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 int he 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