The Orbit and Eye Flashcards
Conjunctiva
Palpebral conjunctiva, bulbar conjunctiva, conjunctival sac, fornices
Palpebral conjunctiva
membrane lining inner eyelid
Bulbar conjunctiva
membrane lining surface of eye
conjunctival sac
potential space between the palpebral and bulbar conjunctiva
fornices
conjunctival reflections from eyelid to eye
Eyelid
superior and inferior tarsi, superior tarsal m. , tarsal glands, eyelashes
Superior and inferior tarsi
support eyelid, dense CT
Superior tarsal m.
maintains elevation of upper eyelid, sympathetic innervation
Tarsal glands
with tarsi, produce lipid solution to lubricate corners of eye and form barrier
Eyelashes
prevent objects from entering eye by causing reflexive and spontaneous blinking
tarsal (meibomian) glands
with tarsi, produce lipid solution to lubricate corners of eye and form barrier
Gland of Mll
sweat gland, secrete lipid to reduce evaporation
Gland of zeis (ciliary glands)
sabaceous/oil gland associated with eyelash
Innervation to lacrimal gland
Sensory= lacrimal branch of CN V1
Lacrimal fluid production= parasymppathetic fibers of CN VII
Vasoconstriction= postsynaptic sympathetics from superior cervical ganglion to internal carotid plexus
Orbital axes
diverge at approximately 45
Optical axes
for the 2 eyeballs are parallel; in anatomical position, run directly anteriorly
Levator palpebrae superioris m.
Inn: CN III
A: elevates the upper eyelid
Superior rectus m.
Inn: CN III
Action: elevates, adducts, & medially rotates eye (intorsion)
Inferior rectus m.
Inn: CN III
A: Depresses, adducts, & laterally rotates eye (extorsion)
Lateral rectus
Inn: CN VI
A: abducts eye (away from nose)
Medial rectus
Inn: CN III
A: adduct eye (toward nose)
Superior oblique m.
Inn: CN IV
A: depresses, abducts, & medially rotates eye (intorsion)
Inferior oblique m.
Inn: CN III
A: elevates, abducts, & laterally rotates eye (extorsion)
Nerve Innervation- Opthalmic
CN V1
Supplies the lacrimal gland and conjunctiva (forehead and center portion of nose)
3 divisions (“NFL”):
Nasociliary n., frontal n., lacrimal n.
Nasociliary n.
-Ethmoidal and infratrochlear nn.
-Long ciliary nn. (sensory and sympathetics) to posterior eye
Frontal n.
Supraorbital and supratrochlear nn.
Lacrimal n.
supplies sensory to lacrimal gland
Cavernous Sinus
Contents:
-Internal carotid a.
-Oculomotor n. (CN III)
-Trochlear n. (CN IV)
-Opthalmic n. (CN V1)
-Maxillary n. (CN V2
-Abducens n. (CN VI)
Fiberous layer includes
Sclera and cornea
Sclera
Posterior 5/6
-Attachment point for intrinsic and extra-occular eye mm.
-Covered by bulbar conjnctive
Cornea
Anterior 1/6
-Primary refractory medium of the eyeball- change its shape suring laser eye surgery
-Highly sensitive to touch (CN V1)
-Completely avascular- aqueous humor and lacrimal fluid
Vascular Layer includes
Choroid, Ciliary body, and Iris
Choroid
Pigmented, dark reddish-brown layer between the sclera and retina
-Supplied by ciliary branches of ophthalmic artery
-Vascular supply for photoreceptors (rods and cones) of retina- helps to refocus light
-Causes “red eye” reflection in flash photography
Ciliary Body
Connects choroid to iris and provides attachment for lens
-Ciliary processes- secretes aqueous humor
-Smooth muscle- controls lens thickness/focus- acommodation- parasympathetic from CN III via ciliary ganglion
-Zonular fibers- contain suspensory ligaments for accomodation
Iris
- Pupillary schincter= constricts pupil (limits light)
-Cicularly arranged fibers
-Inn by parasympathetics from CN III via ciliary ganglion - Pupillary dilator= dilates pupil (increases light)
-Radially arranged fibers
-Inn by sympathetics from internal carotid plexus
Retina
Optic:
-Neural- contains light receptive neurons
-Pigmented: absorbs/reduces scattering of light
-Non-visual: anterior continuation of pigmented layers with a layer of supporting cells
Macula
of retina, the fovea centralis is a depression located in the center
-Focus light onto fovea
Optic disc
Blind spot, where retinal ganglia axons leave retina
