Eye and Orbit Flashcards
what bones make up the margin of the bony orbit?
frontal, maxilla, zygomatic
what bones are in the medial wall of the orbit?
lacrimal, ethmoid, lesser wing of the sphenoid, maxilla
what bones make up the superior walll (roof) of the orbit?
frontal
what bones make up the lateral wall of the orbit?
zygomatic
what bones make up the floor of the orbit?
PALATINE, zyomatic, maxilla
what travels through the optic canal?
optic canal, superior orbital fissure , inferior orbital fissure, anterior and posterior ethmoidal foramina, lacrimal canal, infraorbital groove
what travels through the superior orbital fissure?
with CN II, ophthalmic artery
what travels through the inferior orbital fissure?
ophthalmic, CN III, IV, and superior ophthalmic vein
what travels through the anterior and posterior ethmoidal foramina?
anterior and posterior ethmoid nerves and artery (from nasociliary on V1) to the sphenoid and ethmoid sinuses in the nasal cavity
what travels through the lacrimal canal?
lacrimal duct (connecting the orbit and nasal cavity)
what travels through the infraorbital groove?
passage of infraorbital nerve (v2) and artery from orbit to suborbit aread of face.
what are the medial/ lateral attachments of the orbicularis oculi palpebrae muscles?
medial and lateral palpebral ligaments; the medial palpebral ligament is exposed, and the lateral palpebral ligament is behind the orbicularis oculi palpebrae muscle
what is the function of the tarsal plates of the orbit?
collagenous plates that maintain the shape of the eyelids
what is the orbital septum?
a thin collagenous sheath that holds up the tarsal plates
what holds the tarsal plates in position?
the palpebral ligament; attaches to the maxilla (medially) and zygomatic (laterally)
what is the palpebral fissure?
the opening made by the upper and lower eyelids
what is unique about the superior tarsus compared to the inferior one?
the superior one is directly attached to the levator palpebrae suprioris muscle
what are the attachments of teh orbicularis oculi muscle?
palpebral part: attached to the tarsal plate
orbital: attached to the orbital septum and rim of the bony orbit
what nerve innervates the orbicularis oculi muscle?
Facial (VII).. temporal branch to upper eyelid, zygomatic to lower eyelid
what muscle is responsible for elevation of the upper eyelid?
levator palpebrae superioris (III) + superior tarsal muscle (postganglionic SYMPATHETIC)
what nerve innervates the levator palpebrae superioris?
occulomtor (III): superior branch
what does the superior tarsal muscle do? what it is innervated by?
assists the LPS to elevate the upper eyelid; has postganglionic sympathetics
what is conjunctiva? what does it come from? what are its divisions (where is each division located)?
= a thin, moist mucous layer of epithelium that comes from skin covering the external portion of the lids transitioning
Divisions: palpebral = attached to lids
bulbar = attached to the eye bulb
what are the superior and inferior conjunctival fornices developed from?
the transition of palpebral to bulbar conjunctiva creating a pocket under the upper and lower lids
where does the bulbar conjunctiva attach to the eye bulb?
cornea-sclera junction
what types of glands are associated with the eye?
sweat, lacrimal, Tarsal/Meibomian
How are sweat glands associated with the eye?
in the lashes and skin
what are tarsal/meibomian glands?
modified sebaceous glands that are embedded in the superior and inferior tarsal plates
what do meibomian glands appear as in the eye?
striations in the palpebral conjunctiva in each lid
what is the function of meibomian glands?
produce surfactant; a protein which spreads our water (doesn’t allow it to aggregate) so as to keep the cornea/eye moist so it doesn’t dry out; works with serous glands
where is the lacrimal gland located?
just below the SUPERIOR orbital rim, along its lateral margin
what divides the lacrimal gland?
tendon of LPS
where do the lacrimal ducts empty out into?
the lateral portion of the superior conjunctival fornix
how does the lacrimal gland receive innervation?
preganglionic axons travel down the greater petrosal nerve (VII) and join the deep petrosal nerve (T1) as the nerve to pterygoid, travels through the pterygoid canal, and then synapses on the pterygopalatine ganglion; then the postganglionic axons travel with the zygomatic nerve (V2) through the zygomaticotemporal branch to the lacrimal nerve (V1) to stimulate aqueous tear formation to keep the conjunctiva and cornea hydrated and clear from debris
what is the function of the lacrimal apparatus?
aspirating off tears from the surface of the eye and depositing them into the nasal cavity via nasolacrimal duct. It includes the nasolacrimal duct and lacrimal sac
where is the lacrimal sac located?
in the lacrimal fossa
what is the nasolacrimal duct’s function
empties contents from the sac into the nasal cavity through the nasolacrimal canal
what are the lacrimal canaliculi?
ducts that lead to the lacrimal sac
whatis the larimal caruncle
a raised structure that is covered by bulbar conjunctiva; resides between the two lacrimal canaliculi
what is periorbital? what is it continuous with?
its the periosteum of the orbit; its continuous with the periosteal layer of the dura ;
what does the periorbital give rise to?
gives rise to the orbital septum, optic nerve sheath (dura mater) and common tendinous ring
does the eye have dural meninges? if so, what layers?
yes! it has pia + arachnoid + optic sheath (dura mater)
What is Tenon’s capsule? does it surround the entire eye? what muscles does it invest?
a cuplike sheath that surrounds the posterior half of the eyeball. It forms a potential space between it and the eyeball which allows the eye to move freely; invests the 6 extrinsic muscles of the eye (4 rectus + 2 obliques) LPS IS NOT ENCASED BY TENON’S CAPSULE and the optic nerve
what are the medial and lateral check ligaments attach?
the sclera to the Tenon’s capsule (fascial sheath)
what are the suspensory ligaments in the orbit?
a thickening of the tenon’s capsule that forms a cradle-like structure beneath the eye and that aids in suspending the eye in the orbit
what is the clinical significance of tenon’s capsule?
if someone has to have their eye removed (ie: optic nerve is cut/way damaged) then the tenon’s capsule maintains the eye socket so that a glass eye can be placed in there and the muscles will articulate it and the glass eye will move because the muscles are not innervated by CN II. IT KEEPS THE MUSCLES OF THE ORBIT INTACT
what is the function of retrobulbar fat? where is it found?
found in the posterior orbit (external to the fascia sheath) and it aids in forming the cup-like socket that serves to cushion and accommodate eye fluid eye movement
is LPS an extrinsic eye muscle? why/why not?
No; it is not involved in actual eye movement (even though it is innervated by III): it is only responsible for elevation of the UPPER EYELID
what muscles originate at the common tendinous ring?
all 4 rectus eye muscles
what does the CTR enclose?
the optic canal and part of the superior orbital fissure (and their contents)
where do the superior/inferior oblique muscles originate from
NOT CTR. from the orbit bones
Where does the LPS originate from?
NOT CTR. from the orbit bones
describe the superior obliques position in the eye
forms a 150 degree bend around its medial cartilaginous attachment (trochlea) and then reflects posteriorly to attach to the posterior/lateral portion of the eyeball (superior)
describe the inferior oblique’s position in the eye
origin at the medial florr of the orbit (posterior to the rim of the orbit and it attaches to the posterior/lateral aspect of the inferior surface of the bubl (eyeball)
where is the center of axis of the orbit?
25 degrees LATERAL of the mid-sagittal plane
how do the obliques function in relation to their respective rectus muscles?
the obliques allow for counter rotation that happens from the rectus muscles to keep the eyes level
what does the superior branch of the CN III innervate?
LPS, SR,
what does the inferior branch of the CN III innervate?
MR, IR, IO
what goes through the common tendinous ring?
"OO SINA" O:optic nerve O: ophthalmic ARTERY S: superior branch of oculomotor I: inferior branch of oculomotor N: nasocliliary of V1 A: abducent
(Note: OO’s go through the optic canal to the CTR, the SINA go through the superior orbital fissure which runs on the lateral side diagnoal of the CTR)
what nerves are superior to the CTR? what do they run through?
run through superior orbital fissure; "F The Larynx Sucks" F: frontal nerve (V1) T: Trochlear nerver (4) L: lacrimal nerve (V1) S: superior opthalmic VEIN
what is unique to the optic nerve (coverings) that is not present on any other cranial nerves?
invested by pia, arachnoid, and encased by dural sac (continuous with the meninges of the cranial cavity); thus the optic nerve up to the base of the eye is bathing in CSF
what does the ophthalmic nerve (V1) divide into before it enters the orbit via superior orbital fissure?
- lacrmial (superior to CTR)
- nasocilary (through CTR)
- frontal nerve (superior to CTR)
what branches off of the frontal nerve? what CN does the frontal nerve come from? what muscle is located near? what it’s relation to that muscle?
Frontal nerve = a branch of V1
it branches into: supratrochlear and supraorbital nerves
located superior to the LPS (it runs superior to the CTR)
what are the branches of the nasoclililary nerve? what CN does it come from?
Nasociliary = off of CN V1
Branches into anterior and posterior ethmoidal nerves, long ciliary nerves, cililary ganglion, infratrochlear nerve
what is the function of the nasociliary nerve?
sensory to the roof of the nasal cavity
what is the function of the long ciliary nerves? what nerve do they branch from?
come from the nasociliary branch (V1): function in SYMP nerve innervation to the posterior eye
what is the function of the infratrochlear nerve? what nerve does it branch from?
it is the terminal branch of the nasociliary nerve (V1); functions in sensory to the bridge of the nose (inferior to the trochlea) and adjoins the orbital region
what is the course of the lacrimal nerve?
a branch of v1 (branches before entering the superior orbital foramen); it enters the superior orbital foramen and runs SUPERIOR to the CTR. It then travels on the superior surface of LR and provides SENSORY to the region.
Also it has parasymp innevation via the greater petrosal nerve (VII) which joins the zygomatic nerve after it synapses in the PT ganglion and then travels witth the larcrimal nerve to increase lacrimation
where is the ciliary ganglion located?
adjacent to the superior/lateral surface of the optic nerve sheath
how is the ciliary ganglion involved in parasymp innervation?
it received preganglionic parasymp fibers from the inferior branch of III, and then gives rise to short ciliary nerves which penetrate the sclera of the bulb (eyeball) SUPERIOR to the optic nerve
what is the function of the short ciliary nerves?
they provide post gang parasymp fibers (from III) and sensory fibers of V1 o the eye
what muscles are innervated by the parasymp innervation from ciliary ganglion?
ciliary muscle (involved in accomodation.. changing of the lens shape so that you can see up close); and sphinctor pupillae muscle (closing of the pupil in response to increasing intensity of light)
where do sympathetics of the eye arise from?
long ciliary nerves of nasalciliary nerve mainly + some from short ciliary
does the ciliary ganglion come off of inferior or superior III?
INFERIOR III
what supplies sensory to the upper eyelid?
V1 = lacrimal supraorbital suprtrochlear and infratrochlear nerves
what supplies sensory to the lower eyelid
v2 via infraorbital nerve branch
what intrinsic muscles of the eye are innervated by parasymps? symps?
sphinctor pupillae (constriction)+ ciliary muscle = parasymp; dilator pupillae
function of sphinctor pupillae vs. dilator pupillae (and response to light)
sphinctor = constriction due to light dilator = dilation due to dimming of light
what is the function of the ciliary muscle? describe what happens when the muscle is contracted vs. relaxed
change the shape of the lens by putting/ releasing tension on the lens via zonular fibers;
Relaxed = pull on the lens (tension) = lens flattens = see far
contracted = no tension on the lens = lens more rounded = see close
what are the branches of the ophthalmic artery (from the internal carotid)? and the ophthalmic artery pathway
first branch of internal carotid artery; enters through the optic canal (INFERIOR TO OPTIC NERVE) and passes through the CTR where it gives rise to the CENTRAL RETINAL ART.; once its in the orbit, it branches into:
- LACRIMAL
- SHORT CILIARY
- SUPRAORBITAL
- ANTERIOR + POSTERIOR ETHMOIDAL
- SUPRATROCHLEAR
what artery anastomoses with the ophthalmic artery? where?
facial artery via angular artery; in the orbit; to supply the eyelids
where is the central retinal artery located? what is it a branch of? what is its function? what is it’s clinical significance?
branch of the ophthalmic artery; it runs straight THROUGH the optic nerve;IT IS THE ONLY SUPPLY OF OXYGEN TO THE RETINA; if it is lesioned then the retina is no longer supplied with blood, it dies, and thus the optic nerve no longer is functioning (blind)
what is the relation of the optic nerve to the ophthalmic artery?
the opthalmic artery is inferior to the optic nerve in the optic canal
what is located inferior to the CTR?
inferior ophthalmic vein
what is the course of the ophthalmic veins?
anastamos with the infraorbital veins, angular veins of facial vein, in communication with the pterygoid plexus, pass superior/inferior to the CTR (respectively) and then both drain into the cavernous sinus.
what is the clinical significance of the opthalmic veins?
they communicate with the pterygoid plexus, angular vein (facial), and infraorbital vein (MID B PIGS maxillary ) and then drain into the cavernous sinus.. prone to spreading of infection from the face to cranium
what happens to the appearance of the optic disk if intracranial pressure is increased? why?
normal = concave (innie)
increased intra cranial pressure = convex (outie)
because the increased cranial pressure causes the optic disk to be displaced into the vitreal chamber of the eye
How does bell’s palsy affect the eye?
CN VII lesion; causes dropping of lower eyelid and loss of tone in upper eyelid due to paralysis of orbicularis oculi
** LOWER LID DOES NOT CLOSE BUT THE UPPER EYELID DOES BECAUSE STILL GET CN III INNERVATION!!!! (to LPS) and still get sympathetic input to the superior tarsal muscles
Excessive tearing occurs due to inability of the lacrimal part of the orbicularis oculi contracting against the lacrimal sac .. therefore can aspirate the tears and their release into the nasal cavity via nasolacrimal duct
Why/how do black eyes (shiners) occur?
due to thin layer of CT around the orbital part of the eye and skin’s loose attachment to the orbicularis oculi muscles, an accumulation of blood resulting from a neighboring injury pools there and displays discoloration and swelling
Which cranial nerves are tested in an eye exam? How? Any ANS? how?
II: Can you see me?
III: upper eyelid blinking (LPS), extrinsic muscles SR, MR, IR, IO
IV: SO?
V: V1 = sensory to upper eyelid + cornea/blink reflex when touched
V2 = sensory to the lower eyelid
VI: LR
VII: Facial muscles of expression (orbicularis oculi).. can you SQUEEZE your eyes shut?
VIII: auditory/vestibular
Lacrimation = PS via III Accomodation = PS via III Pupil contstriction = PS via III Pupil dilation = SYMP via SCG some eyelid movement = SYMP via superior tarsal muscle
