Chapter 2: Anatomy and Physioolgy Flashcards
Globe
The eye, without its surrounding structures
Also called Eyeball
Cornea
The clear membrane at the front of the globe that begins the process of focusing the light the eye receives
2/3 of the Diopter power of the eye
Pupil
The opening in the center of the iris that enlarges or dilates (admitting more light) or constricts (admitting less light)
Crystalline Lens
Part of the optical focusing system of the eye, located immediately behind the iris
Vitreous
The clear, jelly-like substance that fills the space behind the lens
Retina
The inner lining of the posterior segment of the eyeball.
Consists of a layer of light-sensitive cells that convert images from the optical system into electrical impulses sent along the optic nerve for transmission to the brain.
Optic Nerve
The nerve that carries electrical impulses to the brain’s visual cortex, where they are integrated to produce the sensation of sight
Axial Length
The length of the eyeball from the front surface of the cornea to the retina, measured from the optical center.
Pachymetry
The measurement of the corneal thickness by use of a Pachymeter
Adnexa
The tissues and structures surrounding the eye
Includes: orbit, extraocular muscles, eyelids and lacrimal apparatus
Orbit
The bony cavity in the skull that houses the globe, EOM’s, blood vessels and nerves
Blowout Fracture
An injury caused by blunt force trauma applied to the eye, creating pressure the fractures of the orbital bones
Extraocular Muscles
The 6 muscles that attach to the outside of the globe and are responsible for its movements
Medial Rectus Muscle
EOM attached to the nasal side of the globe
Functions to move the eye inward (Adduction)
Innervated by Nerve 3 (Oculomotor)
Lateral Rectus Muscle
EOM attached to the temporal side of the globe
Functions to move the eye outward (Abduction)
Innervated by Nerve 6 (Abducen)
Superior Rectus Muscle
Eom attached to the upper side of the globe
Functions to: elevate the globe (Supraduction)
Innervated by: Nerve 3 (Oculomotor)
Inferior Rectus Muscle
EOM attached to the underside of the globe
Functions to move the eye downward (Infraduction)
Innervated by: Nerve 3 (Oculomotor)
Superior Oblique Muscle
EOM attached to upper, outer side of the globe
Functions to rotate down and outward (Incyclotorsion)
Innervated by: Nerve 4 (Trochlear)
Inferior Oblique Muscle
Eom attached to the lower, outer part of the globe
Functions to move the eye up and outward (Excyclotorsion)
Innervated by Nerve 3 (Oculomotor)
Binocular Vision
The blending of separate images seen by each eye into a single image
Fusion
The blending of the brain of the separate image received by the 2 eyes so that a single view is perceived even when the eyes move
Strabismus
A misalignment of the eyes hat may cause vision to be disturbed
Occurs when the EOMs are not work in a coordinated manner
Diplopia
Double vision
Amblyopia
Decreased vision present without apparent abnormalities in the ocular anatomy and uncorrectable by spectacles or contact lenses
Results from visual deprivation in early childhood
Eyelids
The complex, moveable cover of the outer portion of the globe
Consists of: skin, tarsus, delicate muscles, eyelashes, glands, and conjunctiva
Palpebral Fissure
The almond-shaped opening between the upper and lower eyelids
Canthus (Medial and Lateral)
The point where the upper and lower eyelids meet on the Medial and Lateral sides of the globe
Cilia
Eyelashes
Trichiasis
An abnormality of the eyelid that causes eyelashes to turn in the wrong direction and rub against the surface of the cornea
Stye
An infection or inflammation of the Zeis gland located on the eyelid margin in an eyelash follicle
Also called External Hordeolum
Meibomian Glands
Multiple specialized glands in the upper and lower eyelids that secrete the oily portion of the tear film
Chalazion
An acute infection of a meibomian gland in the eyelid
Also called a Chalazion
Blepharitis
Inflammation of the eyelid margin
Conjunctiva
A thin, translucent mucous membrane extending from the outer corneal border over the globe and the inner surface of the eyelids
Tarsus
The dense, plate-like framework within the middle layer of each eyelid that gives the eyelids their firmness and shape
Levator Palpebrae
The muscle attached to the tarsal plate in the middle layer of the upper eyelids that raises the eyelid when it contracts
Ptosis
Drooping of the upper eyelid most commonly caused by the levator muscle’s inability to lift the eyelid to its fullest extent
Ectropion
A condition in which the eyelid margin is everted outward from the globe
Entropion
A condition in which upper or lower eyelid margin is turned inward
Conjunctivitis
An inflammation of the conjunctiva that causes swelling of the small blood vessels, making the eye appear red
Can be: Bacterial, Viral, Allergic
Also called: Pink Eye
Palpebral Conjunctiva
The portion of the conjunctiva that lines the inner eyelids
Bulbar Conjunctiva
The portion of the conjunctiva that covers the globe
Fornix
The loose pocket of conjunctival tissue where the palpebral and bulbar portions of the conjunctiva meet in the recess of the upper and lower eyelids
Subconjunctival Hemorrhage
A rupture of the conjunctival blood vessels that allow blood to flow under the tissue of produces a bright red, flat area on the conjunctiva
Lacrimal Apparatus
The structure for tear production and drainage
Tear Film
The moist coating of the cornea
Composed of 3 layers: aqueous, mucus and oil
Lacrimal Gland
The gland that produces the watery substance making up the middle layer of the tear film
Schirmer Tear Test
A test that uses a strip of filter paper to measure the patient’s tear output and helps confirm the diagnosis of Dry Eye
Phenol Red Thread Test
A test that aids in the diagosis of dry eyes and uses cotton threads treated with a pH indicator to measure the patient’s tear production
Punctum (Upper and Lower)
The tiny opening on the upper and lower eyelid margins near the nose, through which tears pass
Canaliculus (Upper and Lower)
One of 2 small channels that starts at the punctum in the upper and lower eyelids and drains tears from the surface of the eye into the lacrimal sac
Nasolacrimal Duct
The duct through which tears pass from the lacrimal sac into the nasal cavity
Dacryocystitis
Inflammation of lacrimal sac, usually caused by a blockage of the nasolacrimal duct
Anterior Segment
The front of the eye
Includes the structures between the front surface of the cornea and the vitreous
Posterior Segment
The rear portion of the eye
Includes vitreous and retina
Corneal Epithelium
The outermost layer of the cornea
Provides defense against infection and injury
Bowman Membrane
The 2nd layer of the cornea, between the epithelium and the stroma
Corneal Stroma
The 3rd, middle layer of the cornea
Contributes to the rigidity of the cornea
Descemet Membrane
The 4th layer of the cornea
Also contributes to the rigidity of the cornea
Corneal Endothelium
The 5th, innermost layer of the cornea. Composed of a single layer of cells
Helps maintain fluid balance and prevent swelling
Corneal Abrasion
A scratch or defect in the corneal epithelium
Corneal Ulcer
Pathologic condition involving a defect in the corneal surface and associated with inflammation
Infectious ulcers are due to bacteria
Sclera
The outer fibrous tissue of the globe, which surrounds the cornea and forms the wall of the eye
Protects intraocular contents
Limbus
The junction between the sclera and the cornea
Anterior Chamber
The small compartment between the cornea and the iris that is filled with clear fluid called the aqueous humor
Posterior Chamber
The space between the back of the iris and the front of the vitreous, the crystalline lens is suspended in this chamber
Aqueous Humor
The clear, transparent fluid that fills the anterior chamber
Anterior Chamber Angle
The junction between the cornea and the iris, from which aqueous humor leaves the eye
Also called Filtration angle
Canal of Schlemm
A structure that drains the aqueous humor from the anterior chamber after it has flowed through the trabecular meshwork
Aqueous Veins
Fluid from the Canal of Schlemm then drains into the aqueous veins
Uvea
The pigmented layers of the eye (iris, ciliary body, and choroid) that contain the majority of the blood vessel supply
Iris
The colored circle of tissue that controls the amount of light entering the eye by enlarging or reducing the size of its aperture, the pupil
Dilator Muscle
The iris muscle that dilates the pupil in reduced light conditions
Fibers from this muscle stretch from this muscle to the outer boundaries of the iris
Sphincter Muscle
The muscle that encircles the pupil and makes the pupil smaller in response to bright light
Ciliary Body
A band-like structure of muscle and secretory tissue that extends from the edge of the iris and encircles the inside of the sclera
Ciliary Processes
A finger-like extension of the ciliary body that produces aqueous humor
Ciliary Muscle
The muscle fibers in the ciliary body of the uveal tract that are involved in accommodation
Choroid
A layer of tissue largely made up of blood vessels that nourishes the retina. It lies between the sclera and the retina in the uveal tract
Zonules
A transparent fiber that supports the crystalline lens by attaching to the ciliary body.
Assists in the accommodation process
Cortex
A clear paste-like protein that surrounds the nucleus of the crystalline lens
Accommodation
The change in the curvature of the crystalline lens that helps to focus images of objects that are close to the eye
Presbyopia
The progressive loss of accommodation ability of the lens, due to aging
Cataract
An opacified or clouded lens
Opacification
Clouding of a structure, most often seen in the cornea or lens
Floaters
Small particles of dead cells or other debris that become suspended in the vitreous, or particles of the vitreous itself that degenerates in the normal aging process. They cast shadows in the retina and can appear as spots or cobwebs.
An urgent eye visit
Pigment Epithelium
The outer layer of the retina; lies against the choroid
Photoreceptor
A light- sensitive cell
Rods or Cones
Rods
The retinal photoreceptor cell largely responsible for vision in dim light and for peripheral vision
Cones
The retinal photoreceptor cell largely responsible for sharp central vision and for color perception
“Central, clear, color”
Found in Macula
The Optic Disc
The location where the central retinal artery enters and central retinal vein, as well as the nerve fibers, exits
Also called Optic Nerve Head
Macula
The specialized area of the retina close to the center of the back of the eye that provides detailed central vision
Fovea
The center of the macula
Bipolar Cells
A type of retinal cell that accepts electrical impulses from the photo-receptors and passes them to the ganglion cells
Ganglion Cells
The type of retinal cell that accepts electrical impulses from the bipolar cells and sends nerve impulses to axons through the Optic Disc to the brain
Axons
The long fiber-like portion of a ganglion cell that courses over the surface of the retina and converges at the optic disc
Physiological Blind Spot
The sightless “hole” in the normal visual field corresponding to the optic disc, where there are no photoreceptors,
Cup-to-disc Ratio
The comparison of the size of the central cup to the size of the optic nerve
Rim
The tissue surrounding the cup
Optic Atrophy
The death of axons, which compromises the optic nerve and results in a pale optic nerve
Central Nervous System
The eye is considered to be part of the central nervous system
Visual Pathway
The route that is taken by light-generated nerve impulses after they leave the eye
Also called Retrobulbar Visual Pathway
Optic Chiasm
The point behind the eyes in the brain where the 2 optic nerves merge and the axon fibers from the nasal retina of each eye cross to the opposite side of the
Optic Tracts
The part of the brain between the optic chiasm and the lateral geniculate body
Lateral Geniculate Bodies
The part of the brain along the visual pathway where optic fibers synapse to the optic radiations and transmit visual impulses
Synapse
The connection between nerves, where electrical impulses are transmitted
Optic Radiation
The nerve fibers that transmit visual information from the lateral geniculate body to the visual cortex
Visual Cortex
The area of the brain responsible for the initial conscious registration of visual information; the designation of nerve impulses from the retina
