A20 - Orbit and the Eye Flashcards
What is at the apex of the orbit?
optic foramen
What makes up the base of the bony orbit?
the orbital rim - this protect the eye
What bones make up the roof of the orbit?
orbital part of frontal bone
sphenoid
What bone contributes to the floor of the wall?
orbital surface of maxilla
zygomatic
palatine bone
(roof of maxillary sinus and inferior orbital fissure)
What bone does the medial wall of the orbit contain?
maxilla lacrimal ethmoid sphenoid (anterior & posterior ethmoidal foramen, lacrimal groove)
What wall is made up of the zygomatic bone and the greater wing of the sphenoid?
lateral wall of the orbit
What part of orbicularis oculi surrounds the eye and causes the eyelids to be shut tightly?
the palpebral part
What is the function of the orbital part of orbicularis oris?
-within the eyelids and is for blinking
What is the function of eyelids?
they cover the eyeball anteriorly protecting against excess light and injury
Where does the tendon of levator papebrae superioris attach and what is its nerve supply?
attach - superior tarsal plate
supply- motor from CN III
What is the function of the medial and lateral palpebral ligaments? and where are the located?
anchor the tarsal plates at the inner and outer corner of the eye
What are the dense bands of connective tissue that make up the eyelid?
tarsal plates (superior and inferior)
What is the role of the tarsal plates?
they are rigid and give the eyelids their shape
What is imbedded in the tarsal plates that provide lubrication to the eyelids preventing them from sticking together?
Tarsal glands
What is anchored to the face via the lateral palpebral ligament and spans to the margin of the orbit?
orbital septum
What is the opening in the eyes?
palpebral fissure
What is the palpebral conjunctiva?
the membrane which covers the internal surface of the eye but is reflected onto the eyes and is continuous with the bulbar conjunctiva
What is the transparent layer covering the sclera?
bulbar conjunctiva
What is the different between bulbar and palpebral conjunctiva?
bulbar - covers the front of the eyelids and contains blood vessels
palpebral - covers the internal surface of the eyelids
What is the conjunctival fornix?
the resting position in the transmission between the two forms of conjunctiva
What is the function of pilca semilunas?
small folds in the bulbar conjunctiva on the inner corner of the eye that allows movement
What is the lateral corner of the eye?
lateral canthus
What is the lacrimal caruncle?
- small reddish body at the medial corner of the eye
- contains modified sebaceous and sweat glands
What is the raised area upon the entrance to the lacrimal puncta?
lacrimal papilla
Where does the lacrimal puncta drain to?
the lacrimal lake
Where is the lacrimal sac located?
in the lacrimal fossa of lacrimal bone
Describe the production and drainage of tears.
- tears are produced by the lacrimal gland via parasympathetic supply
- they was across the eyes and are drained into the lacrimal lake via the lacrimal puncta
- the tears then pass through the lacrimal canaliculi into the lacrimal sac
- the tears are then drained via the nasocrimal duct and exit via the inferior meatus in the cavity
Describe the surface anatomy of the eyeball - pupil, iris, slcera
pupil - black circular opening in the eye which controls the light let into the eye
iris - the coloured part of the eye which contains 2 muscles, sphincter pupillae which contracts the pupil and dilator pupililie which dilates the pupil
sclera - opaque/ white protective part of the eye
What three components make up the vascular layer of the eye?
choroid
iris
ciliary body
What is the ciliary body?
- made up of smooth muscles and blood vessels which connects the choroid to the iris to complete the vascular layer
What produces aqueous humor?
ciliary body
What is the fibrous layer of the eye considered to be?
connective tissue which covers the cornea and the sclera
What makes up the sensory-neuro layer of the eye?
retina
What is the optic disc?
this is where the optic nerve joins with the retina and this creates a blind spot
What is located near the center of the retina?
macula
What is the highly concentrated cone area?
foeva centralis
What is the humor that suppose the retina and the lens which cannot be replaced?
Vitreous humor
What is the structure and function of aqueous humor?
liquid which fills anterior and posterior chambers of the eye which supplies the non-vascular components of the eye
Where is aqueous humor drained to in the eye?
canal of schelmm
what is the build up of undrained aquous humor in the eye?
glaucoma
What are the 6 (7) extra-ocular muscles?
4 rectus muscles
2 oblique muscles
leavator palpebral superioris
What do the rectus muscles (and superior oblique muscle) arise from
common tendinous ring
What is the only muscle that does not arise from the common tendinous ring? and where does it aris?
inferior oblique
arises from the floor
What nerve supplies lateral rectus?
CN VI
What nerve supplies superior oblique?
CN IV
What does CN III supply?
Medial, Inferior , Superior Rectus
Inferior Oblique
Levator palpebrae superioris (+ symapthetic)
What muscles are being tested when the eyeball is full abducted?
inferior oblique
medial rectus
superior oblique
What muscles are being tested when the eyeball is full adducted?
superior rectus
lateral rectus
inferior rectus
Where does venous blood from the eyes drain?
ophthalmic branch of the facial nerve → cavernous sinus
What are the branches of the ophthalmic branch of the internal carotid?
anterior and posterior ethmoidal
supratrochlear
supraorbital
lacrimal
What artery of the eye is an end artery?
central artery of retina
Define end artery?
an artery in with insufficient anastomoses to maintain viability of tissue of occlusion occurs
Map out the ophthalmic nerve division
ophthalmic → frontal → supraorbital
ophthalmic → frontal → supratrochlear
ophthalmic → lacrimal
ophthalmic → nasociliary → posterior ethmoidal
ophthalmic → nasociliary → infratrochlear
ophthalmic → nasociliary → anterior ethmoidal → external nasal
What is the upper eyelid supplied by?
Va
What is the lower eyelid supplies by?
Vb
What is the afferent limb of the blink reflex?
CN Va
What is the efferent limb of the blink reflex?
CN III to orbiculairs oculi
