Chapter 14

Ocular System Eye: structure for sight Extraocular: outside the eye Intraocular: inside the eye Periocular: around the eye

Ocular Accessories (Adnexa/Stroma) Orbit: bony cavity of skull, eye held here Eye muscles: work together for Binocular 7 major muscles per eye 2 oblique, 4 rectus, retractor bulbi 6 Extrinsic muscles provide attachment Eyelids, Canthus (angle where eyelids meet), Tarsal plate (upper n lower eyelids), Meibomian glands, eyelashes, conjuctiva (mucous membrane that lines under side of each eyelid), Lacrimal apparatus (produce/store/ remove tears)

Eyeball / Globe Sclera: fibrous outer layer of eye (white of the eye) Anterior portion = cornea Choroid: opaque middle layer of the eye (not light passage) Pupil : Central circular opening Lens: clear flexible curved capsule located behind the iris and pupil, Adjusts (accommodates) to see near/far Ciliary Body: thickened extension of choroid to aid in accommodation Iris: “Colored portion”, contains muscles that contract pupil in response to light

Eye Contin: Retina: nerve tissue layer that receives images

Canine Eye

Vision Accommodation: Distance Refraction: Lens bends rays of light to help focus Convergence: simultaneous inward movement in both eyes, normally happens as an object moves closer Acuity: sharpness of vision

Common Tests: Eyes PLR: pupillary light reflex: animal’s response to light Flourescein: dye on the surface to detect corneal injury Menace Response: eye should close as object moves towards it Palpebral reflex: blink in response to eye being touched Schirmer tear test: graded paper slip measures tear production

Common Ailments: Anisocoria: unequal pupil size Blepharitis: inflammation of eyelid Blepharoptosis: dropping of eyelid Cataract: cloudiness of eye Entropin: inturning of eyelid Strabismus: “cross eyed”

Common Procedures: Eyes Common prefixes Oplasty: surgical repair Ectomy: removal Otomy: incision Centesis: removal of liquid (to relieve pressure)

EARS: Structures Outer Ear Middle Ear Pinna: external portion that catches sounds waves Middle Ear Eardrum: tissue separating external from middle ear Auditory ossicles: ear bones Malleus, incus, stapes Eustachin tubes Oval window: separates middle from inner ear Round window: membrane receives sound waves Tympanic bulla: located at base of skull

EAR Structures Continued: Inner Ear Bony Labrinth Vestibule: balance and position Semicircular canals: hairlike structures help with spacial awareness Cochlear: recieves and transmits sound waves to the brain

Testing Ears Otoscopy: exam for parasites Otoscope: Tool used for otoscopy

Pathology Otalgia: ear pain Deafness: hearing loss Otomycosis: fungal infection of the ear Otopyorrhea: pus discharge from ear

Activities Diagram of Eye (pg 292) and Ear (pg 299) Outline of Sight (pg 291-292) and Sound (pg 300) Explain balance, and how the body reacts to changes