Head and Neck, Session 5 Flashcards
what is at the apex of the orbit?
foramen= optic canal
in addition to the optic canal, what permits passage of nerves into the orbit?
superior and inferior orbital fissures
protective mechanisms of front of eye?
lacrimal gland
eyelids
via which 2 muscles does movement of eyelids occur?
orbicularis oculi
levator palpebrae superioris
function of orbit?
affords protection of eyeball and its muscles, nerves, vessels and most of lacrimal apparatus
what forms the fascial sheath of the eyeball?
periosteum (periorbita) lining bones of orbit
where is the periorbita continuous with the periosteal layer of dura mater?
at optic canal and supraorbital fissure
what are the eyelids lined by in the inner surface?
conjunctiva
how are the eyelids strengthened?
tarsal plates- dense bands of CT
how are the eyelids prevented from sticking together when they close?
secretion from tarsal glands contained in tarsal plates, which lubricates edges of eyelids
what does the lacrimal apparatus consist of?
lacrimal glands, lacrimal ducts, lacrimal canaliculi
what is a blowout fracture?
indirect trauma or injury that displaces orbital contents
when does a stye form in the eyelid?
when ducts of ciliary glands become obstructed
facial nerve is damaged, how does this affect eye protection?
protection lost as loss of orbicularis oculi function which allows eyelids to close, so loss of protective blinking
so cornea becomes dry and is left unprotected from dust and other particulate mateial
eyeball irritation causes excessive tear formation
how is attachment of extraocular muscles provided?
by outer protective layer of eyeball, comprising sclera and cornea, which is fibrous
what does middle coat of eyeball comprise?
iris, choroid and ciliary body
what is the inner layer of the eyeball?
retina, consisting of optic and non-visual parts
what does the choroid lie between?
the sclera and the retina
what does the choroid terminate as anteriorly?
ciliary body
what does ciliary body connect?
the choroids with the iris
where is the aq humour that fills the chambers of the eye secreted from?
the ciliary body
where is the anterior chamber of the eyeball located?
between cornea and iris
where is posterior chamber of eyeball located?
between iris and ciliary body and lens
what name is given to the central aperture of the iris?
pupil
how is the lens attached to the ciliary body?
by suspensory ligaments
what does the cavity behind the lens contain?
vitreous humor- supports lens and holds retina in place
what is the area of most acute vision?
the fovea centralis
arterial supply of retina?
central artery of the retina
how would damage to opthalmic division of trigeminal nerve affect the eye?
cornea would be rendered vulnerable to foreign objects
what is opacity of lens known as?
cataracts
2 layers of optic retina?
neural layer- light-receptive
pigmented layer
where does optic nerve enter eyeball?
at optic disc
what is a detached retina?
separated neural and pigmented layers of retina, may occur with blow to the eye
what are the muscles of the orbit?
levator palpebrae superioris
superior, inferior, medial and lateral recti
superior and inferior oblique
all supplied by oculomotor except superior oblique- trochlear, and lateral rectus- abducent