Eye Flashcards
What 7 bones make up the bony orbit?
- frontal
- sphenoid (lesser and greater wings)
- ethmoid
- lacrimal
- maxillary
- zygomatic
- palatine
What are the 9 apertures of the bony orbit?
Near apex - 3:
optic canal
superior orbital fissure
inferior orbital fissure
Near base - 3:
rim of the bony orbit
fossa of lacrimal duct
superior orbital foramen
On medial and inferior walls - 3:
infraorbital groove
infraorbital foramen
ant./post. ethmoidal foramina
What passes through the optic canal?
- CN II
2. ophthalmic artery
What passes through the superior orbital fissure?
- CN III, IV, ophthalmic branch of V, VI
2. superior ophthalmic vein
What passes through the inferior orbital fissure?
infraorbital nerve of V2
What transmits the infratrochlear nerve?
rim of bony orbit
What is in the fossa of the lacrimal duct?
lacrimal lake
lacrimal papillae
lacrimal sac
nasolacrimal duct
What passes through the supraorbital foramen?
supraorbital nerve (terminal branch of frontal nerve of V1), artery, and vein
What passes through the infraorbital foramen?
infraorbital nerve (branch of V2), artery, and vein
What passes through the anterior and posterior ethmoidal foramina?
nerves and vessels of the same name
Where are the tarsal plates?
embedded in each eyelid
What attaches to the tarsal plate?
levator palpebrae superioris
Describe the path of a tear.
lacrimal gland across the globe collect in lake drain into punctum through lacrimal canaliculus into lacrimal sac through nasolacrimal duct out into nasal cavity
What are the 3 muscles that move the eyelids?
- orbicularis oculi - orbital part (wink)
- orbicularis oculi - palpebral part (blink)
- levator palpebrae superioris (open)
What innervates orbicularis oculi?
CN VII
What innervates levator palpebrae superioris?
superior division of CN III
What is the function and innervation of the superior tarsal muscle (of Muller)?
smooth muscle arising from levator palpebrae superioris; opens eyes when startled; sympathetic fibers from carotid plexus
What are the 6 extraocular muscles?
4 rectus: superior rectus medial rectus inferior rectus lateral rectus
2 oblique:
superior oblique
inferior oblique
Which extraocular muscles adduct the eye?
medial rectus
inferior rectus
superior rectus
Which extraocular muscles abduct the eye?
lateral rectus
superior oblique
inferior oblique
Which extraocular muscles depress the eye?
inferior rectus
superior oblique
Which extraocular muscles elevate the eye?
superior rectus
inferior oblique
Which extraocular muscles medially rotate the eye?
superior rectus
superior oblique
inferior rectus
Which extraocular muscles laterally rotate the eye?
inferior oblique
Which extraocular muscles are innervated by CN VI?
lateral rectus
Which extraocular muscles are innervated by CN IV?
superior oblique
Which extraocular muscles are innervated by CN III?
all except lateral rectus and superior oblique
Where is the common tendinous ring (annulus of Zinn)?
surrounds the optic canal
What muscles arise from the common tendinous ring?
the 4 rectus extraocular muscles + superior oblique (basically all but inferior oblique)
Describe the function of the ciliary muscle.
Changes shape of lens.
When ciliary muscle contracts, zonular fibers relax and lens thickens.
When ciliary muscle relaxes, zonular fibers tauten and lens thins.
What is the innervation of the ciliary muscle?
parasympathetics of CN III
What produces aqueous humor?
ciliary body
What muscles control the size of the pupil?
sphincter pupillae: contracts to reduce pupil diameter
dilator pupillae: contracts to increase pupil diameter
What is the innervation of the sphincter and dilator pupillae?
sphincter: parasympathetic
dilator: sympathetic
(both of CN III)
How many photoreceptors are in the optic disc?
none - blind spot where CN II exits the eyeball
What is the site of highest acuity vision?
fovea centralis
What are the 3 chambers of the globe?
anterior chamber
posterior chamber
vitreous chamber
What artery supplies blood to the contents of the orbit?
ophthalmic artery, a branch of the internal carotid
What artery supplies the retina?
central artery of the retina
What arteries supply the globe?
anterior and posterior ciliary arteries
What artery supplies the lacrimal gland, conjunctiva, and eyelids?
lacrimal artery
What nerve fibers participate in the corneal reflex?
somatic sensory fibers carry sensation to brain along the long & short ciliary nerves, nasociliary nerve, and ophthalmic nerve
branchial motor efferent fibers from CN VII innervating the orbiculari oculi muscle cause it to contract, closing the eyelid
What nerve fibers participate in the pupillary light reflex?
special sensory sensations are carried by CN II
visceral motor parasympathetic fibers are carried by the inferior division of CN III and the parasympathetic root of the ciliary ganglion; they synapse; post-ganglionic fibers travel along short ciliary nerves into globe to pupillary constrictor muscle, causing the iris to constrict
