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• 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