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Anatomy > head: orbit > Flashcards

head: orbit Flashcards

1
Q

orbit: Pyramid-shaped w/ ________ base +________ apex

A

Anterolateral base

Posteromedial apex

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2
Q

what angles are the medial and lateral walls of the orbit to each other?

A

Medial walls parallel

Lateral walls at 90° to each other

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3
Q

what angles are the axis of the orbits at to each other? what about axis of neutral gaze?

A

Axis of orbits at 45° to each other

Axis of neutral gaze parallel

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4
Q

what lines the orbit?

A

Lined by periorbita-periosteum of orbit

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5
Q

what bones make up the orbit opening of the face (aka the base) ?

A

Reinforced portions of frontal, zygomatic, & maxillary bones

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6
Q

what make up the superior wall of the orbit?

A

Orbital portion of frontal bone

Lesser wing of sphenoid

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7
Q

what bone can you find the anterolateral fossa for lacrimal gland?

A

orbital portion of frontal bone (forming the superior wall)

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8
Q

where bones are the superior and inferior orbital fissures between? what wall does each separate in the orbit?

A

superior orbital fissure: optic canal between lesser and greater wings of sphenoid (separates lateral wall from apex)
inferior orbital fissure: between maxilla and greater sphenoid (separates lateral wall from inferior wall)

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9
Q

what 4 bones make up the median wall of the orbit?

A

Orbital plate of ethmoid
Frontal process of maxillary bone
Lacrimal bone
Frontal bone

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10
Q

what are the two features on the medial wall of the orbit?

A

lacrimal bone: fossa for nasolacrimal duct

attachment of trochlea for superior oblique

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11
Q

what bones makes up the inferior wall of the orbit?

A

maxillary

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12
Q

which is the most exposed portion of the orbit (which wall)?

A

lateral

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13
Q

what bones make up the lateral wall of the orbit?

A

Frontal process of zygomatic bone

Greater wing of sphenoid

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14
Q

what is the apex of the pyramid that is the orbit ?

A

Optic canal in lesser wing of sphenoid

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15
Q

what is the palpebra conjunctiva? what does it reflect onto?

A

internal lining of eyelid (palpebra)

Reflects onto anterior surface of eyeball

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16
Q

which conjunctiva is directly on the sclera and attaches to it from the border of the cornea?

A

bulbar conjunctiva (vascular)

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17
Q

what is the space between the palpebra + bulbar conjunctiva . what is the significance of this location?

A 
Conjunctival sacs (superior & inferior)
- where you administer eyedrops
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18
Q

what is the “tarus”? what do they do?

A

on inner side of eyelid: Dense connective tissue containing tarsal glands
Secrete lipid to prevent sticking & resist tear drainage

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19
Q

orbital septs extend from _____ to _______ ______. what is their purpose?

A

Orbital septa extend from tarsus to orbital margin

Limits spread of infection to/from orbit to face (act as barrier)

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20
Q

what muscle is anterior/superficial to tarsus? (on eyelid)

A

Palpebral portion of orbicularis oculi

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21
Q

what are the medial and lateral canthus of the eye?

A

Palpebral commissures-medial & lateral junctions

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22
Q

medial/lateral palpebral ligaments extends from where to where? what is the significance of the medial palpebral ligament?

A

from medial/lateral canthus out to orbital margin(bone)

- Origin & insertion of orbicularis oculi

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23
Q

what 4 structures does the “lacrimal apparatus” include?

A
  • lacrimal gland
  • 2 lacrimal papillae
  • lacrimal sac
  • nasolacrimal duct
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24
Q

lacrimal gland: where is it? what does it contain? what is its purpose?

A

Fossa of superolateral orbit
8-12 excretory ducts drain into superior conjunctival sac
(Isotonic saline with lysozyme)
Lubricates conjunctiva & cornea

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25
Q

what do the lacrimal papillae/canaliculi do?

A

Drain tears from lacrimal lake at medial canthus

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26
Q

what is the path of secretomotor innervation of the lacrimal apparatus? ( pregang, enters where and becomes what nerve, synapses, postgang)

A

PSNS
Preganglionic fibers travel in CN VII (Greater petrosal branch)
Enters pterygoid canal as nerve of pterygoid canal
Synapse in pterygopalatine ganglion (synapse occurs here)
Postganglionic fibers travel in CN V2, then CN V1. after synapse…
CN V2- Infra-orbital
CNV2 -Zygomatic
CN V1 - Lacrimal

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27
Q

eye muscles: which two do elevation, which two do depression?

A

inferior oblique and superior rectus: elevation

inferior rectus and superior oblique : depression

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28
Q

what is the most superior muscle in the orbit space?

A

Levator Palpebrae Superioris

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29
Q

Levator Palpebrae Superioris: O, I, A, Inn

A

O-lesser wing of sphenoid, superior to optic canal
I-tarsus & skin of superior lid
A- Elevates superior lid
Inn- oculomotor nerve (CN III)

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30
Q

superior oblique: O, I, A, In

A

O-body of sphenoid, tendon redirected by trochlea in superomedial orbit
I-lateral sclera (deep to superior rectus)
A- Abducts, depresses, medially rotates eyeball- summation of abduct and depress = DOWN + OUT
Main action-depression of pupil when adducted
Inn: trochlear nerve (CN IV)

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31
Q

what is the only eye muscle innervated by trochlear CN IV ( not oculomotor nerve CN III)

A

superior oblique

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32
Q

what 3 axises does the eye move around?

A

vertical, transverse, AP

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33
Q

inferior oblique muscle: O, I, A, Inn

A

O-anterior portion of orbital floor near lacrimal fossa of lacrimal bone
I-lateral sclera (deep to lateral rectus)
A- Abducts, elevates, laterally rotates eyeball
Main action-elevation of pupil when abducted
“UP + OUT”
Inn- oculomotor nerve (CN III)

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34
Q

superior rectus muscle: O, I, A, Inn

A

O-common tendinous ring around optic canal & portion of superior orbital fissure
I-superior sclera
A- Elevates, adducts, medially rotates eyeball -UP + IN
Main action-elevation of pupil
Inne- oculomotor nerve (CN III)

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35
Q

inferior rectus muscle: O,I,A, Inn

A

O-common tendinous ring around optic canal & portion of superior orbital fissure
I-inferior sclera
A- Depresses, adducts, laterally rotates pupil - DOWN + IN
Main action-depression of pupil
Inn- oculomotor nerve (CN III)

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36
Q

which is the only eye muscle innervated by abducent nerve (CN VI) ( and not oculomotor nerve CN III)

A

lateral rectus

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37
Q

medial rectus muscle: O, I, A, In

A

O-common tendinous ring
I-medial sclera
A- Adducts eyeball
Inn- oculomotor nerve (CN III)

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38
Q

lateral rectus muscle: O, I, A, In

A

O-common tendinous ring
I-lateral sclera
A- Abducts eyeball
Inn- abducent nerve (CN VI)

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39
Q

what eye muscles of movement originate on the common tendinous ring around optic canal?

A

sup. and inf rectus, medial and lateral rectus

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40
Q

where do all eye muscles for movement insert?

A

somewhere on the sclera

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41
Q

what is the “common tendinous ring” of the orbit?

A

Tendons of 4 rectus muscles enclose portion of superior orbital fissure

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42
Q

what are the contents of the “common tendinous ring” ? (5)

A
  1. Optic nerve (CN II)
  2. Ophthalmic artery
  3. Superior/inferior divisions of oculomotor nerve (CN III)
  4. Abducent nerve (CN VI)
  5. Nasociliary nerve (terminal branch of ophthalmic (CN V1) nerve)
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43
Q

what does the nasocilliary nerve do?

A

from CN V1: Sensory from cornea & sympathetic motor to dilator pupillae

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44
Q

eye movement tests: Initially directing gaze _______ isolates SR for ____, IR for________

A

laterally (along axis of SR/IR)
SR: elevation
IR: depression

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45
Q

IO (due to….) & SO (due to …) approach eyeball laterally.

A

IO: anterior origin
AO: redirection by trochlea

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46
Q

eye movement test: Initially directing gaze______ isolates SO for _______, IO for _______

A

medially (along axis of SO/IO)
SO: depression
IO: elevation

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47
Q

Tests: what are the directions to test: SO, IO, SR, IR ?

A

SO- IN and down
IO- IN and up
SR- OUT and up
IR - OUT and down

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48
Q

eyeball: what portion of the orbit does it occupy? about how big is it?

A

Occupies anterior 1/3 of orbit

Approximately 2.5 cm diameter

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49
Q

what prevents retraction of the eyeball into the posterior 2/3 of the orbit?

A

Retrobulbar fat prevents retraction (inophthalmous)

50
Q

what is the eyeball suspended in?

A

Suspended in fascial sheath (Tenon’s capsule) & by bulbar conjunctiva

51
Q

what three spherical layers/tunics surround the hollow globe that is the eyeball? what structures do each include?

A

Fibrous layer- sclera + cornea
Vascular layer-uvea: Choroid, ciliary body, & iris
Neural layer-retina

52
Q

what is the fibrous layer of the eye like? what are the portions of sclera + cornea?

A

Tough, provides shape & resistance

sclera ( posterior 5/6) cornea ( anterior 1/6)

53
Q

sclera portion of fibrous layer: what is it like? attachments for what 2 kinds of structures?

A

Opaque, visible through bulbar conjunctiva

Attachment of intrinsic & extraocular muscles

54
Q

cornea portion of fibrous layer: what is it like?

A

Transparent, convex
Avascular, highly innervated (nasociliary branch of CN V1)
Nutrients derived from lacrimal fluid & aqueous humor

55
Q

what is the function of the cornea ?

A

Functions in refraction of light entering eyeball

56
Q

vascular layer: choroid

A

Choroid-lines most of posterior sclera
Highly vascular (highest perfusion)
Neural retina derives nutrients from choroid capillaries

57
Q

vascular layer: ciliary body - what is it? what 2 things does it do?

A

Ring of smooth muscle

  • Controls thickness of lens via zonular fibers (suspensory ligament of lens)
  • Ciliary processes secrete aqueous humor
58
Q

what is the anterior continuation of the choroid?

A

ciliary body

59
Q

vascular layer: iris- what is it? what does it do?

A

most anterior aspect of choroid
Contractile diaphragm with central aperture (pupil)
Regulates light entering eyeball

60
Q

what are the two muscles that are directly under the iris (and help it do its function)

A

outer radial muscles: dilator pupillae - SNS

inner circular muscles: sphincter pupillae - PSNS

61
Q

outer radial muscles (dilator pupillae): SNS or PSNS? fxn? fast or slow?

A 
Sympathetic stimulation
Dilates pupil (mydriasis)
Paradoxically slow
62
Q

inner circular muscles (sphincter pupillae): SNS or PSNS? fxn? fast or slow?

A 
Parasympathetic stimulation
Constricts pupil (miosis)
Paradoxically immediate
63
Q

two parts of the neural layer/tunic? what areas do each line?

A

optic retina: lines posterior eyeball to ciliary body (“fundus”)
nonoptic retina: lines ciliary body & iris

64
Q

neural layer: optic retina - two layers

A

Light-receptive neural layer (external & avascular)

Light absorbing pigmented layer (internal, contains retinal artery)

65
Q

neural layer: nonoptic retina- one layer

A

Only pigmented layer

66
Q

two features of the neural layer/tunic

A

optic disc + maculae lutea

67
Q

optic disc: where is it? what is it?

A

Medial (nasal) portion of fundus
Entry of optic nerve & retinal vessels
No photoreceptors, “blind spot”

68
Q

maculae lutea: where is it? what is it?

A

Lateral to optic disc, direct axis from pupil
Highly concentrated cones
Fovea centralis-center of macula

69
Q

where is the fovea centralis? what is its significance

A

center of macula - highest visual acuity

70
Q

what are the compartments of the eye? where does each extend? what type of liquid in each?

A

anterior: between cornea + lens - filled w/ aqueous humor
posterior: between lens + retina - filled w/ vitreous body

71
Q

what is the anterior compartment subdivided into?

A

Subdivided by iris into anterior & posterior chambers

Continuous via pupil

72
Q

anterior compartment: what produces aqueous humor, what absorbs it?

A

Ciliary processes in posterior chamber produce aqueous humor

Scleral venous sinus (canal of Schlemm) in anterior chamber absorbs aqueous humor

73
Q

Intraocular pressure dictated by rates of what?

A

rates of production + absorption of aqueous humor

74
Q

what does the vitreous body of the posterior comparment do?

A

Transmits light to retina & absorbs excess light

Supports lens position

75
Q

define refraction

A

Bending of light rays to focus on retina

76
Q

what do the cornea + lens each do in refraction?

A

Cornea-major refractive medium, focuses inverted/reversed image

Lens-fine-tunes refraction

77
Q

what is the shape of the lens? what is it suspended by?

A

Biconvex, transparent

Suspended by zonular fibers of ciliary body

78
Q

how do you get distant vision?

A

Relaxed ciliary body tenses zonular fibers, stretches lens to less convex

79
Q

how do you get near vision (accommodation)?

A

Contracted ciliary body relaxes zonular fibers, lens relaxes to more convex

80
Q

what innervates for near vision?

A

Parasympathetic via oculomotor nerve

81
Q

what nerves enter the orbit?

A

CN II- VI

*(CN V includes V1 and V2)

82
Q

CN II

A

visual stimuli to visual cortex (special sensory)

83
Q

CN III: somatic + autonomic

A

motor to levator palpebrae superioris, SR, MR, IR, & IO (**all except SO) (somatic motor)
preganglionic PSNS to ciliary ganglion (autonomic)

84
Q

CN IV : somatic

A

motor to SO (somatic motor)

85
Q

CN V: V1 : somatic + autonomic

A

sensory from face, cornea (somatic sensory); postganglionic PSNS to lacrimal gland, ciliary body, & sphincter pupillae (autonomic);
postganglionic SNS to dilator pupillae (autonomic)

86
Q

CN V: V2 : somatic + autnomic

A

sensory from face & scalp (somatic sensory); postganglionic PSNS to lacrimal gland (autonomic)

87
Q

CN VI : somatic

A

motor to LR (somatic motor)

88
Q

which nerves do somatic motor?

A

CN III, IV, VI

89
Q

what is the course of optic nerve CN II ? - enters orbit via?, passes through (maintaining what covering)? pierces what? enters retina where?

A

Enters via optic canal
Passes through tendinous ring of rectus muscles
Maintain meningeal covering & CSF (optic nerve sheath)
Pierce sclera at lamina cribrosa
Enters retina at optic disc

90
Q

Optic nerve sheath pierced by what?

A

central artery of retina

91
Q

where does oculomotor CN III enter the orbit? what does it divide into?

A

Enters via superior orbital fissure
Divides into superior & inferior divisions
*Both divisions pass through tendinous ring of rectus muscles

92
Q

CN III superior division - supplies what two muscles?

A

Levator palpebrae superioris

Superior rectus

93
Q

CN III inferior division - supplies what 3 muscles, what autonomics?

A

Medial rectus
Inferior rectus
Inferior oblique
Preganglionic parasympathetic to ciliary ganglion (ciliary body & sphincter pupillae)

94
Q

course of trochlear nerve CN IV

A

Enters via superior orbital fissure
DOES NOT pass through tendinous ring of rectus muscles
Supplies superior oblique

95
Q

course of abducens nerve CN VI

A

Enters via superior orbital fissure
Passes through tendinous ring of rectus muscles
Supplies lateral rectus

96
Q

which is the only nerve that does NOT pass through tendinous ring of rectus muscles?

A

trochlear nerve CN IV

97
Q

opthalmic nerve CN V1 - what does it supply?

A

Sensory from upper face & scalp
Sensory from cornea
Conveys postganglionic parasympathetic neurons to lacrimal gland

98
Q

what are the division of CN V1

A

Three divisions, all pass through orbit
Frontal
Lacrimal
Nasociliary

99
Q

CN V1: frontal nerve : course, what it divides into, what it supplies

A

Courses along roof of orbit
Divides into supratrochlear & supraorbital branches
exits Supraorbital foramen
Supplies portions of face & scalp

100
Q

CN V1: lacrimal nerve : course? receives fibers from what nerve?

A

Courses along roof of orbit to reach lacrimal gland & overlying skin
Receives postganglionic PSNS fibers from pterygopalatine ganglion via zygomatic nerve of CN V2

101
Q

which is the only portion of CN V1 to pass through the tendinous ring with rectus muscles?

A

CN V1: nasociliary nerve

102
Q

CN V1: nasociliary nerve: divides into what 3 branches?

A

Divides into infratrochlear, ethmoidal, & sensory branches from cornea

103
Q

CN V1: nasociliary nerve: sensory fibers from cornea divide into what?

A
  1. Some fibers pass through ciliary ganglion, enter short ciliary nerve
  2. Some fibers bypass ciliary ganglion, enter long ciliary nerve
    - Long ciliary also carries SNS neurons to dilator pupillae
104
Q

Long ciliary nerves carry sensory fibers from cornea (nasociliary nerve) but ALSO carry what?

A

SNS neurons to dilator pupillae

105
Q

ciliary ganglion: SNS or PSNS?

A

PSNS

106
Q

three “roots” that enter the ciliary ganglion. what do they each supply?

A
  1. Nasociliary-some sensory neurons of CN V1 from cornea
  2. SNS-vasomotor to eyeball
  3. PSNS (oculomotor)-preganglionic neurons from CN III
107
Q

ciliary ganglion- what nerves synapse and leave? what just pass through it?

A

synapse: PSNS (oculomotor) enter ganglion-> synapse w/ short ciliary-> Postganglionic PSNS neurons to ciliary body & sphincter pupillae
just pass through: Continuation of SNS & sensory nasociliary neurons (no synapse)

108
Q

maxillary nerve CN V2: what does it supply? delivers postgang from where?

A

Sensory from mid-face, upper jaw, & anterolateral scalp

-Delivers postganglionic PSNS neurons from pterygopalatine ganglion to lacrimal nerve (CN V1)

109
Q

what two division of maxillary nerve CN V2 pass through orbit?

A

Infraorbital

Zygomatic

110
Q

CN V2 infraorbital nerve: course + supply

A

Enters via inferior orbital fissure
No branches to eye
Exits via infraorbital foramen
Supplies mid-face & upper jaw

111
Q

CN V2 zygomatic: where does it enter + supply ?

A

Enters via inferior orbital fissure

Supply anterolateral face & scalp

112
Q

CN V2: zygomatic subdivides into what?

A

Divides into zygomaticotemporal & zygomaticofacial branches

113
Q

CN V2: zygmogatic nerve has a communicating branch with what nerve? what does it carry in this?

A

Communicating branch to lacrimal nerve (CN V1)

Postganglionic parasympathetic fibers

114
Q

ophthalmic artery: what is it a branch of? where does it enter the orbit?

A

Branch of internal carotid

Enters via optic foramen

115
Q

what branches come off the ophthalmic artery in the orbit?

A
  1. Central artery of retina pierces sheath of optic nerve
    Only supply to inner retina
  2. Long & short ciliary braches supply other layers
116
Q

pupil reactivity: what nerve is the afferent? efferent?

A

CN II afferent, CN III efferent (constriction)

117
Q

corneal reflex/blink reflex: what is it? afferent/efferent nerves? what does it assess?

A

Somatic protective reflex
**Contact cornea (overlying iris/pupil), not sclera (“white of eye”)
CN V1 afferent, CN VII efferent (orbicularis oculi)
Assessment of brain death or neurologic exam

118
Q

what is horner syndrome

A

Unilateral miosis, ptosis, & anhydrosis
Constricted pupil, drooping of eyelid, & absence of sweating
Unilateral interruption of sympathetic innervation of head

119
Q

presbyopia

A

Lens stiffens, less rounding with ciliary body contraction
Inability to focus on near objects
Hold books at a distance, reading glasses

120
Q

glaucoma: open vs closed angle

A

Open angle: Dysfunction or obstruction of scleral venous sinuses
Closed angle: Iris buckles & obstructs outflow
Worsened by anticholinergics

Anatomy (13 decks)

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