Module 1 Orbit And Eye Flashcards
Origin of Levator palpebrae superioris
Elevation of upper eyelid
Innervated by occulomotor nerve
Origin of inferior oblique
Elevation of eyeball (look up)
Lateral rotation of eyeball (look outward)
Innervated by occulomotor nerve
Origin of superior oblique
Depression of eyeball (look down)
Abduction of eyeball (look out)
Medial rotation if eyeball
Innervated by trochlear nerve
Eyeball rotation is limited around the anterior posterior axis
Origin of medial rectus
Addiction of eyeball (looking in)
Innervated by occulomotor nerve
Common tendinous ring is a fibrous band inside the orbit that surrounds the optic canal and part of superior orbital fissure
Origin of inferior rectus
Depression of eyeball (look down)
Addiction of eyeball (look in)
Lateral rotation of eyeball
Innervated by occulomotor nerve
Common tendinous ring
Located on posterior orbit
Fibrous ring that surrounds structures entering orbit through optic canal and medial part of superior orbital fissure
Origin of rectus muscles of eye
Origin of lateral rectus
Abduction of eyeball (looking out)
Innervated by abducens nerve
Origin of superior rectus
Elevation of eyeball (look up)
Adduction of eyeball (look in)
Medial rotation of eyeball
Innervated by occulomotor nerve
Eyeball rotation is limited movement
Orbital surface of the frontal bone
Roof of orbital
Has anterolateral fossa for lacrimal gland
Entire orbital roof formed by frontal bone and lesser wing of the sphenoid bone
Orbital plate of ethmoid bone
Medial wall of the orbit
Thin walled smooth lateral surface of ethmoid bone that forms large part of medial wall of orbit
Covers middle and posterior ethmoidal air cells
Aka lamina papyracea
Sphenoid bone
Unpaired irregular bone of the skull that resembles a butterfly
Contains sella turcica
Orbital surface of maxilla
Orbit floor, smooth bony plate
Forms medial and anterior boundaries of inferior orbital fissure
Floor of orbit susceptible to blow out fracture following anterior blunt force to eye (fist, elbow, baseball)
Fossa for lacrimal sac
Shallow depression that contains lacrimal sac and continues inferiorly with nasolacrimal duct
Lacrimal sac collects tear fluid from lacrimal canaliculi
Superior orbital fissure
Located in posterior region of orbit and middle cranial fossa
Oblique fissure bordered by sphenoid bone and frontal bone
Connects orbit with middle cranial fossa, transmits occulomotor, trochlear, and abducens nerves as well as branches of the opthalmic nerve
Optic canal
Short canal connecting orbit with middle cranial fossa
Transmits optic nerve and opthalmic artery
Eye
Globe like structure composed of three layers (fibrous, vascular, and neural)
Fibrous is cornea and sclera
Vascular is choroid, ciliary body, and iris
Neural is retina and pigment epithelium
Optical components collect and focus light while neural portions process and transmit light driven signals to the brain
Inferior rectus muscle
Depression of eyeball, Adduction of eyeball, lateral rotation of eyeball
Inferior oblique muscle
Elevation of eyeball, lateral rotation of eyeball
Superior rectus muscle
Elevation of eyeball, Adduction of eyeball, medial rotation of eyeball
Eyeball rotation is a limited movement
Medial rectus muscle
Adduction of eyeball
Superior oblique muscle
Depression of eyeball, abduction of eyeball, medial rotation of eyeball
Optic nerve (CN II)
Provides for vision
Connects to lateral Geniculate nucleus of thalamus
Retinal ganglion pathway- optic nerve- optic chiasm- optic tract- brainstem nuclei
Trochlea of superior oblique
Anterior medial wall of orbit
Fibrous loop through which tendon of superior oblique muscle passes
Redirects tendon from medial wall of orbit to superior aspect of eye
Central retinal artery
Passes through optic canal with each optic nerve, pierces optic nerve and courses to retina
Blockage may cause blindness
Optic disk
Where retina meets optic nerve
Circular to oval area composed of optic fibers that form optic nerve
Central retinal artery enters eye through optic disk
Lack of photoreceptors in disk creates blind spot in visual field
Choroid
In vascular layer of eye
Contains dark brown pigment melanin
Gives blood supply to outer part of neural retina and prevents light reflections in the eye
Retina
Inner layer of the eye
Outer pigmented layer immediately inside choroid, inner neural layer contains photoreceptors and associated neurons
Photoreceptors are sensory neurons that respond to light, axons form optic nerve and connect eye to brain
Sclera
Fibrous layer of eye
Outer layer of posterior 5/6 of eye axe of dense collagenous connective tissue
Protects eye and maintains eye shape
“White of the eye”
Posterior cavity of the eye
Posterior to the lens and it’s ligaments
Cavity of eye occupied by vitreous humor
Maintains normal intraoccular pressure and shale of the eye, maintains lens and retina in place, refracts light
Aka vitreous chamber
Orna serrata
Serrated anterior margin of neural portion of retina
Lens
Located posterior to iris
Biconvex lens composed of cells called lens fibers that refracts light and focuses light onto neural retina
Suspensory ligaments of lens
Located between ciliary body and lens
Transparent elastic fibers that suspend the lens from the ciliary body and connects ciliary muscle to lens
Permits thickness of lens to change with contraction and relaxation of ciliary muscle
Contraction of ciliary muscle relaxes ligaments and thickens lens
Relaxation of ciliary muscle tenses ligaments and thins lens
Ciliary body
Vascular layer of eye composed of ciliary muscle and ciliary processes
Angular ciliary smooth muscle controls tension of suspensory ligaments to adjust thickness of lens, ciliary processes produce aqueous humor
Scleral venous sinus
Aka canal of schlemm
Oval cleft that collects aqueous humor from anterior chamber for reabsorption into venous system
Iris
Colored part of eye that regulates pupil size in response to light
Contains pupillary constrictor and dilator muscles
Constrictor is parasympathetic while dilator is sympathetic
Pupil
Opening in the center if the iris that allows light to enter the eye
Size controlled by muscles in the iris
Pupillary sphincter
Closes pupil
Innervated by parasympathetic axons, composed of smooth muscle
Pupillary dilator
Dilates pupil, composed of smooth muscle Innervated by sympathetic axons
Ciliary muscle
Contraction permits lens to thicken for accommodation
Parasympathetic innervation
Anterior cavity
Cavity between cornea and lens filled with aqueous humor, produced in the posterior chamber
Anterior chamber
Subdivision of anterior cavity filled with aqueous humor
Cornea
Transparent connective tissue layer of anterior 1/6 of eye that is the site of light refraction, protects the eye
Posterior chamber
Subdivision of anterior cavity that produces aqueous humor
Optic chiasm
Ventral part of diencephalon between optic nerve and optic tract
White matter tract composed of axons of retinal ganglion from both eyes traveling to thalamus and other brainstem nuclei
Some axons from each retina cross in chiasm to enter opposite optic tract
Optic tract
Between optic chiasm and brainstem nuclei
White matter composed of axons of retinal ganglion cells from both eyes traveling to thalamus
Retinal ganglion goes optic nerve- optic chiasm- optic tract- brainstem nuclei
Infundibulum of pituitary
Contains hypothalamo-hypophysial portal tract and portal vein that carries hormones to the anterior pituitary
Transmits anti-diuretic hormone and oxytocin to posterior pituitary
Occulomotor nerve (CN III)
Motor control of medial, superior, inferior rectus muscles and inferior oblique muscle and levator palpebrae superioris muscle
Parasympathetic innervation to pupillary sphincter and ciliary muscle
Connects to midbrain
Trochlear nerve (CN IV)
Motor control of superior oblique muscles
Connects to midbrain
Abducens nerve (CN VI)
Middle cranial fossa and orbit
Motor control of lateral rectus muscle
Connects to pons
