the orbits and contents (eye) (A20) Flashcards
protection of our eyeballs
- bony orbits
- eyelids
- tears
- sensory nerve supply and the blink reflex (very relevant to dentists as eyes are within the operative field of the dentist)
components that help us to ‘see’
- anatomy of the eye (optic nerves)
- extraocular muscles (how we move our eyes)
extraocular muscles
muscles involved in movement of eyes
bones of the orbit
- roof of orbit (orbital plate of the frontal bone containing anterior and posterior ethmoidal foramen)
- apex (at optic canal through sphenoid bone medial to lesser wing of sphenoid bone and superior to tiny section of palatine bone)
- lateral wall of the orbit (greater wing of sphenoid, lateral to superior orbital fissure and lesser wing of sphenoid and superior to inferior orbital fissure)
- floor of the orbit (maxilla bone- containing infraorbital canal which joins to infraorbital foramen)
- medial wall of orbit (ethmoid bone, lateral to lacrimal bone and lacrimal fossa)
- base (called the orbital rim) -> made up of frontal bone with supraorbital notch/foramen, maxillary bone with infraorbital foramen and canal, and zygomatic bone with zygomaticofacial foramen)
2 divisions of orbicularis oculi
- orbicularis oculi = muscle of facial expression
- 1.orbital part (surrounds the eyelids, used to screw up eyes)
2. palpebral part (within the eyelids, used in blinking)
components of eyelids (underneath palpebral part of orbicularis oculi)
- tendon of levator palpebrae superioris (contains skeletal and smooth muscle and attaches superior part of superior tarsal plate)
- superior tarsal plate/inferior tarsal plate (elongated plates of dense connective tissue found in each eyelid,upper and lower, and contribute to its form and support/make up palpebral part of orbicularis oculi)
- medial palpebral ligament (attaches to frontal process of maxilla and lacrimal bone) and lateral palpebral ligaments (the band that attaches the tarsal plates to the orbital eminence of the zygomatic bone)
- palpebral fissure (space between the open eyelids)
- orbital septum (fascia covering posterior aspect of orbicularis oculi)
conjunctiva
the mucous membrane that covers the front of the eye and lines the inside of the eyelids
tarsal gland
special kind of sebaceous gland at the rim of the eyelids inside the tarsal plate, responsible for the supply of meibum, an oily substance that prevents evaporation of the eye’s tear film
-tendon of levator palpebrae superioris
contains skeletal and smooth muscle and attaches to superior part of superior tarsal plate
-superior tarsal plate/inferior tarsal plate
elongated plates of dense connective tissue found in each eyelid,upper and lower, and contribute to its form and support/make up palpebral part of orbicularis oculi
medial palpebral ligament
attaches to frontal process of maxilla and lacrimal bone
palpebral fissure
space between the open eyelids
orbital septum
fascia covering posterior aspect of orbicularis oculi
lateral palpebral ligaments
the band that attaches the tarsal plates to the orbital eminence of the zygomatic bone
sagittal section of eyelid (from deep to superficial)
palpebral conjunctiva -> tarsal glands -> superior tarsal plate (with levator palpebrae superioris attaching superiorly) -> palpebral orbicularis oculi ->skin
cornea
the transparent layer forming the front of the eye/translucent layer covering the iris
vessel visible from medial aspect of eye when looking up and pulling down on lower eye lid
conjunctival vessel (conjunctivitis)
are of conjunctiva at medial canthus
lacrimal lake (the small cisternlike area of the conjunctiva at the medial angle of the eye, in which the tears collect after bathing the anterior surface of the eyeball and the conjunctival sac)
medial canthus
inner corner of the eye, where the upper and lower lids meet
lateral canthus
the outer corner of the eye, where the upper and lower lids meet
opening to lacrimal duct/canaliculi
inferior and superior lacrimal punctum/puncta (one per eye lid) (swelling around this = inferior lacrimal papilla)
conjunctival fornix
the space formed by the junction of the bulbar and palpebral portions of the conjunctiva, that of the upper lid = the superior conjunctival fornix and that of the lower lid = the inferior conjunctival fornix
different types of conjunctiva
- palpebral conjunctiva (lining eyelids)
- scleral (bulbar) conjunctiva lining the sclera
sclera
the tough, white outer coat of the eyeball
location of lacrimal gland
in the upper lateral part of the orbit
function of lacrimal gland
produces tears (supplied by autonomic nervous system)
superior and inferior lacrimal canaliculi
- small canals
- also known as lacrimal ducts, these tube-like structures carry the tears from the eyes to the lacrimal sac
- openings to these = superior and inferior lacrimal punctum