Eye and Orbit (FUNK) Flashcards
what is the shape of the orbit
shaped like a quadrangular pyramid with its base facing anterolateral and its apex facing posteromedial.
medial walls of the orbit are oriented how towards one another?
how about the lateral walls
The contralateral medial orbital walls are oriented parallel to one another; while the contralateral lateral orbital walls are oriented perpendicular.
orbital axis
long axis through orbit
oriented at 45 degrees to one another
optical axis
long axis through the globe
parallel to the medial walls
7 bones of the orbit
frontal ethmoid lacrimal maxillary sphenoid zygomatic palatine
what is the apex of orbit
lesser wing of sphenoid surrounding optic canal.
what forms the base of the orbit
formed by the orbital margin and orbital opening
a. Orbital margin is formed by frontal, zygomatic, and maxilla bones.
b. Orbital margin is thickened to provide support and protection to the eyeball.
what makes up the roof?
frontal bone and some sphenoid- separates orbit from anterior cranial fossa
fossa for lacrimal gland
what makes up the floor
a. Maxilla bone – separates orbit from maxillary sinus
b. Zygomatic bone
c. Palatine bone
what makes up the medial wall
separates orbit from sphenoidal and ethmoidal air sinuses
a. Ethmoid bone
b. Lacrimal bone
c. Maxilla bone
d. The lacrimal fossa; houses the medial portion of the lacrimal system.
what makes up the lateral wall
a. Zygomatic bone
b. Sphenoid – greater wing
optic canal
optic nerve
ophthalmic artery
superior orbital fissure
CN III, IV, V1, XI
superior opthalmic vein
inferior orbital fissure
inferior ophthalmic vein
infraorbital artery, vein, nerve
zygomatic nerves
posterior ethmoidal formanen anterior ethmoidal foramen
anterior ethmoidal a, v, n
posterior ethmoidal a, v, n
nasolacrimal gland
nasolacrimal duct
orbital blow-out fracture
a massive zygomaticomaxillary fracture or a direct blow to the front of the orbit
may 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 sinus
damage to the medial walls–> sphenoidal or ethmoidal air sinuses
damage to roof- anterior cranial fossa
clinical signs include diplopia, infraorbital nerve paresthesia, enopthlamamos (sinking in eye), edema, eccymosis, detached retina,
weakest part is the floor
where is the most likely fracture site in a blow out fracture
inferior and medial orbital walls
orbital tumor
- 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.
- Can cause exophthalmos.
what are 4 fascias of the orbit
periorbital fascia
muscular fascia
check ligaments
fascial sheath of eyeball (Tenon’s capsule)
periorbital fascia
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.
muscular fascia
surrounds extraocular eye muscles
check ligaments
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.
fascial sheath of the eyeball (Tenon’s capsule)
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.
what is the role of orbital fat
what happens in starvation
a. Cushion
b. Lubrication
c. Protection
d. CLINICAL CORRELATION: With starvation, the eyes often become sunken-in (enophthalmos) due to loss of orbital fat.
what are the 5 layers of supporting structures of the eye
skin
loose CT
muscular layer (orbicularis oculi and levator palpebrae superioris)
tarsal plate- dense CT
palpebral conjunctiva - epithelium
what is the function of the eyelid
protection; spread lacrimal fluid to lubricate cornea.
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
what is the function of the medial palpebral ligament
lateral palpebral ligament?
- Medial palpebral ligament – connect tarsi to medial wall of orbit.
- Lateral palpebral ligament – connect tarsi to lateral wall of orbit.
palpebral conjunctiva
epithelium of internal eyelid
bulbar conjunctiva
outer epithelium of sclera
what is the conjuntival sac
between palpebral and bulbar conjunctiva; opens at palpebral fissure.
what is the conjunctival fornices
(superior and inferior) are formed where bulbar and palpebral conjunctiva are continuous.
what is the lacrimal gland
where is it
what does it do
a. Compound tubuloalveolar gland
b. 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.
where are the lacrimal cannaliculi
a. Located in medial angle of eye.
b. Begin at the lacrimal papilla; the lacrimal punctum is the opening
what is the lacrimal sac
receives fluid from lacrimal cannaliculi
what is the nasolacrimal duct
drains lacrimal fluid to nasal cavity
what is the flow of tears
lacrimal gland → conjunctival sac → surface of eye → lacrimal papillae with puncta → cannaliculae → lacrimal sac→ nasolacrimal duct
what are the components of the external fibrous tunic
what is corneal neovascularization
- Sclera
a. Tough, opaque fibrous layer covering posterior 5/6 of globe.
b. Provides structural support for eye and provides for muscle attachment. - 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 cornea
d. CLINICAL CORRELATION: Corneal neovascularization = blood vessels grow into corneal stroma secondary to hypoxia.
what are the components of the middle vascular tunic (uvea)
choroid
iris
ciliary body
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.
what is the iris
what are the muscles of the iris
a. Central aperture forms pupil; controls the amount of light entering the pupil.
b. Muscles
- Sphincter pupillae
a. Reduces diameter of pupil (miosis) to decrease light entering eye.
b. Parasympathetic innervation (CN III). - Dilator pupillae
a. Increases diameter of pupil (mydriasis) to increase light entering eye.
b. Sympathetic innervation.
what is the ciliary body and what are its two main functions
ciliary processes and ciliary muscle
- secrete aqueous humor
- accommodation
what are the ciliary processes what do they secrete
- Finger-like extensions from ciliary body.
- Secrete aqueous humor into posterior chamber.
- Suspensory ligaments (zonule fibers) extend from ciliary processes to len.
what is the ciliary muscle
what is it innervated by
what is its function
- Parasympathetic innervation (CN III)
- Accommodation
a. 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.
inner neural tunic is what
the retina
there are 10 layers (look at heck’s lecture)
what do the ganglion cells that are in the retina form
will form the optic nerve
what is the ora serrata
anterior termination of the retina
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
what is the macula lutea
a yellow-pigmented zone located about 2.5 mm lateral to optic disk.
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.
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
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.
what is the lens and what is its function
- Transparent, refractile, flexible, biconvex disk located posterior to iris.
- Function: Refraction (focusing light) and accommodation
what is presbyopia
hardening (loss of elasticity) of the lens
inability to accomodate and focus on near objects
what are cataracts
develop when the proteins of the lens aggregate producing opaque lens
where is the aqueous anterior chamber
b/w cornea and iris
where is the posterior chamber
b/w iris and lens
what is aqueous humor
where is it produced
where does it flow
where does it drain and via what
- Refractive fluid filling anterior and posterior chambers.
- Produced in posterior chamber by ciliary processes of ciliary body.
- Flows from posterior chamber to anterior chamber via pupil.
- 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.
- Scleral venous sinus drains to vorticose and anterior ciliary veins.
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.
where is the vitreous body
b/w lens and posterior surface of the eye
filled with vitrous humor–> a transparent refractile jelly-like substance
what is exopthalmos
a. Protrusion of eyeball from orbit.
b. Seen in certain diseases such as hyperthyroidism, orbital tumors.
what is enopthalamos
a. Protrusion of eyeball from orbit.
b. Seen in certain diseases such as hyperthyroidism, orbital tumors.
what is the main artery that supplies the orbit and the eye itself
where does this artery enter the orbit
ophthalmic artery (branch of internal artery)
enters orbit via the optic canal
what does ciliary mean in terms of arteries
going to the eye itself (usually outer layers)
what are the branches off the ophthalmic artery (11)
central retinal artery shorter posterior ciliary long posterior ciliary anterior ciliary lacrima supraorbital posterior ethmoidal anterior ethmoidal medial palpebral supratrochlear dorsal nasal
central retinal artery
- Pierces optic sheath and runs within optic nerve.
2. Supplies inner layers of retina (except rods/cones and pigmented epithelium layers).
short posterior ciliary arteries
pierce sclera near optic nerve to supply choroid.
long posterior ciliary arteries
pierce sclera anteriorly to supply ciliary body/iris.
anterior ciliary arteries
arise from muscular branches; to ciliary body and iris.
lacrimal artery
to lacrimal gland and lateral portions of eyelids
supraorbital artery
to forehead and scalp
medial plpebral a.
medial eyelids
supratrochlear
to forehead and scalp
dorsal nasal
supplies dorsal surface of nose
where does the central retinal vein drain
directly to cavernous sinus
what does the vorticose vein drain
B. Vorticose veins drain the choroid, ciliary body, and iris.
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).
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.
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.
occlusion of the central retinal vein
papilledema (retinal edema)
compression of the optic nerve
blindness
retinal artery occlusion can cause what
blindness due to loss of blood supply to the retina
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 inferiorly
E. 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
what are the 7 extraocular eyes muscles
levator palpebrae superioris medial rectus lateral rectus superior rectus inferior rectus inferior oblique superior oblique
medial rectus origin insertion function innervation testing integrity
- Origin – common tendinous ring
- Insertion – medial surface of eyeball
- Function – adducts eye
- Innervation – CN III
- Testing integrity – eye held in abducted position; loss of adduction.
lateral rectus origin insertion function innervation testing integrity
- Origin – common tendinous ring.
- Insertion – lateral surface of the eyeball
- Function – abducts eye.
- Innervation – CN VI
- Testing integrity – eye held in adducted position; loss of abduction
Superior rectus origin insertion function innervation testing integrity
- Origin – common tendinous ring
- Insertion – superior surface of eyeball
- Function – elevates, adducts; intorsion
- Innervation – CN III
- Testing integrity – weakness of elevation; loss of elevation when eye is fully abducted.
inferior rectus origin insertion function innervation testing integrity
- Origin – common tendinous ring
- Insertion – inferior surface of eyeball
- Function – depresses, adducts; extorsion
- Innervation – CN III
- Testing integrity – weakness of depression; loss of depression when eye is fully abducted.
inferior oblique origin insertion function innervation testing integrity
- Origin – anterior portion of floor of orbit
- Insertion – inferior surface of eyeball, posterior to the equator (vertical axis)
- Function – elevates, abducts; extorsion.
- Innervation – CN III
- Testing integrity – weakness of elevation; loss of elevation when eye is fully adducted.
superior oblique origin insertion function innervation testing integrity
- Origin – common tendinous ring
- Insertion – superior surface of eyeball, posterior to the equator (vertical axis)
- This muscle passes through a trochea and changes its direction to attach to the eyeball.
- Function – depresses, abducts; intorsion.
- Innervation – CN IV
testing ability- weakness of depression; loss of depression when eye is fully adducted
how do we look up?
superior rectus and inferior oblique
how do we look down
superior oblique and inferior rectus
go to eye website from funks lecture
do it
UC Davis?
also see funks slide 59-60
are images depicting functions of EO muscles and how you test the clinically different?
yes
testing lateral rectus clinically
have patient abduct their eye
testing medial rectus clinically
have the patient adduct their eye
testing superior rectus
Superior rectus – have patient abduct their eye and then elevate.
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
how do we test the superior oblique
Superior oblique – have patient adduct their eye and then depress.
how do we test the inferior oblique
Inferior oblique – have patient adduct their eye and then elevate.
what 6 of the CN’s are associated with the orbit
CNII SSA (optic canal)
through superior orbital fissure CN III GSE, GVE-P CN IV GSE CN V1 GSA CN VI GSE
CNVII SVE to orbicularis oculi
LR6SO4R3
Lateral rectus CN VI
Superior oblique CN IV
All the rest CN III
what three nerves are responsible for innervating the EO eye muscles
CN VI
CN IV
CN III
CN III does what muscles
levator palpebrae superioris
medial, superior, inferior rectus
and inferior oblique
CN IV
superior oblique
CN VI
lateral rectus
