Eye and orbit Flashcards
(108 cards)
1
Q
what is the shape of the orbit
A
shaped like a quadrangular pyramid with its base facing anterolateral and its apex facing posteromedial.
2
Q
medial walls of the orbit are oriented how towards one another?how about the lateral walls
A
The contralateral medial orbital walls are oriented parallel to one another; while the contralateral lateral orbital walls are oriented perpendicular.
3
Q
orbital axis
A
long axis through orbitoriented at 45 degrees to one another
4
Q
optical axis
A
long axis through the globe parallel to the medial walls
5
Q
7 bones of the orbit
A
frontalethmoidlacrimalmaxillarysphenoidzygomaticpalatine
6
Q
what is the apex of orbit
A
lesser wing of sphenoid surrounding optic canal.
7
Q
what forms the base of the orbit
A
formed by the orbital margin and orbital openinga. Orbital margin is formed by frontal, zygomatic, and maxilla bones.b. Orbital margin is thickened to provide support and protection to the eyeball.
8
Q
what makes up the roof?
A
frontal bone and some sphenoid- separates orbit from anterior cranial fossafossa for lacrimal gland
9
Q
what makes up the floor
A
a. Maxilla bone – separates orbit from maxillary sinusb. Zygomatic bonec. Palatine bone
10
Q
what makes up the medial wall
A
separates orbit from sphenoidal and ethmoidal air sinusesa. Ethmoid boneb. Lacrimal bonec. Maxilla boned. The lacrimal fossa; houses the medial portion of the lacrimal system.
11
Q
what makes up the lateral wall
A
a. Zygomatic boneb. Sphenoid – greater wing
12
Q
optic canal
A
optic nerve ophthalmic artery
13
Q
superior orbital fissure
A
CN III, IV, V1, XIsuperior opthalmic vein
14
Q
inferior orbital fissure
A
inferior ophthalmic veininfraorbital artery, vein, nervezygomatic nerves
15
Q
posterior ethmoidal formanen anterior ethmoidal foramen
A
anterior ethmoidal a, v, nposterior ethmoidal a, v, n
16
Q
nasolacrimal gland
A
nasolacrimal duct
17
Q
orbital blow-out fracture
A
a massive zygomaticomaxillary fracture or a direct blow to the front of the orbitmay cause a rapid increase in intraorbital pressure and a resulting blow-out fracture of the thin orbital floor in severe comminuted fractures of the orbital floor the orbital soft tissues may herniate and blood may spread into the underlying maxillary sinusdamage to the medial walls–> sphenoidal or ethmoidal air sinusesdamage to roof- anterior cranial fossaclinical signs include diplopia, infraorbital nerve paresthesia, enopthlamamos (sinking in eye), edema, eccymosis, detached retina, weakest part is the floor
18
Q
where is the most likely fracture site in a blow out fracture
A
inferior and medial orbital walls
19
Q
orbital tumor
A
- Malignant tumors originating in the sphenoidal and ethmoidal sinuses, middle cranial, or infratemporal fossa can erode through the thin walls of the orbit or pass directly through foramina. These tumors can compress the orbital contents.2. Can cause exophthalmos.
20
Q
what are 4 fascias of the orbit
A
periorbital fasciamuscular fasciacheck ligamentsfascial sheath of eyeball (Tenon’s capsule)
21
Q
periorbital fascia
A
lines bones of orbit.a. Continuous with periosteal dura at optic canal and superior orbital fissure.b. Continuous with the orbital septum anteriorly.c. Continuous with muscular fascias of extraocular eye muscles.
22
Q
muscular fascia
A
surrounds extraocular eye muscles
23
Q
check ligaments
A
a. Medial and lateral; attach to medial and lateral orbital walls.b. Limit abduction and adduction of the eye.c. Prevent posterior retraction of the eyeball by the rectus muscles.
24
Q
fascial sheath of the eyeball (Tenon’s capsule)
A
a. Thin membrane surrounding eyeball; external to sclera. b. Continuous with the muscular fascia of the extraocular eye muscles.c. Separates eyeball from orbital fat.
25
what is the role of orbital fatwhat happens in starvation
a. Cushionb. Lubrication c. Protection d. CLINICAL CORRELATION: With starvation, the eyes often become sunken-in (enophthalmos) due to loss of orbital fat.
26
what are the 5 layers of supporting structures of the eye
skinloose CTmuscular layer (orbicularis oculi and levator palpebrae superioris) tarsal plate- dense CT palpebral conjunctiva - epithelium
27
what is the function of the eyelid
protection; spread lacrimal fluid to lubricate cornea.
28
what does the tarsal plate insert onto
orbital septum - fibrous membrane connecting tarsi to margins of orbit functions to contain orbital fat within the orbit, also helps limit the spread of infections b/w face and orbit
29
what is the function of the medial palpebral ligamentlateral palpebral ligament?
3. Medial palpebral ligament – connect tarsi to medial wall of orbit.4. Lateral palpebral ligament – connect tarsi to lateral wall of orbit.
30
palpebral conjunctiva
epithelium of internal eyelid
31
bulbar conjunctiva
outer epithelium of sclera
32
what is the conjuntival sac
between palpebral and bulbar conjunctiva; opens at palpebral fissure.
33
what is the conjunctival fornices
(superior and inferior) are formed where bulbar and palpebral conjunctiva are continuous.
34
what is the lacrimal glandwhere is itwhat does it do
a. Compound tubuloalveolar glandb. Located in lacrimal fossa in superolateral orbit.c. Secretes lacrimal fluid – watery, serous secretion – into conjunctival sac.d. Lacrimal fluid keeps sclera and cornea moist and contains an antibacterial agent for protection.
35
where are the lacrimal cannaliculi
a. Located in medial angle of eye.b. Begin at the lacrimal papilla; the lacrimal punctum is the opening
36
what is the lacrimal sac
receives fluid from lacrimal cannaliculi
37
what is the nasolacrimal duct
drains lacrimal fluid to nasal cavity
38
what is the flow of tears
lacrimal gland → conjunctival sac → surface of eye → lacrimal papillae with puncta → cannaliculae → lacrimal sac→ nasolacrimal duct
39
what are the components of the external fibrous tunicwhat is corneal neovascularization
1. Sclera a. Tough, opaque fibrous layer covering posterior 5/6 of globe.b. Provides structural support for eye and provides for muscle attachment.2. Cornea a. Avascular, dehydrated, transparent layer covering anterior 1/6 of globe.b. Provides most of eye’s refractile capabilities.c. Numerous pain receptors located within cornead. CLINICAL CORRELATION: Corneal neovascularization = blood vessels grow into corneal stroma secondary to hypoxia.
40
what are the components of the middle vascular tunic (uvea)
choroidirisciliary body
41
what is the choroid
a. Highly vascularized, loose connective tissue; located deep to sclera.b. Provides vascular supply to fibrous layers and outermost layers of retina.c. Contains melanocytes which produce melanin to absorb photons of light.
42
what is the iriswhat are the muscles of the iris
a. Central aperture forms pupil; controls the amount of light entering the pupil.b. Muscles 1. Sphincter pupillaea. Reduces diameter of pupil (miosis) to decrease light entering eye.b. Parasympathetic innervation (CN III).2. Dilator pupillaea. Increases diameter of pupil (mydriasis) to increase light entering eye.b. Sympathetic innervation.
43
what is the ciliary body and what are its two main functions
ciliary processes and ciliary muscle 1. secrete aqueous humor2. accommodation
44
what are the ciliary processes what do they secrete
1. Finger-like extensions from ciliary body.2. Secrete aqueous humor into posterior chamber.3. Suspensory ligaments (zonule fibers) extend from ciliary processes to len.
45
what is the ciliary muscle what is it innervated bywhat is its function
1. Parasympathetic innervation (CN III)2. Accommodationa. Control of lens thickness via suspensory ligaments.b. When looking at distant objects, the ciliary muscle is relaxed and there is tension on the suspensory ligaments of the lens. The ciliary processes pull on the lens and cause it to be stretched and thinned.c. When focusing on near objects, the ciliary muscle contracts. The ciliary muscle pulls the ciliary body medially and anteriorly and reduces tension on suspensory ligaments. Less tension on the suspensory ligaments means that the lens becomes rounded and thicker.d. No stimulation – lens is thin and flat to focus distant.e. Parasympathetic stimulation (CN III) – lens round to focus near.
46
inner neural tunic is what
the retinathere are 10 layers (look at heck's lecture)
47
what do the ganglion cells that are in the retina form
will form the optic nerve
48
what is the ora serrata
anterior termination of the retina
49
what is the optic disc
– located on the posterior pole of globe. Represents site of entry of optic nerve (CN II) and the central retinal artery and vein. No photoreceptive cells.blind spot
50
what is the macula lutea
a yellow-pigmented zone located about 2.5 mm lateral to optic disk.
51
what is the fovea centralis
– oval depression located in the central of the macula. Site of greatest visual acuity due to density of cone cells.
52
what is the blood supply to the retina
a. Central retinal artery supplies neural portion of retina (except rods/cones).b. Choroid vessels supplies pigmented epithelium and rod/cone layer
53
how does retinal detachment occur and what can be the result of this
Retinal detachment occurs when the pigmented epithelium separates from the underlying rods and cones layer. Detachment can cause blindness if not corrected immediately due to loss of metabolic support and blood supply to rods and cones.
54
what is the lens and what is its function
1. Transparent, refractile, flexible, biconvex disk located posterior to iris.2. Function: Refraction (focusing light) and accommodation
55
what is presbyopia
hardening (loss of elasticity) of the lens inability to accomodate and focus on near objects
56
what are cataracts
develop when the proteins of the lens aggregate producing opaque lens
57
where is the aqueous anterior chamber
b/w cornea and iris
58
where is the posterior chamber
b/w iris and lens
59
what is aqueous humorwhere is it producedwhere does it flowwhere does it drain and via what
1. Refractive fluid filling anterior and posterior chambers.2. Produced in posterior chamber by ciliary processes of ciliary body.3. Flows from posterior chamber to anterior chamber via pupil.4. Drains to venous system via the scleral venous sinus (Canal of Schlemm) at the iridocorneal angle. The scleral venous sinus is covered by a trabecular meshwork (endothelial lined spaces) which helps drain aqueous humor.5. Scleral venous sinus drains to vorticose and anterior ciliary veins.
60
what is glaucoma
Glaucoma is a condition caused by excess aqueous humor in the anterior and posterior chambers. Most often due to decreased outflow of aqueous humor (failure to drain due to blockage of scleral venous sinus) or from increased production of aqueous humor. Glaucoma results in increased intraocular pressure; can cause blindness if left untreated.
61
where is the vitreous body
b/w lens and posterior surface of the eye filled with vitrous humor--> a transparent refractile jelly-like substance
62
what is exopthalmos
a. Protrusion of eyeball from orbit.b. Seen in certain diseases such as hyperthyroidism, orbital tumors.
63
what is enopthalamos
a. Protrusion of eyeball from orbit.b. Seen in certain diseases such as hyperthyroidism, orbital tumors.
64
what is the main artery that supplies the orbit and the eye itselfwhere does this artery enter the orbit
ophthalmic artery (branch of internal artery) enters orbit via the optic canal
65
what does ciliary mean in terms of arteries
going to the eye itself (usually outer layers)
66
what are the branches off the ophthalmic artery (11)
central retinal arteryshorter posterior ciliarylong posterior ciliary anterior ciliary lacrimasupraorbital posterior ethmoidal anterior ethmoidalmedial palpebral supratrochleardorsal nasal
67
central retinal artery
1. Pierces optic sheath and runs within optic nerve. 2. Supplies inner layers of retina (except rods/cones and pigmented epithelium layers).
68
short posterior ciliary arteries
pierce sclera near optic nerve to supply choroid.
69
long posterior ciliary arteries
pierce sclera anteriorly to supply ciliary body/iris.
70
anterior ciliary arteries
arise from muscular branches; to ciliary body and iris.
71
lacrimal artery
to lacrimal gland and lateral portions of eyelids
72
supraorbital artery
to forehead and scalp
73
medial plpebral a.
medial eyelids
74
supratrochlear
to forehead and scalp
75
dorsal nasal
supplies dorsal surface of nose
76
where does the central retinal vein drain
directly to cavernous sinus
77
what does the vorticose vein drain
B. Vorticose veins drain the choroid, ciliary body, and iris.
78
what do superior and inferior ophthlamic veins drain
C. Superior and inferior ophthalmic veins – exit orbit via superior and inferior orbital fissures (respectively). Drain to cavernous sinus and pterygoid venous plexus (respectively).
79
what can happen with thrombophlebitis of the cavernous sinus
D. CLINICAL CORRELATION – Thrombophlebitis of the cavernous sinus may send a clot to the central retinal vein; may lead to vision loss.
80
what can increased ICP do to the eye
Increased intracranial pressure can affect the eye due to the fact that the meninges and CSF continue along the optic nerve. Thus, the optic nerve, central retinal artery, and central retinal vein can be compressed and occluded.
81
occlusion of the central retinal vein
papilledema (retinal edema)
82
compression of the optic nerve
blindness
83
retinal artery occlusion can cause what
blindness due to loss of blood supply to the retina
84
what are the 6 movements of the eye
A. Adduction – movement of the pupil towards midline (toward nose)B. Abduction – movement of pupil laterally (toward ear, vertical axis)C. Elevation – movement of pupil superiorly.(transverse axis) D. Depression – movement of pupil inferiorlyE. Extortion – superior pole of eyeball rotated laterally. (to ear) F. Intortion – superior pole of eyeball rotated medially.(to nose) No control of rotation of the eye !! that is vestibular control
85
what are the 7 extraocular eyes muscles
levator palpebrae superioris medial rectuslateral rectussuperior rectusinferior rectusinferior oblique superior oblique
86
medial rectus origininsertionfunctioninnervationtesting integrity
1. Origin – common tendinous ring2. Insertion – medial surface of eyeball3. Function – adducts eye4. Innervation – CN III5. Testing integrity – eye held in abducted position; loss of adduction.
87
lateral rectus origininsertionfunctioninnervationtesting integrity
1. Origin – common tendinous ring.2. Insertion – lateral surface of the eyeball3. Function – abducts eye.4. Innervation – CN VI5. Testing integrity – eye held in adducted position; loss of abduction
88
Superior rectus origininsertionfunctioninnervationtesting integrity
1. Origin – common tendinous ring2. Insertion – superior surface of eyeball3. Function – elevates, adducts; intorsion4. Innervation – CN III5. Testing integrity – weakness of elevation; loss of elevation when eye is fully abducted.
89
inferior rectusorigininsertionfunction
innervation
testing integrity
1. Origin – common tendinous ring2. Insertion – inferior surface of eyeball3. Function – depresses, adducts; extorsion4. Innervation – CN III5. Testing integrity – weakness of depression; loss of depression when eye is fully abducted.
90
inferior oblique origininsertionfunctioninnervationtesting integrity
1. Origin – anterior portion of floor of orbit2. Insertion – inferior surface of eyeball, posterior to the equator (vertical axis) 3. Function – elevates, abducts; extorsion.4. Innervation – CN III5. Testing integrity – weakness of elevation; loss of elevation when eye is fully adducted.
91
superior obliqueorigininsertionfunctioninnervationtesting integrity
1. Origin – common tendinous ring2. Insertion – superior surface of eyeball, posterior to the equator (vertical axis)3. This muscle passes through a trochea and changes its direction to attach to the eyeball.4. Function – depresses, abducts; intorsion.5. Innervation – CN IVtesting ability- weakness of depression; loss of depression when eye is fully adducted
92
how do we look up?
superior rectus and inferior oblique
93
how do we look down
superior oblique and inferior rectus
94
go to eye website from funks lecture
do it UC Davis?also see funks slide 59-60
95
are images depicting functions of EO muscles and how you test the clinically different?
yes
96
testing lateral rectus clinically
have patient abduct their eye
97
testing medial rectus clinically
have the patient adduct their eye
98
testing superior rectus
Superior rectus – have patient abduct their eye and then elevate.
99
testing inferior rectus
Inferior rectus – have patient abduct their eye and then depress. this is because in this plane when the eye is abducted the only muscle that could depress the eye is the inferior rectus
100
how do we test the superior oblique
Superior oblique – have patient adduct their eye and then depress.
101
how do we test the inferior oblique
Inferior oblique – have patient adduct their eye and then elevate.
102
what 6 of the CN's are associated with the orbit
CNII SSA (optic canal) through superior orbital fissureCN III GSE, GVE-PCN IV GSECN V1 GSACN VI GSECNVII SVE to orbicularis oculi
103
LR6SO4R3
Lateral rectus CN VI
Superior oblique CN IV
All the rest CN III
104
what three nerves are responsible for innervating the EO eye muscles
CN VICN IVCN III
105
CN III does what muscles
levator palpebrae superioris
medial, superior, inferior rectus
and inferior oblique
106
CN IV
superior oblique
107
CN VI
lateral rectus
108
what are the 5 nerves in the orbit? and what are their components
what is a sixth nerve that isn't in the orbit but is associated with the eye?
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CN II – SSA
CN III – GSE; GVE-P
CN IV – GSE
CN V1 – GSA
CN VI – GSE
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CN VII SVE to orbicularis oris
