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SPECIAL SENSES Lori Mathis, CST ST 110 OBJECTIVES Describe the functions and structures of the eyes and adnexa Recognize, define, spell, and pronounce terms related to the pathology, diagnostic and treatment procedures of eye disorders OBJECTIVES CONT. Describe the functions and structures of the ears Recognize, define, spell, and pronounce terms related to the pathology, diagnostic and treatment procedures of ear disorders FUNCTIONS OF THE EYE The eye is a sensory and receptor organ that receives images and transmits them to the brain EYE TERMINOLOGY Optic: pertaining to the eye or sight Ocular: pertaining to the eye Extraocular: outside the eyeball Intraocular: within the eyeball STRUCTURES OF THE EYE Adnexa: (also known as adnexa oculi) includes orbit, eye muscles, eyelids, eyelashes, conjunctiva, and lacrimal apparatus Orbit: (also know as the eye socket) bony cavity of the skull that contains and protects the eyeball and its associated muscles, blood vessels, and nerves EYE MUSCLES Six major muscles attached to each eye Provide for wide range movement Work together in coordinated movements that enable normal binocular vision NOTE: Binocular refers to the use of both eyes working together THE EYELIDS Upper & Lower lids protect the eyeball from - Foreign matter - Excessive light - Impact Canthus: angle where upper and lower eyelids meet Inner canthus: where the eyelids meet nearest the nose EYELIDS CONT. Epicanthus: vertical fold of skin on either side of the nose Tarsus: (also known as the tarsal plate) plate like framework within the upper and lower eyelids that provides stiffness and shape THE EYEBROWS & EYELASHES Prevent foreign matter from reaching the eyes Edges of the eyelids contain cilia (eyelashes) and oil-producing sebaceous glands THE CONJUNCTIVA Mucous membrane that lines the underside of each eyelid and continues to form a protective covering over the exposed surface of the eyeball and oil-producing sebaceous glands THE LACRIMAL APPARATUS (Also known as tear apparatus) consists of structures that produce, store, and remove tears Lacrimal glands: located above the outer corner of each eye. Secrete lacrimal fluid (tears) Lacrimation: normal continuous tear secretion Lacrimal canaliculi: ducts in the inner corner of each eye. Collect tears and drain into lacrimal sac THE LACRIMAL APPARATUS CONT. Lacrimal sac: known as dacryocyst or tear sac. The enlargement of the upper part of the lacrimal duct Lacrimal duct: known as the nasolacrimal duct, Is the passageway that drains lacrimal fluid into the nose THE EYEBALL Also known as the globe. It is a 1-inch sphere with walls made up Of three layers: - Sclera - Choroid - Retina It is also divided into anterior and Posterior segments THE SCLERA The “white of the eye” Outer fibrous tissue layer of the eye Maintains the shape of the eye and protects the delicate inner layers of tissue Cornea: is the transparent anterior portion of the sclera NOTE: The cornea provides most of the optical power of the eye THE UVEAL TRACT Known as the uvea and is the vascular layer of the eye. Includes the: - Choroid - Iris - Ciliary body THE CHOROID Choroid layer or choroid coat The opaque middle layer of the eyeball Contains many blood vessels and provides the blood supply for the entire eye The Iris Pigmented (colored) muscular layer that surrounds the pupil THE PUPIL The black circular opening in the center of the iris that permits light to enter the eye HOW THE PUPIL WORKS Muscles within the iris control the amount of light that is allowed to enter To decrease the amount of light these circular muscles contract and make the opening smaller To increase the amount of light, the muscles dilate (relax) and make the opening larger THE LENS (Also known as the crystalline lens, is a clear, flexible, and curved structure that focuses mages on the retina. It is held in place by the suspensory ligament from the ciliary body. THE CILIARY BODY Located within the choroid Set of muscles and suspensory ligaments that adjust the lens to refine the focus of light rays on the retina To focus on nearby objects, these muscles adjust to make the lens thicker To focus on distant objects, these muscles stretch the lens so it is thinner THE RETINA Sensitive inner nerve layer of the eye located between the posterior chamber and the choroid layer at the back of the eye Contains specialized light-sensitive cells called rods ( black and white receptors) and cones (color receptors) Rods and cones receive images and convert them into nerve impulses THE MACULA LUTEA Clearly defined yellow area in the center of the retina This is the area of sharpest central vision THE FOVEA CENTRALIS The pit in the middle of the macula lutea. Color vision is best because of high concentration of cones THE OPTIC DISC The BLIND SPOT (NO Rods or Cones) Nerve endings of the retina gather to form the optic nerve THE OPTIC NERVE Cranial nerve II (two) Transmits nerve impulses from the retina to the brain ANTERIOR EYE SEGMENT • Front 1/3 of the eye is divided into anterior and posterior chambers -- Anterior chamber: behind the inner surface of the cornea and in front of the iris -- Posterior chamber: located between the back of the iris and the front of the lens ANTERIOR SEGMENT CONT. • Filled with aqueous humor • Fluid nourishes the intraocular structures • through the trabecular meshwork and the • canal of Schlemm • Constant drainage regulates intraocular • pressure NOTE: Humor is any clear body liquid or semifluid substance POSTERIOR EYE SEGMENT • Posterior 2/3 of the eyeball is filled with vitreous humor • This jelly-like mass aids the eye in maintaining its shape • Lined with retina and its related structures NORMAL ACTIONS OF THE EYE Accommodation: process by which the eye makes adjustments for seeing objects at varying distances Convergence: simultaneous inward movement of both eyes (toward each other) usually an effort single binocular vision Emmetropia: normal relationship between the refractive power of the eye and the shape of eye that enables light rays to focus correctly on the retina. Refraction: ability of the lens to bend the light rays to help them focus on the retina Normal eye: Light rays focus on the retina REFRACTIVE DISORDERS Hyperopia: (farsightedness) Light rays focus beyond the retina REFRACTIVE DISORDERS Myopia: (nearsightedness) Light rays focus in front of the retina VISUAL ACUITY Ability to distinguish object details and shape at a distance. Normal vision stated as 20/20 Snellen Chart: used to measure visual acuity First number indicates the distance from the chart which is a standard 20 feet Second number indicates the deviation from the norm based on the ability to read lines of letter on the chart EYELID PATHOLOGY Blepharoptosis: drooping of the upper eyelid Ectropion: eversion (turning outward) of the edge of the eyelid Entropion: inversion (turning inward) on the edge of the eyelid Hordeolum: (stye) an infection of one or more glands at the border of the eyelid Chalazion: localized swelling of the eyelid resulting from sebaceous gland obstruction ADNEXA PATHOLOGY Dacryocystitis: inflammation of the lacrimal sac and is associated with faulty tear drainage Conjunctiva: (pinkeye) inflammation of the conjunctiva Xerophthalmia: (dry eye) drying of eye surfaces characterized by the loss of luster of the cornea and conjunctiva SCLERA, CORNEA, IRIS Scleritis: inflammation of the sclera Snellen Chart: used to measure visual acuity Keratitis: inflammation of the cornea Corneal Abrasion: injury such as a scratch or irritation to the outer layers of the cornea Corneal Ulcer: pitting of the cornea caused by infection or injury Iritis: inflammation of the iris EYE Anisocoria: condition in which the pupils are unequal in size Cataract: loss of transparency of the lens. May be congenital or caused by trauma or disease Papilledema: swelling and inflammation of the optic nerve at the point of entrance through the optic disc Floaters: (vitreous floaters) particles that float in the vitreous fluid and cast shadows on the retina EYE Nystagmus: involuntary, constant rhythmic movement of the eyeball Retinal Detachment: retina is pulled away from it normal position of being attached to the choroid Uveitis: inflammation anywhere in the uveal trac May affect the choroid, iris, or ciliary body GLAUCOMA Characterized by increased intraocular pressure GLAUCOMA Open-angle Glaucoma: most common form. Trabecular meshwork becomes detached. Closed-angle Glaucoma: the opening between the cornea and iris narrows so that fluid can’t reach the trabecular meshwork NOTE: glaucoma does not produce symptoms noticed by the patient until the optic nerve has been damaged. Regular eye exams can detect this before damage occurs MACULAR DEGENERATION Gradually progressive condition that results in th loss of central vision but not in total blindness MACULAR DEGENERATION CONT. Dry-type Degeneration: accounts for 90% of cases. Caused by the atrophy of the macula Wet-type Degeneration: associated with formation of new blood vessels that produce hemorrhages FUNCTIONAL DEFECTS Diplopia: (double vision) Hemianopia: blindness in one half of visual field Monochromatism: color blindness Nyctalopia: night blindness Presbyopia: changes in eyes that occur with aging STRABISMUS Known as a squint Disorder in which eyes cannot be directed in a parallel manner toward the same object Estropia: also known as cross-eyes. Inward deviation of one eye in relation to the other Extropia: also known as wall-eye. Outward deviation of one eye relative to the other REFRACTIVE DISORDERS A condition in which the lens and cornea do not bend light to that it focuses properly on the retina NORMAL VISION REFRACTION DISORDER HYPEROPIA (FARSIGHTEDNESS) REFRACTION DISORDER MYOPIA (NEARSIGHTEDNESS) DISORDERS Ametropia: error of refraction in which only objects located a finite distance from the eye are focused on the retina Astigmatism: eye does not focus properly because of unequal curvatures of the cornea Hyperopia: defect in which light rays focus beyond the retina (farsightedness) Myopia: defect in which light rays focus in front of the retina (nearsightedness) BLINDNESS Amblyopia: dimness of vision or partial loss of sight without detectable disease of the eye Blindness: inability to see. Legally blind is when best-corrected vision is 20/200 Scotoma: abnormal area of absent or depressed vision surrounded by an area of normal vision (blind spot) DIAGNOSTIC PROCEDURES Visual Acuity Measurement: evaluation of the eye’s ability to distinguish object details and shapes Refraction: determine eye’s refractive error and best corrective lenses to be prescribed Tonometry: measures intraocular pressure Dilate: administering paralyzing mydriatic drops that forces the pupil to remain wide open even in the presence of light SPECIALIZED DIAGNOSTIC PROCEDURES Flourescein Staining: used to visualize corneal abrasions IV Flourescein Angiography: (IFA) dye injected into arm and pictures taken as the dye passes through blood vessels in the retina. Detects leaking blood vessels within the eye Visual Field Test: determines losses in peripheral vision TREATMENT PROCEDURES Orbitotomy: surgical incision into the orbit for biopsy, abscess drainage, tumor removal or foreign body removal Tarsectomy: surgical removal of a segment of the tarsal plate of the upper or lower eyelid Tarsorrhaphy: partially or completely suturing together the upper and lower eyelids Conjunctivoplasty: surgical repair of the conjunctiva Keratoplasty: corneal transplant. Replacement of scarred or diseased cornea Iridectomy: surgical removal of part of the iris Radial Keratotomy: used to correct myopia. Partial incisions are made in the cornea causing it to flatten Lensectomy: surgical removal of a cataract clouded lens Intracapsular Cataract Extraction: removal of a cloudy lens including the surrounding capsule Phacoemulsificaton: use of ultrasonic vibration to shatter and break up a cataract; easier removal Intraocular Lens: plastic lens surgically implanted to replace the natural lens Aphakia: absence of the lens of an eye after cataract extraction Pseudophakia: natural lens is replaced with an intraocular lens LASER TREATMENTS Laser Trabeculoplasty: creates an opening that allows fluid to drain properly to prevent pressure buildup in the eye Laser Iridotomy: creates an opening in the iris to allow proper drainage Retinopexy: reattachment of a detached retina Sealing leaking or damaged blood vessels Photorefractive Keratectomy: reshaping top layer of the cornea. (PRK) STRUCTURES OF THE EAR Divided into three separate regions: -- Outer ear -- Middle ear -- Inner ear OUTER EAR Pinna/Auricle: external portion of the ear Catches sound waves and transmits them to the external auditory canal External Auditory Canal: transmits sound waves from the pinna to the middle ear Cerumen/Earwax: protective functions MIDDLE EAR Tympanic Membrane/Eardrum: located between the outer and external portions of the ear When sound waves reach it, the TM transmits the sound by vibrating Mastoid Sinus: hollow air spaces located in the mastoid process. An infection in the middle ear can spread rapidly to these cells AUDITORY OSSICLES Three small bones found in the middle ear Transmits sound waves from the eardrum to the inner ear by vibration Malleus: known as the “hammer” Incus: known as the “anvil” Stapes: known as the “stirrup” EUSTACHIAN TUBES Narrow tubes which lead from the middle ear to the nasopharynx Equalize air pressure in the middle ear with the outside atmosphere Oval Window: located under the base of the stapes; separates the middle ear from the inner ear INNER EAR Contains the sensory receptors for hearing and balance Cochlea: spiral-shaped passage leading from the oval window Cochlear Duct: located within the cochlea. Filled with fluid and vibrates when sound waves strike it INNER EAR CONT. Organ of Corti: located within the cochlea. Is the receptor site that receives these vibrations and relays them to the auditory nerve fibers that transmit them to the auditory center of the cerebral cortex, where they are interpreted and heard Semicircular Canals: located within the inner ear and contain endolymph and hairlike cells. Helps maintain equilibrium INNER EAR CONT. Acoustic Nerves: cranial nerve VII, transmits this information to the brain and the brain sends a message to muscles in all parts of the body to insure that equilibrium is maintained NORMAL EAR ACTIONS Air Conduction: Sound waves enter the ear through the pinna, travel down the auditory canal, and strike the TM between the outer and middle ear. Bone Conduction: Eardrum vibrates, it moves the auditory ossicles and these conduct sound waves through the middle ear Sensorineural Conduction: vibrations reach the inner ear via the oval window. The structures in the inner ear receive the sound and relay them to the brain OUTER EAR PATHOLOGY Impacted Cerumen: accumulation of cerumen that forms a solid mass adhering to the walls of the external auditory canal Otalgia: known as an earache Otitis: any inflammation of the ear Otopyorrhea: flow of pus from the ear Otorrhagia: bleeding from the ear MIDDLE EAR PATHOLOGY Eustachitis: inflammation of the eustachian tube Mastoiditis: inflammation of any part of the process Myringitis: inflammation of the TM Otosclerosis: ankylosis of the bones of the middle ear resulting in a conductive hearing loss OTITIS MEDIA PATHOLOGY Acute Otitis Media: inflammation of middle ear usually associated with upper respiratory tract infection. Most commonly in children Serous Otitis Media: fluid buildup in the middle ear that may follow acute otitis media Otitis Media with Effusion: escape of fluid from blood or lymphatic vessels into the tissues or a cavity Purulent Otitis Media: buildup of puss in the middle ear INNER EAR PATHOLOGY Labryinthitis: inflammation of the labyrinth resulting in vertigo Meniere’s Syndrome: chronic disease of the inner ear characterized by three main symptoms: -- Vertigo, fluctuating hearing loss, tinnitus Tinnitus: ringing, buzzing, or roaring in the ears HEARING LOSS Deafness: complete or partial loss of the ability to hear Conductive Hearing Loss: outer or middle ear does not conduct sound vibrations to the inner ear normally Noise-Induced Loss: result of loss of sensitive hairlike cells of the inner ear Sensorineural Loss: nerve deafness Presbycusis: progressive age related hearing loss TREATMENT PROCEDURES Otoplasty: surgical repair of the pinna Mastoidectomy: surgical removal of mastoid cells Myringectomy: surgical incision of the eardrum Tympanoplasty: surgical correction of a damaged Stapedectomy: surgical removal of the stapes Labyrinthectomy: surgical removal of the labyrinth