Eye Flashcards
what forms the boundaries of the orbit?
roof: frontal bone
floor: zygoma and maxilla
back: zygoma and sphenoid
lateral wall: zygomatic and frontal
medial wall: ethmoid, lacrima, frontal and maxilla
what are the contents of the orbit?
eyeball
fat and connective tissue (the fat pad pushes the eyeball forwards)
extraocular muscles
blood vessel and nerves
what are the tarsal plates and what do they contain?
dense CT
supports eyelids and contains tarsal galnds
what ligaments support the eyeball?
medial and lateral check ligaments
suspensory ligaments
what is the role of the check ligaments?
restrict medial and lateral recti
what forms the eyelid?
lateral and medial palpebral ligaments superior and inferior tarsus superior and inferior orbital septum lacrimal sac tendon of levator palpebrae superioris
what is the cornea continuous with?
the sclera
where is the blind spot of the eye?
optic disc of retina
what is found in the macula lutea?
fovea
what forms the fibrous outer coat of the eye?
sclera/cornea
what forms the middle vascular coat of the eye?
iris, ciliary body and choroid
what forms the inner coat of the eye?
retina
where is aqueous humor made, where is it found, where does it drain to and what is its role?
made by ciliary body
found anterior to the lens, flows from posterior to anterior chambers
drains to the canal of schlemm (corneo-scleral junction)
helps maintain intra-ocular pressure
where is the vitreous humor found and what is its role?
transparent jelly
posterior to lens in the vitreous body/cavity
supports the retina
what are the intraocular muscles, what shape are they, what is their role and what are they innervated by?
dilator pupillae: radial, increases pupil diameter (dilator), under sympathetic control
sphincter pupillae: circular, decreases diameter (constrictor), under parasympathetic control via CN III
what is the role of the ciliary muscle and what is it innervated by?
intrinsic eye muscle
changes the shape of the lens
innervated by CN III (oculomotor)
what are the 7 extraocular (extrinsic) muscles?
levator palpebrae superioris
superior, inferior, medial and lateral recti
superior and inferior oblique
where is the levator palpebrae superioris?
orbital roof –> upper eyelid
where are the superior, inferior, medial and lateral recti found?
annular ring –> sclera (anterior to equator)
where is the superior oblique found?
lesser wing of sphenoid –> sclera (posterior to equator)
where is the inferior oblique found?
orbital floor –> sclera (posterior to equator)
what is the action of levator palpabrae superioris and what innervates it?
raise upper eyelid
oculomotor (CN III)
what are the actions of superior rectus and what innervates it?
elevation, adduction, intorsion
oculomotor (CN III)
what are the actions of inferior rectus and what innervates it?
depression, abduction and extorsion
oculomotor (CN III)
what is the action of medial rectus and what innervates it?
adduction
oculomotor (CN III)
what is the action of lateral rectus and what innervates it?
abduction
abducent (CN VI)
what are the actions of superior oblique and what innervates it?
intorsion, depression, abduction
trochlear (CN IV)
what are the actions of inferior oblique and what innervates it?
extorsion, elevation, abduction
oculomotor (CN III)
what is the mnemonic to remember the innervations of the extraocular muscles?
LR6SO4
lateral rectus 6, superior oblique 4
all innervated by oculomotor (CN III) except lateral rectus (CN VI - abducent) and superior oblique (CN IV - trochlear)
what arteries supply the eye?
DR MCLESSI D = Dorsal nasal R = (central) Retinal artery M = Muscular C = Ciliary (long and short posterior and anterior) L = Lacrimal E = Ethmoidal (anterior and posterior) S = Supraorbital S = Supratrochlear (frontal) I = Internal palpebral
what veins drain the eye and what does it drain to?
supra- and infra-orbital vorticose angular facial superior and inferior opthalmic drains to facial vein, pterygoid venous plexus and cavernous sinus
what is the function of the lacrimal apparatus and what is it innervated by?
produces tears
secretomotor fibres from facial nerve (CN VII) carried in trigeminal (CN V1)
what nerves innervate the eye and it’s muscles?
oculomotor nerve (CN III - superior and inferior branches) trochlear nerve (CN IV) trigeminal nerve (CN V - zygomatic, lacrimal, frontal, nasociliary, inferior palpebral, infra-orbital nerve) abducent nerve (CN VI)
optic nerve (CN II - vision)
the tendons of what muscles form the common tendinous ring?
levator palpebrae superioris
medial rectus
inferior rectus
lateral rectus
what travels through the common tendinous arch and what travels just outside it?
through: optic nerve, opthalmic artery, superior and inferior division CN III, CN VI and nasocilairy
outside: superior and inferior opthalmic vein, lacrimal nerve (CN V1), frontal nerve and CN IV
all but optic nerve and opthalmic artery pass through the superior orbital fissure to enter the ring
what travels with the optic nerve (CN II)?
opthalmic artery
what is the frontal nerve a branch of and what is its root value?
largest branch of the opthalmic nerve (CN V1)
so is a branch of the first branch of trigeminal
what does CN III supply parasympathetic innervation to?
sphincter pupillae and ciliary muscles
what are the divisions of the opthalmic nerve?
superior (levator palpebrae, rectus superior) inferior division (rectus medilais, rectus inferior, oblique inferior) oblique inferior gives the short root of the ciliary ganglion
