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134 Cards in this Set

  • Front
  • Back
General contents of the orbit
eyeball, muscles, neurovascular and lacrimal apparatus structures, orbital fat, ciliary ganglion, optic nerve
Which bones is the orbit of the eye comprised of?
frontal, sphenoid, ethmoid, lacrimal, maxilla, palatine, zygomatic bones
Osteology: what is the name of the part of the maxilla which extends superiorly by the nasal and frontal bone?
frontal process of the maxilla
Osteology: what is the name of the part of the maxilla which extends deep toward the superior orbital fissure?
orbital process of the maxilla
Which wing of the sphenoid bone is found in the orbit of the eye?
greater wing
What are the apertures of the orbit?
base (outer), superior orbital fissure, inferior orbital fissure, optic canal (apex)
In the orbit, what is the name of the indentation on the lacrimal bone?
lacrimal fossa
What is the name of the groove in the orbit?
Infraorbital groove
What aperture of the orbit is the apex?
the optic canal
What are the functions of the eyelids?
cover the eyeball anteriorly
-protect it from excessive light and foreign objects
-help spread lacrimal fluid to keep cornea moist
Eyelids are covered externally by what and internally by what
externally--skin
internally-palpebral conjunctiva
The lacrimal apparatus consists of what?
lacrimal glands,
ducts,
papilla/punctum,
canaliculi,
sac,
nasolacrimal duct
What stimulates lacrimal fluid?
parasympathetic from CN VII
What fluid is responsible for keeping the eyeball moist?
lacrimal fluid
The palpebral conjunctiva is continuous with what which covers the sclera and cornea?
bulbar conjunctiva
palpebral conjunctiva and bulbar conjunctiva meet where?
At the superior and inferior fornices (singular: fornix)
What is the name of the medial fold of conjunctiva near the lacrimal lake?
plica semilunaris
Describe the iris
lies on anterior surface of lens
is a thin, contractile diaphragm with a central aperature (pupil)
The diameter of the pupil (controlling transmission of light) is controlled by what?
sphincter pupillae and dilator pupillae
eyelids are strengthened by dense bands of connective tissue known as:
tarsal plates
tarsal plates connected to the medial and lateral angles of the eye by what?
the medial and lateral palpebral ligaments
What is the name of the weak membrane that spans from the tarsal plates to the margins of the orbit where it eventually becomes continuous with the periosteum
orbital septum
Eyelids have 5 layers. What are they?
outer skin layer
subcutaneous layer
muscular layer
tarsofacial layer
conjunctival layer
What are the muscles found in the eyelid
palpebral part of the orbicularis oculi
levator palpebrae superioris
What is contains within the tarsofacial layer?
tarsal glands and plate
What is the conjunctival layer of the eyelid?
palpebral conjunctiva
lacrimal gland split into two parts by what?
a lateral expansion of the levator palpebrae superioris m.
Describe course of drainage of tears.
lacrimal gland--> lacrimal ducts--> superior and inferior fornices-->lacrimal lake --> lacrimal punctum on the lacrimal papilla-->lacrimal canaliculi--> lacrimal sac--> nasolacrimal duct--> inferior nasal meatus of nasal cavity
mound of modified skin tissue found in the lacrimal lake is called what?
lacrimal caruncle
Bones forming the orbit are lined with what (name the periosteum)
periorbita
What forms the fascial sheath of the eyeball
periorbita
The fascial sheath of the eyeball is also known as
bulbar sheath or Tenon's capsule
Expansions of the fascial sheath at the medial and lateral rectus muscles are called what?
medial and lateral check ligaments
The blending of the check ligaments with the fascia of the inferior rectus and inferior oblique muscles is called what?
suspensory ligament
the fascial sheath is pierced by the tendons of extraocular muscles and is reflected onto each of them as what?
tubular (muscle) sheath
What is the function of medial and lateral check ligaments?
They limit adduction and abduction respectively
What is the function of the suspensory ligament
supports the eyeball and limits downward displacement
How many extraocular muscles are there and what are their names
7
levator palpebrae superioris
superior rectus
inferior rectus
medial rectus
lateral rectus
superior oblique
inferior oblique
All extraocular muscles, except superior oblique and lateral rectus, are innervated by which nerve
CN III (oculomotor n.)
Origin of levator palpebrae superioris
lesser wing of sphenoid
insertion of levator palpebrae superioris
upper eyelid and superior tarsal plate
innervation of levator palpebrae superioris
CN III (superior division); superior tarsal muscle is innervated by VE- symp/post fibers
function of levator palpebrae superioris
elevates upper eyelid
Origin of superior rectus
common tendinous ring (annulus of Zinn)
Insertion of superior rectus
superior sclera
innervation of superior rectus
CN III (superior division)
action of superior rectus
elevate, adduct and medially rotate eyeball
origin of inferior rectus
common tendinous ring (annulus of Zinn)
Insertion of inferior rectus
inferior sclera
innervation of inferior rectus
CN III (inferior division)
action of inferior rectus
depress, adduct and laterally rotate eyeball
origin of medial rectus
common tendinous ring (annulus of Zinn)
insertion of medial rectus
medial sclera
innervation of medial rectus
CN III (inferior division)
action of medial rectus
adducts eyeball
origin of lateral rectus
common tendinous ring (annulus of Zinn)
insertion of lateral rectus
lateral sclera
innervation of lateral rectus
CN VI (abducens nerve)
action of lateral rectus
abduct eyeball
origin of superior oblique
body of sphenoid bone
insertion of superior oblique
superior sclera deep to superior rectus
innervation of superior oblique
CN IV trochlear nerve
action of superior oblique
abducts, depresses and medially rotates eyeball
What is a trochlea?
a fibrous ring that acts like a pulley
origin of inferior oblique
anteromedial floor of orbit
insertion of inferior oblique
sclera inferior to lateral rectus
innervation of inferior oblique
CN III (inferior division)
action of inferior oblique
abducts, elevates, and laterally rotates eyeball
optical and orbital axis deviate by how many degrees?
23 degrees
Point of maximum visual acuity
fovea centralis
where is the fovea centralis in relation to the blind spot created by the optical disk?
lateral to it.
What are the two muscles responsible for elevating the eyeball?
superior rectus and inferior oblique
movemnet of the eyeball occurs at three different axes of rotation
anteroposterior, horizontal and vertical axes
elevation of the eyeball occurs at which axis?
horizontal axis
What are the two muscles responsible for depressing the eyeball?
inferior rectus and superior oblique
depression of the eyeball occurs at which axis?
horizontal axis
What are the three muscles responsible for abducting the eyeball?
lateral rectus, inferior oblique, and superior oblique
abduction movement occurs at which axis?
vertical axis
What are the three muscles responsible for adducting the eyeball?
medial rectus
inferior rectus
superior rectus
adduction movement occurs at which axis?
vertical axis
which two muscles are responsible for laterally rotating the eyeball?
inferior oblique and inferior rectus
movement of lateral rotation occurs at which axis?
anteroposterior axis
movement of medial rotation occurs at which axis?
anteroposterior axis
which two muscles are responsible for laterally rotating the eyeball?
superior oblique and superior rectus
What are the nerves of the orbit?
CN II (optic)
CN III (oculomotor)
CN IV (trochlear)
CN VI (abducens)
CN V1 (ophthalmic division)
...and their branches
CN V1 supplies has what fibers and innervates what?
SA fibers...supplies face and ethmoidal air cell mucosa
What goes through the optic canal?
CN II (optic n.)
ophthalmic a. and v.
The Optic nerve is surrounded by what
meninges (all 3)
The optic nerve is pierced by what?
the central artery of the retina
Describe CN III's VE Para fibers' path from brain to target
Edinger-Westphal nucleus in the midbrain--> cilliary ganglion-->short ciliary nerves--> ciliary body and sphincter pupillae muscles
CN V1 or ophthalmic n. divides into 3 branches:
frontal, lacrimal, and nasociliary ns.
V1's SA cell bodies are where?
Trigeminal ganglion
frontal branches of V1 divides into two nerves
supraorbital and supratrochlear ns.
nasociliary n. gives rise to:
long ciliary, posterior and anterior ethmoidal ns and then changes names to become the infratrochlear n.
relationships of ciliary ganglion
lateral edge of optic nerve near the lateral rectus muscle
What are the 3 roots of the ciliary ganglion?
1. motor root para/pre (CN III inferior division)
2. sensory root: SA fibers from eyeball which join V1
3. sympathetic root (sym/post fibers from superior cervical ganglion via carotid plexus--courses with ophthalmic a. into orbit)
anterior ethmoidal n. of nasociliary branch give off what nerve?
external nasal
What is the main blood supply to the orbit?
ophthalmic a.
what are the sympathetic splanchnic nerves to the GIT?
thoracic, lumbar
Where does the ophthalmic a. enter the orbit?
optic canal
What are the branches of the orbit?
central artery of the retina, lacrimal, long/short posterior ciliary, supraorbital, posterior and anterior ethmoidal, dorsal nasal, and supratrochlear.
Veins corresponding to ophthalmic artery branches, along with inferior ophthalmic vein drain into what vein and then into what sinus?
into the superior ophthalmic vein which leads to the cavernous sinus
the inferior ophthalmic vein also drains into the pterygoid venous plexus which drains into the cavernous sinus
Which artery pierces the optic nerve?
The central artery of the retina
eyeball consists of three layer or "tunics" which are?
fibrous (outer) layer, vascular (pigmented) layer or uvea, and inner (retinal) layer
what are the refractive media of the ey?
cornea, aqueous humor, lens, and vitreous humor
fibrous (outer) layer consists of what?
cornea and sclera
cornea covers how much of the eyeball?
1/6
cornea is responsbile for what
refracts light entering eye
sclera covers how much of eye and does what?
posterior 5/6 of eyeball and provides shape and attachment sites for muscles
vascular (pigmented) layer (or uvea) consists of what
choroid, ciliary body, and iris
choroid has 2 layers
outer pigmented layer and inner highly vascularized layer
function of choroid
nourish the retina
function of ciliary body
muscular--controls thickness of lens
vascular
connects choroid and iris
attachment for lens
ciliary processes secrete aqueous humor
ciliary muscle innervated by what fibers?
VE para/post
contration and relaxation of smooth muscle of ciliary muscle controls thickness of lens...result in?
focus or accommodation
what secretes aqueous humor?
ciliary processes of the ciliary body
aqueous humor fills what areas?
anterior and posterior chambers
which two muscles in the iris control the size of the pupil?
sphincter (constrictor) pupillae and dilator pupillae
Sphincter pupillae innervated by what fibers?
VE para/post
dilator pupillae innervated by what fibers
VE symp/post
retina has what layers?
outer pigmented and inner neural layers
Which retinal layer is the light receptor
neural layer
what are the 3 types of neurons in the neural layer of the retina
rods and cones
bipolar neurons
ganglion neurons--axons of these form the optic nerve
function of pigmented layer of the retina?
reinforces the light absorbing property of the choroid by reducing light scattering
circular area where teh optic nerve and central retina vessels are found
optic disc--no photoreceptors and is insensitive to light
yellow spot of retina
macula lutea
area of most acute vision in eye
fovea centralis
posterior part of eyeball
fundus
cornea
function: refraction
transparent
avascular
sensitive to touch
supplied by V1 fibers of the ciliary nerves
what attaches lens to ciliary bodies?
zonular fibers
which side of the lens changes the most to focus of accommodate?
anterior surface
What separates the anterior and posterior chambers of the eye
iris
posterior to the lens is what
vitreous chamber
function of vitreous humor
holds retina in place, supports lens, transmits light