Ocular: Osteology Or The Orbit Flashcards
1
Q
How many bones are in the skull/cranium?
A
28
2
Q
How many of the skull bones are immovable?
A
21
3
Q
The skull can be divided into what two parts:
A
-Neurocranium
-viscerocranium
4
Q
How many bones form the bony orbit/eye socket?
A
11
5
Q
The orbits are…
A
Bony cavities that each contain the globe, EOM, nerves, fat tissue, and blood vessels
6
Q
Base of the orbit is called the ________________
A
Orbital margin or orbital rim
7
Q
Dimensions of orbital margin:
A
4cm wide and 3.5cm high
8
Q
The apex of the orbit contains the…
A
Optic foramen
9
Q
Depth from the base to the apex?
A
4.5 to 5cm in depth
10
Q
Medial wall of the orbit are ____________ to each other and are ______ apart from each other
A
Parallel, 2.5cm apart
11
Q
Medial to lateral wall of the orbit lie at a ___degree angle
A
45 degrees
12
Q
Both lateral walls of the orbit lie at a ____degree angle to each other
A
90 degree angle
13
Q
Bones that form the base of the bony orbit superiorly:
A
Frontal bone
14
Q
Bones that form the base of the bony orbit inferiorly:
A
-zygomatic
-maxilla
15
Q
Bones that form the base of the bony orbit laterally:
A
-frontal
-zygomatic
16
Q
Bones that form the base of the bony orbit medially:
A
-maxilla
-frontal
17
Q
Bones that form the roof of the orbit:
A
-orbital plate of Frontal
-lesser wing of sphenoid
18
Q
Contents of the roof of the orbit:
A
-lacrimal gland fossa
-Trochlear fossa
-supraorbital foramen/notch
19
Q
Bones forming the floor of the orbit:
A
-maxilla
-zygomatic
-palatine
20
Q
Contents of the floor of the orbit:
A
Inferior orbital fissure
21
Q
Inferior orbital fissure allows for transmission of:
A
-maxillary nerve
-ascending branches from pterygopalatine ganglion
-infraorbital vessels
22
Q
Orbital floor is the __________ portion of the orbit
A
Thinnest
23
Q
Clinical signs of orbital floor fracture:
A
-crepitus
-ptosis
-enophthalmos
-strabismus
24
Q
Most common cause of orbital floor fracture
A
Blunt trauma
25
Bones forming the lateral wall of the bony orbit:
-zygomatic
-greater wing of sphenoid bone
26
Contents of lateral walls of the orbit:
-lateral orbital tubercle of the zygomatic bone
27
Whitnall’s tubercle
-lateral orbital tubercle found on the zygomatic bone
-an anchor for many structures
28
Four Ls that anchors to whitnall’s tubrecle
-lateral rectus check ligament
-Lockwood suspensory ligament
-lateral palpebral ligament
-levator aponeurosis
29
Bones forming the medial wall of the bony orbit:
-maxilla
-lacrimal
-orbital plate of ethmoid
-lesser wing of sphenoid
30
Contents of medial wall of the orbit:
-anterior and posterior ethmoidal foramina
-lacrimal groove
31
Superior orbital fissure is located between…
Greater wing of sphenoid and lesser wing of sphenoid
32
What is transmitted through the SOF?
-lacrimal nerve
-frontal nerve
-Trochlear nerve
-inferior and superior division of oculomotor nerve
-nasociliary nerve
-abducent nerve
-ophthalmic veins
33
Paranasal sinuses are:
Mucus lines air cavities within a skull bone that communicate with the nasal cavity
34
Function of paranasal sinuses
Produced mucus, lighten skull bones, act as resonance chambers
35
Frontal sinus is located in the _____________ behind the _____________________
Frontal none, superciliary arches
36
Frontal sinus opens into nasal meatus via __________
Infindibulum
37
Maxillary sinus is the __________ of the sinuses that lies within the ____________________
Largest, body of maxilla
38
Maxillary sinus communicates with the middle nasal meatus via ________________
Semilunar hiatus
39
Superior relationship to maxillary sinus
Orbit and its contents
40
Medial relationship to maxillary sinus
-Nasal cavity
-maxillary ostium located high in medial wall
41
Inferior relationship to maxillary sinus
-maxillary alveolar process
-roots of maxillary teeth
42
Temporal relationship to maxillary sinus
-bony arch of the cheek formed by connection of zygomatic and temporal bones
43
Ethmoidal air cells
-Thin-walled spaces within ethmoidal labyrinths
-cell count varies from 3-18
44
Anterior ethmoidal air cells open into…
Infundibulum of middle nasal meatus
45
Middle ethmoidal air cells open on surface of…
Ethmoidal bulla of middle nasal meatus
46
Posterior ethmoidal air cells open into…
Superior nasal meatus
47
Sphenoidal sinus are located ___________ to the upper part of the nasal cavity within the sphenoid bone
Posterior
48
Sphenoidal sinuses are related superiorly to:
-pituitary gland
-optic chiasm
49
Sphenoidal sinus is related laterally to the:
-cavernous sinus
-internal carotid artery
50
Superior boundaries of the bony orbit:
Frontal paranasal sinus and anterior cranial fossa
51
Inferior boundary of bony orbit:
Maxillary paranasal sinus
52
Lateral boundary of the bony orbit:
-Temporal fossa
-middle cranial fossa
53
Medial boundaries of the bony orbit:
-ethmoidal paranasal sinus
-sphenoid paranasal sinus
54
Lefort fractures:
Fracture patterns secondary to blunt force trauma that involve the pterygoid plate
55
Lefort fracture can result in…
A separation of the facial skeleton from the base and involve the orbit
56
Type I Lefort fracture:
-Classically occur from downward force against the upper teeth
-no portion of bony orbit is fractured
57
Type II Lefort fracture:
-from force delivered at the level of nasal bones
-portions of the medial, and inferior orbital walls are fractured
58
Type III Lefort fracture:
-From force delivered at the level of the nasal bridge and orbit
-portions of medial, lateral, and inferior orbital walls are fractured
59
5 layers of the eyelid:
1. Skin
2. Subcutaneous tissue
3. Muscular layer
4. Tarso-fascial layer
5. Conjunctiva
60
Tarso-fascial layer includes the:
-tarsal plate
-orbital septum
61
Conjunctiva is a…
Thin membrane deep to the palpebral part of the orbicularis oculi muscle
62
Conj is an extension of the _____________________ located inside and outside the bony orbit
Periosteum
63
Conj attaches to the…
Levator palpebral superioris muscle tendon in the superior eyelid and attaches to the tarsal pate of the inferior eyelid
64
Periorbita lines the bony orbit via…
Loose adherence to the bones (name change to periosteum)
65
Periorbita is continuous with the ____________ at the rim of the bony orbit
Periosteum
66
Periorbita has extensions known as _______________ which attaches…
Orbital septa, upper eyelid and lower eyelid
67
Periorbita encases the…
Contents of the bony orbit
68
Orbital cellulitis:
-infection of soft tissues of the orbit behind the orbital septum
69
Preseptal cellulitis
Infection located anterior to the orbital septum
70
Over half of orbital cellulitis infections are secondary infections from a…
Sinus infection
71
Symptoms of orbital cellulitis
Swelling
-redness
-pain, -tenderness to touch
-pain of eye movements
sometimes diplopia
72
Orbital cellulitis can lead to:
-meningitis
-loss of vision
-brain abscess
73
Four segments of the optic nerve:
-intraocular
-intraorbital
-intracanalicular
-intracranial
74
The intraocular portion of the optic nerve is the portion that:
-is evaluated by funduscope exam
-within the orbit
-1mm in length here
75
Intraorbital segment of the optic nerve starts from…
Posterior part of scleral surface until BEFORE entering the optic canal
76
Intraorbital segment is about _______ long and is the ________ portion
25-30mm, longest
77
Intraorbital being the longest is important as it allows for…
Unimpeded rotation and axial displacement
78
Intracanalicular segment of optic nerve begins at the…
Optic canal at the sphenoid bone
79
Intracanalicular segment of optic nerve is ___ long and tightly fixed to the ___________ and fuses with the ____________
9mm, dura mater, periosteum
80
Trauma to the brow can cause…
Optic neuropathy due to shifting between the dura and periosteum in the intracanalicular portion of optic nerve
81
Intracranial segment of optic nerve is _____ in length and goes all the way to the _____________
12-16mm, optic chiasm
82
Optic chiasm is about _____ wide and ____ antero-posterior in length
12mm, 8mm
83
Compact bone:
-80%
-dense
-closely packed osteons
-solid mass
84
Spongy bone:
-20%
-less dense
-consists of trabeculae and bares of bone
-irregular cavities that contain red bone marrow
85
Compact bone location:
Outer layer of bones
86
Compact bone structure
Densely packed osteons
87
Compact bone appearance
Solid and dense
88
Compact bone function
Strength and support
89
Blood supply of compact bone through…
Central canals
90
Location of compact bone in bones
Diaphysis (shaft) and outer layer
91
Location of spongy bone
Interior of bone
92
True true of spongy bone
Network of trabeculae
93
Appearance of spongy bone
Honeycomb like or spongy
94
Function of spongy bone
Metabolic needs and bone marrow production
95
Blood supply to spongy bone from….
Spaces between trabeculae
96
Location of spongy bone in bones:
Epiphysis (ends) and interior of flat/irregular bones
97
Eye muscles in the bony orbit:
-LPS
-SR
-MR
-LR
-IR
-IO
-SO
98
Nerves of the bony orbit:
-CN 2
-CN 3
-CN 4
-V1
-CN 6
99
Vessels of bony orbit:
Ophthalmic artery and veins
100
Supporting tissues of bony orbit:
-Periorbita
-muscular fascia
-ligaments
-orbital fat
101
Lacrimal contents in bony orbit:
-lacrimal gland
-lacrimal sac
-lacrimal canal
