Sense Organs: The ye & the Ear

THE EAR   Combining Forms for the ear: ot/o, aur/o, auricul/o   Two functions of the ear: Hearing Equilibrium (balance)   Three separate regions of the ear: Outer ear Middle ear Inner ear

1.Auricle (pinna) – projecting flap where sound waves enter 2.Auditory canal leads from pinna to middle ear 3.Produces cerumen (ear wax) which lubricates and protects the ear OUTER EAR Auricle Auditory canal

Sound waves travel through auditory canal and strike membrane between outer & middle ear. This membrane is called the tympanic membrane or eardrum. The tympanic membrane vibrates with sound waves and moves 3 small bones in the middle ear. These small bones are called ossicles. MIDDLE EAR Tympanic Membrane

The three small bones also have individual names: 1.Malleus – the TM moves this bone first 2.Incus – vibration moves this bone next 3.Stapes (staped/o) – vibrates last and touches the next membrane called the oval window MIDDLE EAR Tympanic Membrane Malleus Incus Stapes

Oval window Oval window separates the middle ear from the inner ear. Eustachian Tube Eustachian Tube (salping/o) leads from the middle ear to pharynx Is normally closed, except when swallowing. Aids in prevention of damage to eardrum and shock to middle and inner ear when air pressure is greater in the middle ear than in atmospheric air. MIDDLE EAR Tympanic Membrane Malleus Incus Stapes Oval Window Eustachian Tube

Also called the labyrinth because of it’s circular, maze-like structure. Cochlea (cochle/o) leads from the oval window; small, snail shaped; has two parts: 1.Auditory Liquids a. Perilymph b. Endolymph c. Vibrations travel through these liquids 2.Organ of Corti – sensitive auditory receptor; are tiny hair like calls that receive vibrations from auditory liquids and relay sound waves to auditory nerve fibers. INNER EAR Cochlea

Auditory Nerve Fibers – receive sound vibrations from the auditory liquids and end in the auditory center of the cerebral cortex of the brain where impulses are heard and interpreted. Vestibule – connects the cochlea to 3 semicircular canals for balance. Semicircular canals (Organ for Equilibrium) – contain endolymph & hair cells that fluctuate in response to movement of the head; nerve fibers send message to brain & brain sends message to muscles to maintain balance. “-saccule” & “–utricle” are membranous sacs INNER EAR Cochlea Auditory Nerve Fibers Vestibule Semicircular Canals

Figure Pattern of events in the stimulation of a sense organ. SEQUENCE OF EVENTS IN STIMULATION OF SENSE ORGAN

Figure Pathway of sound vibrations from the outer ear to the brain (cerebral cortex). PATHWAY OF SOUND VIBRATIONS

1.Conduction – caused by impairment of the middle ear ossicles and membranes that transmit sound waves into cochlea. 2.Nerve – caused by impairment of the cochlea or auditory nerve TYPES OF DEAFNESS

Figure Ear thermometer using a tympanic membrane thermometer. AURAL TEMPERATURE

HEARING acous/o = HEARING acoustic = SENSE OF HEARING audi/o = SENSE OF HEARING audiometer = HEARING audit/o = HEARING auditory = HEARING -cusis = HEARING presbycusis = EAR CONDITION LARGE EARS -otia = EAR CONDITION macrotia = LARGE EARS SMALL EARS microtia = SMALL EARS ABBREVIATIONS RIGHT EAR AD = RIGHT EAR LEFT EAR AS = LEFT EAR BOTH EARS AU = BOTH EARS EAR, NOSE, & THROAT ENT = EAR, NOSE, & THROAT EYES, EARS, NOSE, & THROAT EENT = EYES, EARS, NOSE, & THROAT COMBINING FORMS & ABBREVIATIONS

1. Otitis Media – inflammation of middle ear, caused by infection (staphylococcus or streptococcus bacteria) 2. Tinnitus – tinkling sound in the ear; can be ringing, buzzing, whistling, etc…. 3. Vertigo – sensation of irregular or whirling motion of oneself or external objects; equilibrium and balance are affected. PATHOLOGICAL CONDTIONS

(A) (A) Healthy tympanic membrane. (B) (B) Tympanic membrane with cholesteatoma. (C) (C) Tympanic membrane with acute otitis media. (D) (D) Myringotomy with tympanostomy tube. TYMPANIC MEMBRANE

4. Meniere’s Disease – disorder of labyrinth marked by elevated endolymph pressure. Symptoms include tinnitus, vertigo, and loss of hearing. Cause is unknown. Bedrest, sedation and drugs for nausea and vertigo are commonly given. 5. Otosclerosis – bone growth around oval window and stapes leading to fixation (stiffening) causing improper conduction of vibration. Corrected with stapedectomy and replacement by prosthesis. PATHOLOGICAL CONDTIONS

(A) (A)Stapedectomy. Using microsurgical technique and a laser, the stapes bone is removed from the middle ear. (B) (B)A prosthetic device (wire, Teflon, or metal) is placed into the incus and attached to a hole in the oval window. TREATMENT FOR A FORM OF CONDUCTION HEARING LOSS

Otomycosis - ot/o = __ myc/ = __ osis = Myringotomy - myring/o = ___ tomy = Myringitis - myring/o = __ itis = __ Otopyorrhea - ot/o = __ py/o = __ rrhea = Ossiculoplasty - ossicul/o = ___ plasty = DEFINE THESE PATHOLOGICAL CONDITIONS

Audio / gram – Audio / meter – Audio / metry – Oto / scopy – EAR PROCEDURES

Figure Pure- tone audiometer.AUDIOMETER

Figure Otoscopic examination. The auricle is pulled up and back. The hand holding the otoscope is braced against the face for stabilization. OTOSCOPIC EXAM

Chapter 17 The Chapter 17 (Cont’d) The

Cor/o and Pupil/o = pupil Pupil - the dark center of the eye Conjunctiv/o – conjunctiva Conjunctiva – clear membrane that lines inner surface of eyelids & over whites of eyes. Corne/o and kerat/o = cornea Cornea – a fibrous, transparent tissue that extends over the pupil of the eye and iris. Helps with refraction of light. STRUCTURES OF THE EYE Pupil Conjunctiva Cornea

Scler/o – sclera Sclera – white part of the eye. Avascular – no blood vessels. Choroid – dark brown membrane inside sclera. STRUCTURES OF THE EYE Sclera Choroid

Ir/o – iris Iris – colored portion of the eye. Is also a muscle that surrounds pupil of the eye. If light is bright, the iris gets bigger (contracts) & pupil gets smaller (constricts). If light is dim, the iris relaxes & pupil dilates (gets larger). Mi/o – smaller, less Miosis: constriction of the pupil Mydr/o – wider, enlarge Mydriasis: enlargement of pupil STRUCTURES OF THE EYE Iris Ciliary Body

Cycl/o – ciliary body Ciliary body – a muscle located next to the lens and that two functions: 1. Thickens & thins the lens for refraction (bending of light rays) 2. Secretes aqueous humor (AH) Aqueous Humor – fluid that maintains shape of anterior portion of eye & provides nourishment to structures in the same area. STRUCTURES OF THE EYE Ciliary Body

Phak/o and phac/o – lens of the eye Lens – flat for distant vision and rounded for close vision. Also helps with refraction of light. ACCOMODATION Refractive power of lens is ACCOMODATION STRUCTURES OF THE EYE Lens

Anterior Chamber of Eye: Contains aqueous humor Secreted by ciliary body Maintains shape of anterior eye Constantly produced - leaves eye thru canal that carries it to bloodstream STRUCTURES OF THE EYE Anterior Chamber

Vitreous Chamber of Eye: Contains vitreous humor Maintains shape of posterior eye Refracts light rays Is NOT constantly being produced Loss of VH may mean loss of eye STRUCTURES OF THE EYE Vitreous Chamber

Retin/o - retina Retina – thin, nerve layer that contains rods and cones. Rods are for reduced lighting and peripheral vision. Cones are for color and central vision. STRUCTURES OF THE EYE Retina

When light energy hits rods & cones (in retina) causes chemical changes, that initiate nerve impulse to travel to brain via the optic nerve Optic disc is area where optic nerve meets retina (it has no light receptors – so called blind spot) STRUCTURES OF THE EYE Optic Nerve Optic Disc Macula Fovea Centralis

Macula is small area to the side of the optic disc Macula contains the Fovea Centralis: location of sharpest vision within eye (composed largely of cones) STRUCTURES OF THE EYE Optic Nerve Optic Disc Macula Fovea Centralis

Figure The posterior, inner part (fundus) of the eye, showing the retina as seen through an ophthalmoscope.RETINA

Optic Nerve Fiber – carry light stimulus through nerve fibers to the brain. As fibers enter brain, travel more medially & eventually cross. Optic Chiasm – area where optic nerve fibers cross Nerve fibers from right 1/2 of each retina form an optic tract & synapse in thalamus. Fibers end in the right visual field of the cerebral cortex. Same thing happens with the left half of each retina Images fuse, giving 3 dimensional image: called Binocular Vision BINOCULAR VISION

Figure Pathway of light rays from the cornea of the eye to the cerebral cortex of the brain. PATHWAY OF LIGHT

Thalamus – nerve fibers from right half of each retina form an optic tract and synapse in the thalamus. Fibers will end in the right visual field of the cerebral cortex. Same thing happens with nerve fibers on the left half of each retina. Cerebral Cortex – surface of cerebrum where nerve cells lie in sheets. Receive visual stimulus from thalamus from both sides of the eye. Visual area of cerebral cortex is in occipital lobe of the brain. AREAS OF BRAIN INVOLVED IN VISION

Accommodation – normal adjustment of the eye for seeing objects at various distances – eye has more problems with this as ages Astigmatism – defective curvature of the cornea or lens of the eye. Presby/opia – impaired vision of the cornea or lens of the eye, associated with aging. Hyper/opia – farsightedness (can’t see close objects), rays of light focus behind retina My/opia – nearsightedness (can’t see far away objects), rays of light focus in front of the retina VISIONAL DISTURBANCES

(A)Astigmatism and its correction. (B)Hyperopia and its correction. (C)Myopia and its correction. Dashed lines in B and C indicate the contour and size of the normal eye. ERRORS OF REFRACTION Astigmatism – defective curvature of the cornea or lens of the eye. Presby/opia – impaired vision of the cornea or lens of the eye, associated with aging. Hyper/opia – farsightedness (can’t see close objects), rays of light focus behind retina My/opia – nearsightedness (can’t see far away objects), rays of light focus in front of the retina

DULL, DIM Ambly/o = DULL, DIM Amblyopia = DOUBLE Dipl/o = DOUBLE Diplopia = NIGHT Nyct/o = NIGHT Nyctalopia = LIGHT Phot/o = LIGHT Photophobia = VISION -opsia = VISION Hemianopsia = EYELID Blephar/o = EYELID Blepharoptosis = TEAR DUCTS Dacry/o = TEAR DUCTS TEARS Lacrim/o = TEARS Lacrimal ducts = COMBINING FORMS

Lacrimal (tear) gland and ducts. LACRIMAL TEAR DUCTS

RIGHT EYE OD – RIGHT EYE LEFT EYE OS – LEFT EYE BOTH EYES OU – BOTH EYES VISUAL FIELD VF – VISUAL FIELD AQUEOUS HUMOR AH – AQUEOUS HUMOR VITREOUS HUMOR VH – VITREOUS HUMOR INTRAOCULAR PRESSURE IOP – INTRAOCULAR PRESSUREABBREVIATIONS

Figure (A) Acute bacterial conjunctivitis. Notice the discharge of pus characteristic of this highly contagious infection of the conjunctiva. (B) Anisocoria. DISORDERS OF THE EYE

Cataract. The lens appears cloudy.

DISORDERS OF THE EYE Figure Chalazion.

Figure Glaucoma and circulation of aqueous humor. Circulation is impaired in glaucoma, so that aqueous fluid builds up in the anterior chamber. DISORDERS OF THE EYE

Figure (A) Picture as seen with normal vision. (B) The same picture as it would appear to someone with macular degeneration. DISORDERS OF THE EYE

A normal fluorescein angiogram.PROCEDURES

Figure Ophthalmoscopy. In addition to examining the cornea, lens, and vitreous humor for opacities (cloudiness), the examiner can see the blood vessels at the back of the eye (fundus) and note degenerative changes in the retina.PROCEDURES

Figure Slit lamp examination measuring intraocular pressure by tonometry.PROCEDURES

(A) The Snellen chart assesses visual acuity. (B) Visual fields are examined by comparing the patient's field of vision with that of the examiner's (assuming the examiner's is normal).PROCEDURES

Keratoplasty – surgical repair of the cornea (corneal transplant) Vitrectomy – removal of vitreous humor SURGICAL TREATMENTS

Figure Clinical appearance of the eye after keratoplasty. (Courtesy of Ophthalmic Photography at the University of Michigan, WK Kellogg Eye Center, Ann Arbor, MI. From Black JM, Hawks JH, Keene AM: Medical-Surgical Nursing: Clinical Management for Positive Outcomes, 6th ed. Philadelphia, WB Saunders, 2001, p )

Figure Phacoemulsification of a cataractous lens through a small, self- sealing, scleral-tunnel incision. (From Lewis SM, Heitkemper MM, Dirksen SR: Medical-Surgical Nursing: Assessment and Management of Clinical Problems, 5th ed. Mosby, St. Louis, 2000, p. 454.)

Figure (A) Detached retina. (B) Scleral buckling procedure to repair retinal detachment. (From Ignatavicius DD, Workman ML: Medical-Surgical Nursing: Critical Thinking for Collaborative Care, 4th ed. Philadelphia, WB Saunders, 2002, p )