Download Chapter 11

Chapter 11
Special Senses:
Eyes and Ears
Related Combining Forms
Structure
Related Combining Forms
Eyes
opt/I, opt/o, optic/o,
ophthalm/o
Iris
ir/i, ir/o, irid/o, irit/o
Lens
phac/o, phak/o
Retina
retin/o
Lacrimal apparatus
dacryocyst/o, lacrim/o
Ears
acous/o, acoust/o, audi/o,
audit/o, ot/o
Outer ear
pinn/i
Middle ear
myring/o, tympan/o
Inner ear
labyrinth/o
Functions of Eyes
• Receptor organs of sight
• Receive images and transmit them to the
brain
Structures of the Eyes
• Eyeball
• Adnexa
Structures of Eyes
Adnexa of Eyes
• Structures outside the eyeball
– Orbit
– Eye muscles
– Eyelids
– Eyelashes
– Conjunctiva
– Lacrimal apparatus
Orbit
• Bony cavity of skull that contains and protects
the eyeball and associated muscles, blood
vessels, and nerves
Muscles of Eye
Muscles of Eye
• Six major eye muscles (three pairs)
– Superior and inferior oblique muscles
– Superior and inferior rectus muscles
– Lateral and medial rectus muscles
• Allow for wide range of precise eye
movements
Muscles of Eye
• Binocular vision
– Coordination of eye muscles allowing for
depth perception
• (bin-: two; ocul: eye)
• Depth perception
– Ability to see things in three dimensions
Eyelids, Eyebrows, and Eyelashes
• Provide protection from foreign matter,
excessive light, and injuries
• Canthus
– Angle where upper and lower eyelids meet
• (canth: corner of the eye)
• Cilia
– Small hair making up eyebrows/eyelashes
Eyelids, Eyebrows, and Eyelashes
• Tarsus
– Framework within upper and lower eyelids
providing necessary stiffness and shape
• (tars: edge of eyelid)
Conjunctiva
Conjunctiva
• Transparent mucous membrane lining
underside of the eyelid protecting the
exposed surface of the eyeball
Lacrimal Apparatus
• Structures producing, storing, and removing
tears
• Lacrimal glands
– Located on underside of upper eyelid just
above outer corner of each eye
• Lacrimal fluid
– Maintains moisture on the anterior surface of
eyeball
Lacrimal Apparatus
• Lacrimal canal
– Ducts at the inner corner of each eye
– Ducts collect tears emptying them into
lacrimal sacs
• Lacrimal sac
– Enlargement of the upper portion of the
lacrimal duct
• Lacrimal duct
– Passageway draining excess tears into nose
Eyeball
• One-inch sphere with only about 1/6th of its
surface visible
• Ocular
– Pertaining to the eye
• Extraocular
– Outside the eyeball
• Intraocular
– Within the eyeball
Walls of Eyeball
Walls of Eyeball
• Three layers
– Sclera
• White of the eye
• Maintains shape of eye
• Protects delicate inner layers of tissue
– Choroid
• Opaque middle layer of eyeball
• Provides blood supply to the entire eye
Walls of Eyeball
• Three layers
– Retina
• Innermost layer lining posterior segment of the eye
• Receives nerve impulses and transmits them to
the brain via optic nerve
Anterior Segment of Eyeball
Anterior Segment of Eyeball
• Anterior segment
– Front one-third of eyeball
– Located behind the cornea and in front of the
iris
– Aqueous humor helps maintain shape and
nourishes intraocular structures
– Intraocular pressure measures fluid pressure
inside the eye which is regulated by rate at
which aqueous humor enters/leaves the eye
Posterior Segment of Eyeball
• Posterior segment
– Remaining two-thirds of the eyeball
– Located behind the iris and in front of the
ligaments holding the lens in place
– Lined with the retina
– Filled with vitreous humor
– Fibers attached to the surface of retina help
maintain the shape of the eye
Structures of Retina
• Rods and cones
– Receive images that have passed through
lens
– Images convert into nerve impulses and
transmit to brain via optic nerve
– Rods
• Black and white receptors
– Cones
• Color receptors
Structures of Retina
• Macula
– Light-sensitive area in the center of the retina
– Responsible for sharp central vision
• Fovea centralis
– Pit in the middle of the macula
– High concentration of cones allows for the
best color vision
Structures of Retina
• Optic disk
– Where nerve endings of the retina enter optic
nerve
– Blind spot
– Contains no rods or cones
• Optic nerve
– Transmits nerve impulses from retina to the
brain
Uvea
• Pigmented layer of eye
• Rich blood supply
• Consists of choroid, ciliary body, and iris
Ciliary Body
• Set of muscles and suspensory ligaments
that adjust thickness of the lens and refine
the focus of light rays on retina
• Produces aqueous humor
• To focus on nearby objects, muscles adjust
the lens to make it thicker
• To focus on distant objects, muscles stretch
lens to make it thinner
Iris
• Colorful circular structure surrounding the
pupil
• Muscles control the amount of light entering
through the pupil
• Muscles contract allowing smaller opening to
decrease the amount of light entering eye
• Muscles relax allowing larger opening to
increase the amount of light entering eye
Cornea, Pupil, and Lens
• Cornea
– Transparent outer surface of eye covering iris
and pupil
– Focuses light rays entering the eye
• Pupil
– Black circular opening in the center of the iris
permitting light to enter the eye
Cornea, Pupil and Lens
• Lens
– Clear, flexible, curved structure contained
within clear capsule located behind the iris
and pupil
– Focuses images on the retina
Normal Action of Eyes
• Accommodation
– Eye adjustment for the vision at varying
distances
• Convergence
– Simultaneous inward movement of eyes
toward each other
– Allows maintenance of single binocular vision
as object comes nearer
Normal Action of Eyes
• Emmetropia
– Normal vision
• (emmetr: proper measure)
• Refraction
– Bending of light rays to focus on the retina
• Visual acuity
– Ability to distinguish object details and shape
at a distance
Medical Specialties Related to Eyes
• Ophthalmologist
– Specializes in diagnosing/treating
diseases/disorders of eyes
• (ophthalm: eye)
• Optometrist
– Provides diagnosis of eye diseases,
measuring accuracy of vision determining
need for corrective lenses
• (opt/o: vision)
Medical Specialties Related to Eyes
• Optician
– Health care practitioner who designs, fits, and
dispenses lenses for vision correction
Pathology of Eyes and Vision: Eyelids
• Ptosis
– Drooping of upper eyelid
• Chalazion
– Nodule or cyst related to obstruction in
sebaceous gland
• Blepharitis
– Swelling of eyelid, near eyelash follicles
• (blephar: eyelid)
Pathology of Eyes and Vision: Eyelids
Pathology of Eyes and Vision: Eyelids
• Ectropion
– Turning outward (eversion) of the edge of the
eyelid
• Entropion
– Turning inward (inversion) of the edge of the
eyelid
• Hordeolum
– Pus-filled lesion on the eyelid due to acute
infection in sebaceous gland
Pathology of Eyes and Vision: Eyelids
• Periorbital edema
– Swelling of tissue surrounding the eye(s)
• (peri-: around; orbit: eyeball)
– Associated with allergic reaction
Additional Adnexa Pathology
• Conjunctivitis
– Inflammation of conjunctiva usually due to
infection or allergy
– Pinkeye
• Dacryoadenitis
– Inflammation of lacrimal gland due to
bacterial, viral, or fungal infection
• (dacry/o: tear)
Additional Adnexa Pathology
• Subconjunctival hemorrhage
– Bleeding between conjunctiva and sclera
– Usually due to injury
• Xerophthalmia
– Dry eye due to decreased production of tears
by tear glands
– May be related to aging, systemic diseases or
Vitamin A deficiency
• (xer: dry)
Uvea, Cornea, Iris, and Sclera
• Uveitis
– Inflammation of uvea
• (uve: uvea)
• Iritis
– Form of uveitis affecting structures in the front
of the eye
• Corneal abrasion
– Injury to outer layers of cornea
• (corne: cornea)
Uvea, Cornea, Iris, and Sclera
• Corneal ulcer
– Pitting of cornea due to infection or injury
• Diabetic retinopathy
– Damage to retina as complication of
uncontrolled diabetes
Uvea, Cornea, Iris, and Sclera
• Keratitis
– Inflammation of cornea
– May be bacterial, viral, or fungal
• (kerat: cornea)
• Keratoconus
– Irregular, cone-shaped cornea leading to
distortion of vision
Uvea, Cornea, Iris, and Sclera
• Scleritis
– Inflammation of sclera
– May be associated with infections, chemical
injuries, or autoimmune diseases
• (scler: white of the eye)
Eye
• Anisocoria
– Unequal size of pupils
– May be congenital, or related to head injury,
aneurysm, or pathology of CNS
• (anis/o: unequal; cor: pupil)
• Cataract
– Loss of transparency of lens causing
progressive loss of visual clarity
Eye
• Floaters
– Particles of cellular debris in vitreous humor
casting shadows on the retina
– Occur normally
– May be an indication of retinal detachment
• Photopsia
– Appearance of flashes of light
• (phot: light; -opsia: view of)
Eye
• Miosis
– Contraction of pupil in response to light
– May be due to prescription or illegal drugs
• (mio: smaller)
• Mydriasis
– Dilation of pupil
– May be due to diseases, trauma, or drugs
• (midrias: dilation of pupil)
Eye
• Nystagmus
– Involuntary, constant, rhythmic movement of
eyeball
– Congenital, or due to neurological injury or
drug use
• Papilledema
– Swelling and inflammation of the optic nerve at
the point of entrance into eye through optic disk
• (papill: nipplelike)
Eye
Eye
• Retinal detachment
– Separation of some or all of the retina from
the choroid
– Lack of treatment leads to blindness
• Retinitis pigmentosa
– Progressive degeneration of retina affecting
night and peripheral vision
– Appears as dark pigmented spots on retina
Glaucoma
• Group of diseases characterized by
increased intraocular pressure resulting in
damage to the retinal nerve fibers and optic
nerve
• Open-angle glaucoma
– More common form
– Detected through regular eye examinations
– Asymptomatic until optic nerve is damaged
Glaucoma
• Closed-angle glaucoma
– Narrowing of area between cornea and iris
resulting in decreased fluid to trabecular
meshwork
– Sudden pain, nausea, redness of eye, and
blurred vision
– Lack of treatment leads to blindness in as little
as 2 days
Macular Degeneration
• Progressive condition causing damage to the
macula
• Results in the loss of central vision
– (macul: spot)
• Types:
– Age-related macular degeneration
– Dry macular degeneration
– Wet macular degeneration
Functional Defects
• Diplopia
– Perception of two images of a single object
• Hemianopia
– Blindness in one-half of the visual field
• (hemi-: half)
• Monochromatism
– Inability to distinguish certain colors
• (mon/o: one; chromat: color)
Functional Defects
• Nyctalopia
– Difficulty seeing at night, although normal
daytime vision
• (nyctal: night)
• Photophobia
– Excessive sensitivity to light
• (phot/o: light)
Functional Defects
• Presbyopia
– Decline of near vision related to aging
• (presby: old age)
Strabismus
• Improper eye alignment due to the inability of
eye muscles to coordinate
• Esotropia
– Inward deviation of one or both eyes
• (eso-: inward; trop: turn)
• Exotropia
– Outward deviation of one eye or both eyes
• (exo: outward)
Refractive Disorders
• Ametropia
– Images do not focus properly on retina
– Includes astigmatism, hyperopia, and myopia
• (ametr: out of proportion)
• Astigmatism
– Lack of focus due to uneven curvature of
cornea
Refractive Disorders
• Hyperopia
– Light rays focus beyond the retina
– Farsightedness
• Myopia
– Light rays focus in front of the retina
– Nearsightedness
Blindness
• Inability to see
• Legal blindness
– Best-corrected vision of 20/200
• Amblyopia
– Dimness of vision without any detectable
disease of eyes
• (ambly: dim or dull)
Blindness
• Scotoma
– Abnormal area of diminished vision
surrounded by area of normal vision
Diagnostic Procedures for Vision and Eyes
• Snellen chart
– Measures visual acuity
– Recorded as fraction with 20/20 representing
normal vision
• First number: standard distance from the chart
• Second number: deviation from the norm
• Refraction
– Determines refractive error
– Determines corrective lens prescription
Diagnostic Procedures for Vision and Eyes
• Diopter
– Unit of measurement of the lens' refractive
power
• Cover test
– Determines how eyes work together
– Assesses binocular vision
• Visual field testing
– Determines loss in peripheral vision
Diagnostic Procedures for Eyes
• Ophthalmoscopy
– Use of ophthalmoscope to visually examine
fundus of the eye
• Dilation
– Artificial enlargement of pupil to examine the
interior of the eyes
• Mydriatic drugs
– Force eyes to remain dilated in the presence
of bright light
Diagnostic Procedures for Eyes
• Slit-lamp ophthalmoscopy
– Focusing the beam of light onto parts of the eye
to permit examination of structures at front of
the eye such as the cornea, iris, and lens
• Fluorescein staining
– Application of fluorescent dye to the surface of
the eye via eye drops
– Causes corneal abrasion to appear bright green
Diagnostic Procedures of Eyes
• Fluorescein angiography
– Radiographic study of blood vessels in the
retina after injecting fluorescein dye
• PERRLA (Pupils are Equal, Round,
Responsive to Light and Accommodation)
– Diagnostic observation
– Abnormality could indicate head injury or
damage to the brain
Diagnostic Procedures of Eyes
• Tonometry
– Measurement of intraocular pressure
– Abnormally high pressure may indicate
glaucoma
• (ton/o: tension)
Treatment Procedures of Eyes and Vision
• Orbit and Eyelids
– Orbitotomy
• Surgical incision into orbit for biopsy, abscess
drainage, or removal of tumor/foreign object
– Tarsorrhaphy
• Partial or complete suturing together of upper and
lower eyelids when lids are paralyzed and unable
to close normally
– (tars/o: eyelid)
Treatment Procedures of Eyes and Vision
• Conjunctiva and Eyeball
– Corneal transplant
• Surgical replacement of scarred/diseased cornea
with clear corneal tissue from donor
– Enucleation
• Removal of eyeball, leaving the eye muscles intact
– (e-: out of; nucle: nucleus; -ation: action)
– Ocular prosthesis
• Artificial eye fitting over or replacing malformed
eye
Treatment Procedures of Eyes and Vision
• Conjunctiva and Eyeball
– Iridectomy
• Surgical removal of a portion of the iris
– (irid: iris)
– Radial keratotomy
• Surgical treatment of myopia to bring focal point
closer to retina improving distance vision
Treatment Procedures of Eyes and Vision
• Conjunctiva and Eyeball
– Scleral buckle
• Repairing of detached retina
– Vitrectomy
• Removal of vitreous humor and replacing with
clear solution
Cataract Surgery
• Lensectomy
– Surgical removal of cataract-clouded lens
• Phacoemulsification
– Ultrasonic vibration to shatter and remove
lens clouded by cataract
• Intraocular lens
– Surgically implanted replacement of natural
lens
Corrective Lenses
• Correct refractive errors
– Concave lenses
• Curved inward
• Used for myopia
– Convex lenses
• Curved outward
• Used for hyperopia
• May have two refractive powers (bifocal) or
three refractive powers (trifocal)
Corrective Lenses
• Contact lenses
– Float on tear film in front of eye
– Rigid gas-permeable lenses cover central part
of the cornea
– Disposable soft lenses cover entire cornea
Laser Treatments of Eyes
• Laser iridotomy
– Focused light beam is used to create a hole in
the iris
– Treatment of closed-angle glaucoma
• Laser trabeculoplasty
– Creates opening in the trabecular meshwork
allowing proper drainage of fluid
Laser Treatments of Eyes
• LASIK (Laser-Assisted In Situ
Keratomileusis)
– Treats vision conditions caused by the shape
of cornea
• (-mileusis: carving)
• Photocoagulation
– Use of laser to treat some forms of wet
macular degeneration or to repair small retinal
tears
Laser Treatments of Eyes
• Retinopexy
– Reattaches retinal detachment
Functions of Ear
• Receptor organ of hearing
• Receives sound impulses and transmit them
to the brain
• Inner ear helps maintain balance
• Auditory
– Pertaining to sense of hearing
• Acoustic
– Pertaining to sound or hearing
Structures of Ear
Structures of Ear
• Three separate regions
– Outer ear
– Middle ear
– Inner ear
Outer Ear
• Pinna
– Also known as auricle
– External portion of the ear
– Captures sound waves and transmits them
into external auditory canal
• External auditory canal
– Transmits sound waves to tympanic
membrane of the middle ear
Outer Ear
• Cerumen
– Earwax
– Secreted by ceruminous glands lining auditory
canal
– Protective substance that traps small insects,
dust, debris, and bacteria
Middle Ear
• Transmits sound across space between outer
ear and inner ear
• Tympanic
– Eardrum
– Located between outer and middle ear
– Membrane transmits sound by vibrating
• (Myring/o and tympan/o: tympanic membrane)
Middle Ear
• Mastoid process
– Temporal bone containing hollow air space
surrounding the middle ear
• Auditory Ossicles
– Transmit sound waves from eardrum to inner
ear by vibration
– Malleus (hammer)
– Incus (anvil)
– Stapes (stirrup)
Middle Ear
• Eustachian Tubes
– Lead from middle ear to nasal cavity and
throat
– Equalize air pressure within the middle ear
with that of the outside atmosphere
Inner Ear
• Contains sensory receptors for hearing and
balance
• Structures present in the inner ear are known
as labyrinth
• Oval window
– Located under the base of stapes
– Membrane separating the middle ear from the
inner ear
– Allows entrance of vibrations into inner ear
Inner Ear
• Cochlea
– Snail-shaped structure where sound
vibrations are converted into nerve impulses
– Contains cochlear duct, organ of Corti,
semicircular canals, and acoustic nerves
• Organ of Corti
– Relays vibrations to auditory nerve fibers that
transmit sound to the auditory center of the
cerebral cortex for interpretation
Inner Ear
• Semicircular canals
– Three
– Contain endolymph and sensitive hair cells
the bend in response to the movements of
head
– Assist with equilibrium
Inner Ear
• Acoustic nerves
– Transmit information to the brain
– Two parts
• Cochlear nerves transmit sound for hearing
• Vestibular nerves sense balance and head position
Normal Action of Ears
• Air conduction
– Process of sound waves entering the ear
through pinna and traveling down the external
auditory canal to strike tympanic membrane
• Bone conduction
– Occurs as eardrum vibrates causing auditory
ossicles to vibrate
Normal Action of Ears
• Sensorineural conduction
– Occurs when sound vibrations reach inner ear
– Structures receive sound waves and relay
them to the auditory nerve for transmission to
the brain
Medical Specialties Related to Ears
• Audiologist
– Specializes in measurement of hearing
function and in rehabilitation of persons with
hearing impairments
• (audi: hearing)
• Speech-language pathologist
– Assists patients with problems related to
swallowing, speech, and communication
disorders
Pathology of Ears and Hearing
• Outer ear
– Impacted cerumen
• Accumulation of earwax forming solid mass and
adhering to the walls of external auditory canal
– Otalgia
• Pain in the ear
– (ot: ear; -algia: pain)
– Otitis
• Inflammation of the ear
Pathology of Ears and Hearing
• Outer ear
– Otomycosis
• Fungal infection of the external auditory canal
– (myc: fungus)
– Otopyorrhea
• Flow of pus from the ear
Pathology of Ears and Hearing
• Outer ear
– Otorrhea
• Any discharge from the ear
– Otorrhagia
• Bleeding from the ear
Pathology of Ears and Hearing
• Middle ear
– Barotrauma
• Pressure-related ear condition caused by pressure
changes
– Cholesteatoma
• Epidermal cyst in middle ear and/or mastoid
process made of epithelial cells and cholesterol
– (cholesteat: cholesterol)
Pathology of Ears and Hearing
• Middle ear
– Mastoiditis
• Inflammation of any part of mastoid bone
– Infectious myringitis
• Contagious inflammation causing blisters on
eardrum
– Otitis media
• Inflammation of middle ear
Pathology of Ears and Hearing
• Middle ear
– Otosclerosis
• Ankylosis of bones of middle ear
• Results in conductive hearing loss
• Treatment: stapedectomy
Pathology of Ears and Hearing
• Inner ear
– Labyrinthitis
• Inflammation of labyrinth
• May result in vertigo and deafness
– Vertigo
• Sense of dizziness and loss of balance
– Benign paroxysmal positional vertigo
• Occurs with the shift in the location of the small
crystals in semicircular canals
Pathology of Ears and Hearing
• Inner ear
– Meniere's disease
• Amount of fluid in inner ear increases
intermittently, producing vertigo, fluctuating hearing
loss, and tinnitus
– Tinnitus
• Ringing, buzzing, or roaring sound in one or both
ears
• May be associated with prolonged exposure to
loud noises
Pathology of Ears and Hearing
• Hearing loss
– Acoustic neuroma
• Brain tumor adjacent to the cranial nerve
– Deafness
• Complete or partial loss of ability to hear
– Presbycusis
• Gradual loss of sensorineural hearing related to
aging
– (-cusis: hearing)
Pathology of Ears and Hearing
• Hearing loss
– Conductive hearing loss
• Sound waves are prevented from passing air to
fluid-filled inner ear
– Sensorineural hearing loss
• Due to damage to auditory nerve or hair cells in
inner ear
Diagnostic Procedures of Ears and Hearing
• Audiological evaluation
– Measurement of the ability to hear and
understand speech sounds based on pitch
and loudness
• Audiometry
– Use of audiometer to measure hearing acuity
• (audi/o: hearing)
Diagnostic Procedures of Ears and Hearing
• Otoscope
– Instrument used to examine external ear
canal
• Monaural testing
– Involves one ear
• (mon-: one; aur: hearing)
• Binaural testing
– Involves both ears
• (bin-: two)
Diagnostic Procedures of Ears and Hearing
• Tympanometry
– Use of air pressure in ear canal for testing the
disorders of middle ear
• Acoustic reflectometry
– Tests for sound reflection from eardrum
determining amount of fluid in middle ear
• Weber and Rinne tests
– Use of tuning fork to distinguish between
conductive and sensorineural hearing losses
Treatment Procedures of Ears and Hearing
• Outer ear
– Otoplasty
• Surgical repair, restoration, or alteration of pinna
• Middle ear
– Ear tubes (tympanostomy tubes)
• Ventilating tubes inserted into the eardrum to
provide drainage for fluid and relief of pressure
Treatment Procedures of Ears and Hearing
• Middle ear
– Mastoidectomy
• Surgical removal of mastoid cells
– Myringotomy
• Surgical incision in eardrum to relieve pressure
– Stapedectomy
• Surgical removal of the top portion of the stapes
and insertion of prosthetic device
Treatment Procedures of Ears and Hearing
• Middle ear
– Tympanoplasty
• Surgical correction of damaged middle ear
• Inner ear
– Labyrinthectomy
• Surgical removal of all or portion of labyrinth
– Vestibular rehabilitation therapy
• Physical therapy to treat variety of balance
disorders
Treatments for Hearing Loss
• Assistive listening device
– Transmits, processes, or amplifies sound
– Used with or without hearing aid
• Cochlear implant
– Bypasses damaged portion of ear and directly
stimulates auditory nerve
• Fenestration
– New opening in the labyrinth to restore
hearing
Treatments for Hearing Loss
• Hearing aids
– Electronic devices worn to correct hearing
loss
– Analog hearing aid
• Uses microphone to detect/amplify sounds
– Digital hearing aid
• Computer chip converts incoming sound into code
that is filtered before being amplified