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anatomy > G46/47: Orbit > Flashcards

G46/47: Orbit Flashcards

1
Q

The apex of the orbit

A

is the postermedial wall, superior to the optic canal

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2
Q

Base of the orbit

A

anterior orbital opening (aditus), bordered by orbital margin

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3
Q

Orbital margin is formed by

A

frontal, maxilla, zygomatic

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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

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5
Q

Anterolateral roof is marked by a groove for the

A

lacrimal gland

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6
Q

Lateral wall of the orbit is formed by

A

zygomatic and greater wing of sphenoid

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7
Q

Floor of the orbit is formed by

A

orbital surface of maxilla, orbital process of palatine, and zygomatic

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8
Q

Medial wall is formed by

A

orbital plate of ethmoid, frontal process of maxilla, lacrimal, frontal, and palatine

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9
Q

lacrimal fossa

A

formed between maxilla and lacrimal bone; fossa for the lacrimal sac

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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

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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.

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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.

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13
Q

Inferior orbital fissure

A

between maxilla and greater wing of sphenoid; between orbit and pterygopalatine fossa; transmits CN5-2 and infraorbital vessels

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14
Q

Nasolacrimal canal

A

between lacrimal and maxilla; communication between orbit and nasal cavity; houses nasolacrimal duct

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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

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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)

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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

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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

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19
Q

Palpebral fissure

A

slit between upper and lower palpebrae

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20
Q

Medial and lateral canthi

A

where the upper and lower palpebrae meet at the corners

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21
Q

Medial and Lateral palpebral ligaments

A

anchor the canthi to the bony orbital margin

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22
Q

Epicanthic fold

A

fold of skin superior to the medial angle of the eye, common to asians, young children, and Down syndrome

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23
Q

Cilia

A

eyelashes, to prevent foreign objects from entering

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24
Q

What glands open onto the ciliary follicles

A

Sebaceous glands

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25
Q

What muscle is responsible for the sphincter of the eye?

A

Orbicularis oculi

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26
Q

Levator palpebrae superioris m.

A

orbicularis oculi to skin of upper lid; opens upper eyelid; OCULOMOTOR n (CN3)

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27
Q

Tarsal muscles

A 
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
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28
Q

Ptosis cause

A

denervation to the levator palpebrae superioris (Oculomotor N), or sympathetic interruption (Horner’s Syndrome)

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29
Q

A lesion to facial n. CN7 may result in

A

inability to completely close the eye (orbicularis oculi) Bell’s Palsy

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30
Q

Tarsal plates

A

dense CT plates in upper and lower palpebrae, anchored to each other and orbital margin by MEDIAL AND LATERAL PALPEBRAL LIGAMENTS

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31
Q

What glands secrete oily substance along the eyelid rim/margins

A

Tarsal (Meibomian) glands; prevent tears from overflowing and prevent lids from sticking together

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32
Q

Hordeolum externum (STY)

A

inflammation of sebaceous glands (within the eyelash line)

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33
Q

Tarsal cyst (chalazion)

A

inflammation of the tarsal (meibomian) glands (in the eyelid)

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34
Q

Orbital septum

A

from tarsal plates to bony orbital margin; seals orbital contents from external environment

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35
Q

Conjunctival fornices

A

line of reflection between the palpebral and orbital conjunctiva

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36
Q

conjunctival sac

A

when the eye is closed, the sac that is formed between the conjunctiva

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37
Q

Lacus lacrimalis

A

triangle of reddish tissue at medial corner of eye

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38
Q

Lacrimal caruncle

A

small, distinct bump in the lacus lacrimalis

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39
Q

Semilunar fold

A

fold of conjunctiva lateral to the caruncle

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40
Q

Conjunctivitis

A

infection of the conjunctiva common in children

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41
Q

Anemia

A

pale palpebral conjunctiva

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42
Q

Bloodshot eyes

A

irritation to the bulbar conjunctiva leads to congestion of vessels

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43
Q

Lacrimal gland

A

serous gland, upper lateral corner of eye

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44
Q

Lacrimal ducts

A

drain the lacrimal gland into the superior fornix

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45
Q

Lacrimal gland in innervated by and supplied by

A

lacrimal n. (opthalmic n. branch) and lacrimal a. (branch of the opthalmic a.)

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46
Q

Parasympathetic effect of lacrimal gland?

A

Increased production; sympathetic stimulation inhibits it

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47
Q

Lacrimal puncta

A

pores located at the medial margins of the upper and lower lids, conveying tears to the lacrimal canaliculi

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48
Q

Lacrimal canaliculi

A

small ducts that convey tears to the lacrimal sac

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49
Q

Lacrimal sac

A

located within the lacrimal fossa behind the medial palpebral ligament

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50
Q

Nasolacrimal duct

A

in the nasolacrimal canal, drains tears to the nasal cavity

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51
Q

Levator palpebrae superioris origin

A

lesser wing of sphenoid, superior to optic canal

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52
Q

Levator palpebrae superioris insertion

A

superior tarsal plate and skin of eyelid

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53
Q

Levator palpebrae superioris innervation

A

oculomotor n CN3 (superior tarsal component innervated by sympathetics)

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54
Q

Levator palpebrae superioris action

A

opens eyelids

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55
Q

Rectus muscles origin

A

COMMON ANNULAR TENDON - fibrous cuff enclosing the optic canal

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56
Q

Rectus muscle insertion

A

sclera of eyeball

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57
Q

Medial rectus m.

A

Oculomotor innervation (CN3), adduction

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58
Q

Lateral rectus m.

A

abducens (CN6), abduction

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59
Q

Superior rectus m.

A

oculomotor n. (CN3), elevation, adduction, intorsion

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60
Q

Inferior rectus m.

A

oculomotor n. (CN3), depression, adduction, extorsion

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61
Q

Superior oblique m. origin

A

sphenoid body, superior to common annular tendon, medial to levator palpebrae superioris and superior rectusk

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62
Q

Superior oblique m. insertion

A

tendon enters trochlea (superomedial orbit) and inserts on superolateral sclera

63
Q

Superior oblique m. innervation

A

trochlear n. CN4)

64
Q

Superior oblique m. action

A

depression, abduction, and intorsion

65
Q

inferior oblique m. origin

A

anterior floor of orbit

66
Q

inferior oblique m. insertion

A

posterior sclera

67
Q

inferior oblique m. innervation

A

oculmotor n. (CN3)

68
Q

inferior oblique m. action

A

elevates, abduction, and extorsion

69
Q

Elevation requires what two muscles

A

inferior oblique and superior rectus

70
Q

Depression requires what two muscles

A

superior oblique and inferior rectus

71
Q

Intorsion requires what two muscles

A

superior oblique and superior rectus

72
Q

Extorsion requires what two muscles

A

inferior oblique and inferior rectus

73
Q

Optic n. (CN2)

A

sensory fibers to retinal ganglion cells

74
Q

Dural sheath of optic canal

A

continuous with the dura and fuses with the sclera

75
Q

Oculomotor n. (CN3)

A

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
Q

Superior division of oculomotor n.

A

motor to levator palpebrae superioris and superior rectus

77
Q

Inferior division of oculomotor n.

A

motor to medial rectus, inferior rectus, and inferior oblique and PREGANGLIONIC PARASYMPATHETIC FIBERS to ciliary ganglion

78
Q

Ciliary ganglion

A

located lateral to the optic n., where preganglionic parasympathetic fibers synapse (INF DIV of OCULOMOTOR N) short ciliary n exits

79
Q

Short ciliary neves

A

postsynaptic nerves (from ciliary ganglion) emerge as short ciliary nn. and innervate the sphincter pupillae and ciliary m.

80
Q

What would be the presentation of oculomotor n. damage

A

abduction, depression, ptosis and dilation of pupil

81
Q

Trochlear n.

A

wall of cavernous sinus -> superior orbital fissure, SUPERIOR TO COMMON ANNULAR TENDON; motor to superior oblique m.

82
Q

Trochlear n. palsy

A

elevation, adduction, and extorsion of affected eye, assume the trochlear torticollis

83
Q

Trochlear torticollis

A

tilt of the head away from the affected side to compensate for extorted position of eye, correcting the double vision

84
Q

Bielschowsky head-tilt

A

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
Q

Abducens n.

A

in the cavernous sinus -> superior orbital fissure THROUGH COMMON ANNULAR TENDON; motor to the lateral rectus m.

86
Q

Opthalmic n.

A

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
Q

Lacrimal n.

A

(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
Q

Frontal n.

A

(Superior to LPS and CAT) Supplies sensory superior eyelid, palpebral conjunctiva, and forehead; branches into the supraorbital and supratrochlear nn.

89
Q

Nasociliary n.

A

through the common annular tendon; gives off four branches (ganglionic branches, long ciliary n., antertior and posterior ethmoidal nn., and infratrochlear n.)

90
Q

Ganglionic branches of nasociliary

A

sensory fibers to the ciliary ganglion, short ciliary nn. carry postsynaptic and sensory to eye

91
Q

Long ciliary nn.

A

pierce eyeball near short ciliary n.; sensory to cornea, sclera, bulbar conjunctiva and carry postsynaptic sympathetic fibers to the dilator pupillae muscle

92
Q

Anterior and Posterior ethmoidal nn.

A

pass through the ethmoidal foramina, sensory to the ethmoidal air cells and sphenoid sinus

93
Q

Infratrochlear n.

A

pierces orbital septum inferior to trochlea; sensory to lacrimal apparatus, lower eyelid, and palpebral conjunctiva

94
Q

Opthalmic artery

A

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
Q

Central artery of the retina

A

opthalmic artery, courses through optic n. - supplies retina

96
Q

Ciliary arteries

A

opthalmic artery, pierces sclera with long and short ciliary nn. - supplies sclera, choroid, ciliary body, and iris

97
Q

lacrimal a.

A

opthalmic artery, runs with lacrimal n. - supplies lacrimal gland and eyelid

98
Q

anterior and posterior ethmoidal a.

A

opthalmic artery, runs with ant/pos ethmoidal nn. - sphenoid sinus and ethmoidal air cells

99
Q

supraorbital a. and supratrochlear a.

A

opthalmic artery, runs with n. - supplies eyelids, palpebral conjunctiva, and skin of forehead

100
Q

Opthalmic v.

A

superior opthalmic v. drains to cavernous sinus

inferior opthalmic v. drains to cavernous sinus pterygoid venous plexus

101
Q

Superior opthalmic v

A

exits superior orbital fissure SUPERIOR to CAT; potential route for infection because it communicates with the facial v and the cavernous sinus

102
Q

Bulbar fascia

A

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
Q

Episcleral space

A

separates the bulbar fascia from the sclera

104
Q

Suspensory ligament of the eye

A

formed inferiorly by bulbar fascia, hammock-like sling

105
Q

Enucleation

A

bulbar fascia remains intact to allow movement of prosthesis

106
Q

Sclera and cornea

A

form the outer layer tunic

107
Q

Sclera

A

dense white CT, posterior 5/6 of eyeball, pierced by optic n. and ciliary n. and vessels; continuous with nerves dural sheath

108
Q

Cornea

A

clear, colorless, avascular; anterior 1/6 of the eyeball, more curved than sclera

109
Q

corneoscleral junction

A

marked by a circular furrow (limbus) due to the extra curvature of the cornea

110
Q

corneal epithelium

A

superficial layer of cornea - continuous with the bulbar conjunctiva; deepest layer of cornea forms anterior chamber

111
Q

Sensory innervation to the cornea and sclera?

A

ciliary n. CN 5-1

112
Q

Uvea

A

intermediate vascular tunic; choroid, ciliary body, iris

113
Q

Choroid

A

darkly pigmented, vascular layer lining the sclera, adherent to retina, but separable from sclera, reduce the scattering of light within eye

114
Q

Ciliary body

A

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
Q

iris

A

adjustable pigmented diaphragm anterior to the ciliary body; pupil aperture of iris

116
Q

Muscles of the iris

A

Sphincter pupillae: annular smooth muscle, parasympathetic innervation, constricts pupil (CN3)
Dilator pupillae: radially dilate pupil - sympathetic innervation (internal carotid plexus -> long ciliary nn.)

117
Q

Optic Retina

A

neurally derived inner tunic from optic disc to ciliary body

118
Q

Pigment cell layer of retina

A

bound to choroid

119
Q

Inner neural layer of the retina

A

photoreceptive rods and cones

120
Q

macula lutea

A

high visual acuity, yellowish region; fovea centralist: center of macula with greatest visual resolution

121
Q

Optic disc

A

medial to macula, retinal ganglion cells merge as optic n. causing a blind spot and central retinal artery branches radiate

122
Q

Macular degeneration

A

central visual field deficits (common over 55)

123
Q

Dry macular degeneration

A

age-related changes in macular thickness and pigmentation

124
Q

Wet Macular degeneration

A

proliferation of choroidal blood vessels, bleeding and scarring of macula

125
Q

Ciliary and iridial retina

A

pigmented epithelium deep to the ciliary body and iris; not photoreceptive

126
Q

ora serrata

A

jagged line behind ciliary body marking the transition from non-sensory to optic retina

127
Q

Anterior chamber of the eye

A

between cornea and iris

128
Q

Posterior chamber of the eye

A

between the iris and lens

129
Q

Both anterior and posterior chambers contain

A

aqueous humor secreted from the ciliary processes, it circulates from posterior to anterior chamber through the pupillary aperture

130
Q

scleral venous sinus

A

located at the iridiocorneal angle of the anterior chamber, drains the aqueous humor

131
Q

Glaucoma

A

increase in intraocular pressure due to failure to drain aqueous humor

132
Q

Primary (open angle) glaucoma

A

insidious onset, symptomless until damage until optic n occurs

133
Q

Secondary (closed-angle) glaucoma

A

acute blockage of scleral venous sinus - pain and visual abnormalities

134
Q

Vitreous chamber

A

posterior to lens, contains vitreous body (gelatinous transparent mass) and vitreous humor, gives shape to the eyeball and holds retina in place

135
Q

Refractive media

A

transmits and refracts light; cornea principle optic surface, not physiologically adjustable; and lens

136
Q

Curvature of the cornea leads to

A

myopia (nearsightedness) and hyperopia (farsighted), astigmatism (abnormal curvature)

137
Q

Lens

A

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
Q

accommodation

A

near vision requires thickening of lens + constriction of pupil (both parasympathetic activation)

139
Q

presbyopia

A

lens loss of flexibility assuming a flatter shape causing loss of accommodation, requiring reading glasses

140
Q

Cataracts

A

clouding of the lens associated with age

141
Q

in the roof frontal sinuses lie in the

A

frontal bone

142
Q

Medial wall separates the orbit from

A

ethmoidal air cells and sphenoid sinus

143
Q

Floor separates orbit from

A

maxillary sinus

144
Q

skin of eyelid

A

thin (no fat) easily bruised

145
Q

conjunctiva

A

mucus membranes lining the deep surface of the eyelid and anterior surface of the eye (palpebral (vascularized) and bulbar( poorly vascularized))

146
Q

Lacrimal gland

A

serous gland in lateral orbital roof

147
Q

Blinking of the eyelid sweeps tears

A

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
Q

SR and IR do what

A

elevate and depress the abducted eye

149
Q

IO and SO do what

A

elevate and depress the adducted eye

150
Q

Inferior opthalmic v.

A

exits superior orbital fissure INFERIOR to CAT; drains to cavernous sinus, communicates with pterygoid venous plexus

151
Q

What separates the periorbita from bulbar fascia?

A

orbital fat

152
Q

Ciliary m. contraction

A

parasympathetic innervation, suspensory ligaments relax and lens assumes a more spherical shape for NEAR FOCUS

153
Q

Ciliary m. relaxation

A

suspensory ligaments tighten and lens resumes a flattened shape

anatomy (14 decks)

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