Orbit and Eye Flashcards
How many bones can be found in the orbit?
7 bones
Orbital axes is approximately…
45 degrees
Optical axes (direction/line of sight) is…
parallel
Name six contents of the orbit
- Eye (ball and nerve)
- Extra-ocular muscles
- Lacrimal apparatus
- Periorbital fat and fascia
- Conjunctiva
- Nerves and blood vessels
What are the functions of the eyelids?
- Protect eyeball and cornea
- Spread lacrimal fluid to keep cornea moist
Eyelids are externally covered by ___ and internally lined by ___
covered by skin and internally lined by conjunctiva
What are tarsal (meibomian) glands?
Ciliary glands along eyelashes that secrete lipids to lubricate edges of eyelids
What is a palpebral fissure?
Opening between superior and inferior eyelids
What are palpebral commissures?
Where superior and inferior eyelids meet medially and laterally
Where is the lacrimal gland and what does it secrete?
Located in superolateral part of orbit and secretes lacrimal fluid
Excretory ducts of the lacrimal gland lead to…
lacrimal canaliculi (small canals) near medial angle of eye
What is the lacrimal sac?
Dilated superior part of nasolacrimal duct
The nasolacrimal duct drains into…
inferior nasal meatus
Lacrimal fluid production is stimulated by which cranial nerve’s fibers?
Parasympathetic fibers from CN VII
lacrimal apparatus
Greater petrosal nerve (preganglionic fibers) joins deep petrosal nerve (sympathetic fibers) to form…
the nerve of pterygoid canal (vidian nerve) to pterygopalatine ganglion
lacrimal apparatus
Postganglionic fibers travel from pterygopalatine ganglion on ___ to ___
on zygomatic nerve (branch of V2) to lacrimal nerve (branch of V1)
lacrimal apparatus
Sympathetic fibers travel from ___ to ___ as deep petrosal nerve to nerve of pterygoid canal
superior cervical ganglion to internal carotid plexus
lacrimal apparatus
Sympathetic fibers travel from superior cervical ganglion to internal carotid plexus as ___ to ___
deep petrosal nerve to nerve of pterygoid canal
What are the boundaries of the anterior chamber of anterior segment of the eyeball?
Cornea to iris/pupil
What are the boundaries of the posterior chamber of anterior segment of the eyeball?
Iris/pupil to ciliary body
The anterior segment of the eyeball is filled with…
aqueous humor
What are the boundaries of the posterior segment of the eyeball?
Lens to retina
The posterior segment of the eyeball is filled with…
vitreous humor
The posterior segment of the eyeball is held in place by the…
mesh vitreous body
What are the three layers of the eyeball?
- Fibrous layer (outer coat)
- Vascular layer (middle coat)
- Inner layer (inner coat)
What structures are found in the fibrous layer of the eyeball?
- Sclera
- Cornea
What is the sclera?
- Opaque (white) layer covering posterior 5/6
- Attachment for muscles
What is the cornea?
- Transparent layer covering anterior 1/6
- Completely avascular
What structures are found in the vascular layer of the eyeball?
- Choroid
- Ciliary body
- Iris
Describe choroid
- Dark reddish-brown layer
- Highly vascular
What is ciliary body?
- Ring-like thickening posterior to corneoscleral junction (ora serrata)
- Smooth muscle and vasculature
___ secrete aqueous humor
Ciliary processes (of ciliary body)
What attaches ciliary body to lens?
Suspensory ligaments
What are the two muscles found in the iris?
- Sphincter pupillae
- Dilator pupillae
What is the innervation of sphincter pupillae?
Parasympathetic innervation
What is the innervation of dilator pupillae?
Sympathetic innervation
What layer of the eyeball contains the retina and its structures?
Inner layer
What is the optic disc?
Blind spot of the retina
What is fovea centralis?
Center of macula lutea, densely saturated with cones
What is ora serrata?
Irregular border of macula between retina and ciliary body
What is the innervation of levator palpebrae superioris?
Oculomotor nerve (CN III) and sympathetic fibers
What is the main action of levator palpebrae superioris?
Elevate superior eyelid
What is the innervation of superior oblique?
Trochlear nerve (CN IV)
What are the main actions of superior oblique?
Adducts, depresses, and medially rotates eyeball
What is the innervation of inferior oblique?
Oculomotor nerve (CN III)
What are the main actions of inferior oblique?
Abducts, elevates, and laterally rotates eyeball
What is the innervation of superior rectus?
Oculomotor nerve (CN III)
What are the main actions of superior rectus?
Elevates, adducts, and rotates eyeball medially
What is the innervation of inferior rectus?
Oculomotor nerve (CN III)
What are the main actions of inferior rectus?
Depresses, adducts, and rotates eyeball laterally
What is the innervation of medial rectus?
Oculomotor nerve (CN III)
What is the main action of medial rectus?
Adducts eyeball
What is the innervation of lateral rectus?
Abducent nerve (CN VI)
What is the main action of lateral rectus?
Abducts eyeball
The optic nerve (CN II) exits the skull through…
optic canal
The oculomotor nerve (CN III) exits the skull through…
superior orbital fissure
The superior division of the occulomotor nerve (CN III) innervates which muscles?
Levator palpebrae superioris and superior rectus
The inferior division of the oculomotor nerve (CN III) innervates which muscles?
Medial rectus, inferior rectus, and inferior oblique
Preganglionic parasympathetic fibers to ciliary ganglion are involved in which cranial nerve?
Inferior division of oculomotor nerve (CN III)
The trochlear nerve (CN IV) exits the skull through…
superior orbital fissure
Which muscle does the trochlear nerve (CN IV) innervate?
Superior oblique
Abducent nerve (CN VI) exits the skull through…
superior orbital fissure
What muscle does abducent nerve (CN VI) innervate?
Lateral rectus
Ophthalmic nerve (CN V1) exits the skull through…
superior orbital fissure
The frontal nerve, nasociliary nerve, and lacrimal nerve all come from…
ophthalmic nerve (CN V1)
Where is the ciliary ganglion?
Located between optic nerve and lateral rectus
Short ciliary nerves are sensory branches of…
V1 (nasociliary nerve)
Short ciliary nerves carry what fibers to where?
Postganglionic parasympathetic and postganglionic sympathetic fibers to ciliary body and sphincter pupillae
Which ciliary nerves go through ciliary ganglion?
Short ciliary nerves (long ciliary nerves do not)
Long ciliary nerves are sensory branches of…
V1
Long ciliary nerves carry what fibers to where?
Postganglionic sympathetic fibers to dilator pupillae
What are the main arteries of the orbit?
- Ophthalmic artery
- Infraorbital artery
The ophthalmic artery is a branch of…
internal carotid artery
What are the branches off the ophthalmic artery?
- Central artery of retina
- Lacrimal
The infraorbital artery is a branch of…
maxillary artery
What are the veins of the orbit and what do they drain into?
Superior and inferior ophthalmic veins drain into cavernous sinus
After a resection of a lymphangioma from the apex of her right lung, a patient experiences ptosis and miosis in her right eye
What structure was likely damaged during the surgery?
Sympathetic trunk/chain
Obstruction of what structure prevents tears from draining?
Lacrimal gland