
Medial
111
Common tendinous ring is anterior/posterior to optic canal. Choose one.
Anterior
112
All recti muscles originate from:
Common tendinous ring
113
T/F:
| Both divisions of the occulomotor nerve pass through the common tendinous ring.
True
114
T/F:
| CN IV Trochlear nerve passes through the Common tendinous ring.
False. Passes through the superior orbital fissure
115
If angles of gaze and muscle coincide at 23*, elevation is done by:
Superior rectus
116
If angles of gaze and muscle coincide at 23*, ________ in done by Inferior rectus.
Depression
117
If angles of gaze and muscle coincide at 51*, ________ muscle will depress the eye.
Superior oblique
118
If angles of gaze and muscle coincide at 51*, _____________ is done by inferior oblique.
Elevation
119
Antagonist to superior rectus is:
Inferior rectus
120
Sensory innervation of the orbit is via these CNs:
- CN II
| - CN V1
121
Sensory afferent information responsible for vision is carries by:
CN II
122
General afferent from orbit, upper eyelid, superior face and forehead are carries by this CN:
CN V1
123
CN II is responsible for _____.
Vision (SA)
124
Choose one:
| CN V1 divides into 3 before/after entering the orbit.
Before
125
Frontal and lacrimal divisions of CN V1 enter the orbit via _______, ______ the tendinous ring.
SOF; above
126
______ division of CN V1 enters the orbit via SOF and passes through the common tendinous ring.
Nasociliary
127
Frontal divison of CN V1 farther divides into:
1. supratrochlear
| 2. supraorbital
128
Arterial supply to retina is via:
CRA: central retinal artery
129
Arterial supply by lacrimal artery is to:
- lacrimal gland
- conjunctiva
- eyelid
130
Short posterior ciliary arteries supply blood to:
choroid
131
Ciliary body and the iris are supplied by:
Long posterior ciliary arteries
132
Muscular branches supply:
-EOMs
133
Anterior ciliary artery branches off of ________ and supplies the _______.
Muscular branches; Iris
134
Eyebrows, forehead and the scalp are supplied by:
Supraorbital artery
135
Supratrochlear artery supplies:
Forehead and scalp
136
Anterior ethmoid artery supplies:
- Ethmoidal air cells
- frontal sinus
- nasal cavity
- external nose
137
Upper and lower eyelid arches are supplied by:
Medial palpebral artery
138
Side of the nose and lacrimal sac are supplied by:
Dorsal nasal artery
