G46/47: Orbit Flashcards
(153 cards)
1
Q
The apex of the orbit
A
is the postermedial wall, superior to the optic canal
2
Q
Base of the orbit
A
anterior orbital opening (aditus), bordered by orbital margin
3
Q
Orbital margin is formed by
A
frontal, maxilla, zygomatic
4
Q
Roof of the orbit is formed by
A
orbital plate of frontal, lesser wing of sphenoid; frontal sinus intervenes between orbit and anterior fossa
5
Q
Anterolateral roof is marked by a groove for the
A
lacrimal gland
6
Q
Lateral wall of the orbit is formed by
A
zygomatic and greater wing of sphenoid
7
Q
Floor of the orbit is formed by
A
orbital surface of maxilla, orbital process of palatine, and zygomatic
8
Q
Medial wall is formed by
A
orbital plate of ethmoid, frontal process of maxilla, lacrimal, frontal, and palatine
9
Q
lacrimal fossa
A
formed between maxilla and lacrimal bone; fossa for the lacrimal sac
10
Q
Blowout fracture
A
increased intraorbital pressure from a blow to the eye that causes a fracture to the medial or inferior orbital wall
11
Q
Optic canal
A
between body and lesser wing of sphenoid; communication with orbit and middle cranial fossa; Transmits optic n (CN2) and opthalmic a.
12
Q
Superior orbital fissure
A
between greater and lesser wing of sphenoid; communication bw middle cranial fossa and orbit; Transmits Oculomotor (CN3), Trochlear n. (CN4), Opthalmic div of Trigeminal n. (CN5-1) and Abducens (CN6) branches of opthalmic v.
13
Q
Inferior orbital fissure
A
between maxilla and greater wing of sphenoid; between orbit and pterygopalatine fossa; transmits CN5-2 and infraorbital vessels
14
Q
Nasolacrimal canal
A
between lacrimal and maxilla; communication between orbit and nasal cavity; houses nasolacrimal duct
15
Q
Anterior and posterior ethmoidal foramina
A
near frontoethmoidal sutures, communication between orbit and ethmoidal air cells, transmitting anterior and posterior ethmoidal nerves and vessels
16
Q
Orbital axis
A
from apex to center of the base; 45 degrees between R/L axis (medial walls of orbits are parallel and lateral walls are at 90 degrees)
17
Q
Optic axis
A
long axis of the eye from cornea to lateral side of optic disc; R/L parallel to median wall and primary optic gazer
18
Q
Periorbita
A
periosteal lining of the orbit (sheath surrounding fat, nerves, vessels,muscle, and eyeball) fuses with ENDOSTEAL layer of dura mater and DURAL SHEATH of optic n. and PERIOSTEUM of bones forming orbital margin
19
Q
Palpebral fissure
A
slit between upper and lower palpebrae
20
Q
Medial and lateral canthi
A
where the upper and lower palpebrae meet at the corners
21
Q
Medial and Lateral palpebral ligaments
A
anchor the canthi to the bony orbital margin
22
Q
Epicanthic fold
A
fold of skin superior to the medial angle of the eye, common to asians, young children, and Down syndrome
23
Q
Cilia
A
eyelashes, to prevent foreign objects from entering
24
Q
What glands open onto the ciliary follicles
A
Sebaceous glands
25
What muscle is responsible for the sphincter of the eye?
Orbicularis oculi
26
Levator palpebrae superioris m.
orbicularis oculi to skin of upper lid; opens upper eyelid; OCULOMOTOR n (CN3)
27
Tarsal muscles
```
sympathetic innervation (internal carotid plexus); derived from deep layer of levator palpebrae superioris; smooth muscle inserting on upper and lower tarsal plates, elevates/depresses eyelids
Horner's Syndrome: ptosis
```
28
Ptosis cause
denervation to the levator palpebrae superioris (Oculomotor N), or sympathetic interruption (Horner's Syndrome)
29
A lesion to facial n. CN7 may result in
inability to completely close the eye (orbicularis oculi) Bell's Palsy
30
Tarsal plates
dense CT plates in upper and lower palpebrae, anchored to each other and orbital margin by MEDIAL AND LATERAL PALPEBRAL LIGAMENTS
31
What glands secrete oily substance along the eyelid rim/margins
Tarsal (Meibomian) glands; prevent tears from overflowing and prevent lids from sticking together
32
Hordeolum externum (STY)
inflammation of sebaceous glands (within the eyelash line)
33
Tarsal cyst (chalazion)
inflammation of the tarsal (meibomian) glands (in the eyelid)
34
Orbital septum
from tarsal plates to bony orbital margin; seals orbital contents from external environment
35
Conjunctival fornices
line of reflection between the palpebral and orbital conjunctiva
36
conjunctival sac
when the eye is closed, the sac that is formed between the conjunctiva
37
Lacus lacrimalis
triangle of reddish tissue at medial corner of eye
38
Lacrimal caruncle
small, distinct bump in the lacus lacrimalis
39
Semilunar fold
fold of conjunctiva lateral to the caruncle
40
Conjunctivitis
infection of the conjunctiva common in children
41
Anemia
pale palpebral conjunctiva
42
Bloodshot eyes
irritation to the bulbar conjunctiva leads to congestion of vessels
43
Lacrimal gland
serous gland, upper lateral corner of eye
44
Lacrimal ducts
drain the lacrimal gland into the superior fornix
45
Lacrimal gland in innervated by and supplied by
lacrimal n. (opthalmic n. branch) and lacrimal a. (branch of the opthalmic a.)
46
Parasympathetic effect of lacrimal gland?
Increased production; sympathetic stimulation inhibits it
47
Lacrimal puncta
pores located at the medial margins of the upper and lower lids, conveying tears to the lacrimal canaliculi
48
Lacrimal canaliculi
small ducts that convey tears to the lacrimal sac
49
Lacrimal sac
located within the lacrimal fossa behind the medial palpebral ligament
50
Nasolacrimal duct
in the nasolacrimal canal, drains tears to the nasal cavity
51
Levator palpebrae superioris origin
lesser wing of sphenoid, superior to optic canal
52
Levator palpebrae superioris insertion
superior tarsal plate and skin of eyelid
53
Levator palpebrae superioris innervation
oculomotor n CN3 (superior tarsal component innervated by sympathetics)
54
Levator palpebrae superioris action
opens eyelids
55
Rectus muscles origin
COMMON ANNULAR TENDON - fibrous cuff enclosing the optic canal
56
Rectus muscle insertion
sclera of eyeball
57
Medial rectus m.
Oculomotor innervation (CN3), adduction
58
Lateral rectus m.
abducens (CN6), abduction
59
Superior rectus m.
oculomotor n. (CN3), elevation, adduction, intorsion
60
Inferior rectus m.
oculomotor n. (CN3), depression, adduction, extorsion
61
Superior oblique m. origin
sphenoid body, superior to common annular tendon, medial to levator palpebrae superioris and superior rectusk
62
Superior oblique m. insertion
tendon enters trochlea (superomedial orbit) and inserts on superolateral sclera
63
Superior oblique m. innervation
trochlear n. CN4)
64
Superior oblique m. action
depression, abduction, and intorsion
65
inferior oblique m. origin
anterior floor of orbit
66
inferior oblique m. insertion
posterior sclera
67
inferior oblique m. innervation
oculmotor n. (CN3)
68
inferior oblique m. action
elevates, abduction, and extorsion
69
Elevation requires what two muscles
inferior oblique and superior rectus
70
Depression requires what two muscles
superior oblique and inferior rectus
71
Intorsion requires what two muscles
superior oblique and superior rectus
72
Extorsion requires what two muscles
inferior oblique and inferior rectus
73
Optic n. (CN2)
sensory fibers to retinal ganglion cells
74
Dural sheath of optic canal
continuous with the dura and fuses with the sclera
75
Oculomotor n. (CN3)
motor to EOM, parasympathetic to intrinsic eye; wall of cavernous sinus to superior orbital fissure; superior and inferior branches THROUGH THE COMMON ANNULAR TENDON
76
Superior division of oculomotor n.
motor to levator palpebrae superioris and superior rectus
77
Inferior division of oculomotor n.
motor to medial rectus, inferior rectus, and inferior oblique and PREGANGLIONIC PARASYMPATHETIC FIBERS to ciliary ganglion
78
Ciliary ganglion
located lateral to the optic n., where preganglionic parasympathetic fibers synapse (INF DIV of OCULOMOTOR N) short ciliary n exits
79
Short ciliary neves
postsynaptic nerves (from ciliary ganglion) emerge as short ciliary nn. and innervate the sphincter pupillae and ciliary m.
80
What would be the presentation of oculomotor n. damage
abduction, depression, ptosis and dilation of pupil
81
Trochlear n.
wall of cavernous sinus -> superior orbital fissure, SUPERIOR TO COMMON ANNULAR TENDON; motor to superior oblique m.
82
Trochlear n. palsy
elevation, adduction, and extorsion of affected eye, assume the trochlear torticollis
83
Trochlear torticollis
tilt of the head away from the affected side to compensate for extorted position of eye, correcting the double vision
84
Bielschowsky head-tilt
tilting head toward the affected side in trochlear palsy causes compensatory contraction of superior rectus causes elevation of affected eye, allowing you to diagnose the palsy
85
Abducens n.
in the cavernous sinus -> superior orbital fissure THROUGH COMMON ANNULAR TENDON; motor to the lateral rectus m.
86
Opthalmic n.
supplies sensory to the orbital structures and skin of face; gives off three branches (lacrimal, frontal, and nasociliary) though lateral wall of cavernous sinus through superior orbital fissure
87
Lacrimal n.
(lateral to LPS and superior to CAT) branch of the opthalmic n.; sensory to the lacrimal gland, superior eyelid, palpebral conjunctiva, conveys postsynaptic autonomic innervation to lacrimal gland from CN5-2
88
Frontal n.
(Superior to LPS and CAT) Supplies sensory superior eyelid, palpebral conjunctiva, and forehead; branches into the supraorbital and supratrochlear nn.
89
Nasociliary n.
through the common annular tendon; gives off four branches (ganglionic branches, long ciliary n., antertior and posterior ethmoidal nn., and infratrochlear n.)
90
Ganglionic branches of nasociliary
sensory fibers to the ciliary ganglion, short ciliary nn. carry postsynaptic and sensory to eye
91
Long ciliary nn.
pierce eyeball near short ciliary n.; sensory to cornea, sclera, bulbar conjunctiva and carry postsynaptic sympathetic fibers to the dilator pupillae muscle
92
Anterior and Posterior ethmoidal nn.
pass through the ethmoidal foramina, sensory to the ethmoidal air cells and sphenoid sinus
93
Infratrochlear n.
pierces orbital septum inferior to trochlea; sensory to lacrimal apparatus, lower eyelid, and palpebral conjunctiva
94
Opthalmic artery
internal carotid, with optic n, gives off three branches (central artery of the retina, ciliary arteries, non-ocular branches - lacrimal, anterior and posterior ethmoidal, supraorbital and supratrochlear)
95
Central artery of the retina
opthalmic artery, courses through optic n. - supplies retina
96
Ciliary arteries
opthalmic artery, pierces sclera with long and short ciliary nn. - supplies sclera, choroid, ciliary body, and iris
97
lacrimal a.
opthalmic artery, runs with lacrimal n. - supplies lacrimal gland and eyelid
98
anterior and posterior ethmoidal a.
opthalmic artery, runs with ant/pos ethmoidal nn. - sphenoid sinus and ethmoidal air cells
99
supraorbital a. and supratrochlear a.
opthalmic artery, runs with n. - supplies eyelids, palpebral conjunctiva, and skin of forehead
100
Opthalmic v.
superior opthalmic v. drains to cavernous sinus
| inferior opthalmic v. drains to cavernous sinus pterygoid venous plexus
101
Superior opthalmic v
exits superior orbital fissure SUPERIOR to CAT; potential route for infection because it communicates with the facial v and the cavernous sinus
102
Bulbar fascia
CT sheath suspending the eyeball within the orbit, continuous with the dural sheath of the optic n and fuses with the sclera, pierced by EOMs and gives a CT sheath to tendons
103
Episcleral space
separates the bulbar fascia from the sclera
104
Suspensory ligament of the eye
formed inferiorly by bulbar fascia, hammock-like sling
105
Enucleation
bulbar fascia remains intact to allow movement of prosthesis
106
Sclera and cornea
form the outer layer tunic
107
Sclera
dense white CT, posterior 5/6 of eyeball, pierced by optic n. and ciliary n. and vessels; continuous with nerves dural sheath
108
Cornea
clear, colorless, avascular; anterior 1/6 of the eyeball, more curved than sclera
109
corneoscleral junction
marked by a circular furrow (limbus) due to the extra curvature of the cornea
110
corneal epithelium
superficial layer of cornea - continuous with the bulbar conjunctiva; deepest layer of cornea forms anterior chamber
111
Sensory innervation to the cornea and sclera?
ciliary n. CN 5-1
112
Uvea
intermediate vascular tunic; choroid, ciliary body, iris
113
Choroid
darkly pigmented, vascular layer lining the sclera, adherent to retina, but separable from sclera, reduce the scattering of light within eye
114
Ciliary body
ring-shaped structure, continuous posteriorly with choroid; with ciliary muscle surrounding iris (parasympathetic control) ciliary processes suspensory ligament of lens, secrete aqueous humor to fill the chambers of the eye and ciliary zonule the ring of suspensory ligaments
115
iris
adjustable pigmented diaphragm anterior to the ciliary body; pupil aperture of iris
116
Muscles of the iris
Sphincter pupillae: annular smooth muscle, parasympathetic innervation, constricts pupil (CN3)
Dilator pupillae: radially dilate pupil - sympathetic innervation (internal carotid plexus -> long ciliary nn.)
117
Optic Retina
neurally derived inner tunic from optic disc to ciliary body
118
Pigment cell layer of retina
bound to choroid
119
Inner neural layer of the retina
photoreceptive rods and cones
120
macula lutea
high visual acuity, yellowish region; fovea centralist: center of macula with greatest visual resolution
121
Optic disc
medial to macula, retinal ganglion cells merge as optic n. causing a blind spot and central retinal artery branches radiate
122
Macular degeneration
central visual field deficits (common over 55)
123
Dry macular degeneration
age-related changes in macular thickness and pigmentation
124
Wet Macular degeneration
proliferation of choroidal blood vessels, bleeding and scarring of macula
125
Ciliary and iridial retina
pigmented epithelium deep to the ciliary body and iris; not photoreceptive
126
ora serrata
jagged line behind ciliary body marking the transition from non-sensory to optic retina
127
Anterior chamber of the eye
between cornea and iris
128
Posterior chamber of the eye
between the iris and lens
129
Both anterior and posterior chambers contain
aqueous humor secreted from the ciliary processes, it circulates from posterior to anterior chamber through the pupillary aperture
130
scleral venous sinus
located at the iridiocorneal angle of the anterior chamber, drains the aqueous humor
131
Glaucoma
increase in intraocular pressure due to failure to drain aqueous humor
132
Primary (open angle) glaucoma
insidious onset, symptomless until damage until optic n occurs
133
Secondary (closed-angle) glaucoma
acute blockage of scleral venous sinus - pain and visual abnormalities
134
Vitreous chamber
posterior to lens, contains vitreous body (gelatinous transparent mass) and vitreous humor, gives shape to the eyeball and holds retina in place
135
Refractive media
transmits and refracts light; cornea principle optic surface, not physiologically adjustable; and lens
136
Curvature of the cornea leads to
myopia (nearsightedness) and hyperopia (farsighted), astigmatism (abnormal curvature)
137
Lens
between iris and vitreous body, biconvex, suspended from ciliary body by suspensory ligaments, thickness and shape are adjusted by the ciliary muscle (flatten and rounded shape)
138
accommodation
near vision requires thickening of lens + constriction of pupil (both parasympathetic activation)
139
presbyopia
lens loss of flexibility assuming a flatter shape causing loss of accommodation, requiring reading glasses
140
Cataracts
clouding of the lens associated with age
141
in the roof frontal sinuses lie in the
frontal bone
142
Medial wall separates the orbit from
ethmoidal air cells and sphenoid sinus
143
Floor separates orbit from
maxillary sinus
144
skin of eyelid
thin (no fat) easily bruised
145
conjunctiva
mucus membranes lining the deep surface of the eyelid and anterior surface of the eye (palpebral (vascularized) and bulbar( poorly vascularized))
146
Lacrimal gland
serous gland in lateral orbital roof
147
Blinking of the eyelid sweeps tears
inferior and medially to the lacus lacrimalis, rapid blinking compresses the lacrimal sac against the median palpebral ligament and sniffling is caused by flow of tears into the nasal cavity
148
SR and IR do what
elevate and depress the abducted eye
149
IO and SO do what
elevate and depress the adducted eye
150
Inferior opthalmic v.
exits superior orbital fissure INFERIOR to CAT; drains to cavernous sinus, communicates with pterygoid venous plexus
151
What separates the periorbita from bulbar fascia?
orbital fat
152
Ciliary m. contraction
parasympathetic innervation, suspensory ligaments relax and lens assumes a more spherical shape for NEAR FOCUS
153
Ciliary m. relaxation
suspensory ligaments tighten and lens resumes a flattened shape
