Medical Terminology_ A Word-Building Approach 7th Edition rice_ch15

Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,Copyright 2012 by Pearson Education, Inc.,All rights reserved.,Medical Terminology: A Word-Building Approach, Seventh Edition,Jane Rice,Medical Terminology,A Word-Building Approach,Copyright 2012 by Pearson Education, Inc.,All rights reserved.,Medical Terminology: A Word-Building Approach, Seventh Edition,Jane Rice,CHAPTER,Seventh Edition,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,Special Senses:,The Ear,15,Learning Outcomes,State the description and primary functions of the ear.,Analyze, build, spell, and pronounce medical words.,Comprehend the drugs highlighted in this chapter.,Describe diagnostic and laboratory tests related to the ear.,Identify and define selected abbreviations.,Anatomy and Physiology Overview,The ear is generally described as having three distinct divisions, each with distinct functions:,External ear,Middle ear,Inner ear,The ear contains structures for both the sense of hearing and the sense of balance.,Anatomy and Physiology Overview,Eighth cranial nerve:,Also called the acoustic or auditory nerve.,Carries nerve impulses for both hearing and balance from the ear to the brain.,Figure 15.1,The ear and its anatomic structures.,External Ear,The appendage on the side of the head consisting of:,Auricle or pinna,External acoustic meatus,External Ear,Auricle (pinna):,Protects the tympanic membrane (eardrum).,Collects and directs sound waves through the ear canal to the eardrum.,Ear canal contains modified sweat glands that secrete cerumen, or earwax.,Too much cerumen can block sound transmission.,Middle Ear,Separated from external ear by eardrum.,An air-filled cavity (tympanic cavity) carved out of the temporal bone.,This cavity contains three specialized small bones or ossicles that mechanically transmit sound vibrations:,malleus (hammer),incus (anvil),stapes (stirrup),Middle Ear,During transmission, tympanic vibrations can be amplified as much as 22 times their original force.,Figure 15.2,The ossicles of the middle ear along with the oval window and tympanic membrane.,Middle Ear,The tympanic cavity connects to the throat/nasopharynx via the eustachian tube.,This ear/throat connection makes the ear susceptible to infections, such as otitis media (OM) and mastoiditis.,The eustachian tube equalizes air pressure to ensure the eardrum vibrates maximally when struck by sound waves.,Life Span Considerations,At 36 weeks, the ear lobes of the fetus are soft.,Around 40 weeks, the fetuss ear lobes become firm.,In newborns, the wall of the ear canal is pliable because of underdeveloped cartilage and bone.,Life Span Considerations,The eustachian,tube in infants is shorter and straighter than in older children and adults.,Because of this, an infant or young child is more predisposed to developing an ear infection.,When ear infection occurs, the child,s ears should be examined very carefully.,Figure 15.3,To examine a child,s ear, the pinna should be pulled back and up for children over 3 years; the pinna should be pulled down and back for children under 3 years of age.,Inner Ear,Consists of a membranous labyrinth or mazelike network of canals located within a bony labyrinth.,These structures are called labyrinths because of their complicated shapes.,Inner Ear,The bony labyrinth, located in the temporal bone, consists of the:,Cochlea,Vestibule,Three semicircular canals,Inner Ear,The membranous labyrinth, separated from the bony labyrinth by fluid called perilymph:,is filled with a fluid called endolymph.,contains the actual hearing cells, the hair cells of the organ of Corti.,Inner Ear,Cochlea,Spiral-shaped bony structure containing the cochlear duct.,The spiral cavity of the bony cochlea is partitioned into three tubelike channels, which are formed by the:,Basilar membrane,Forms the lower channel or scala tympani.,Organ of Corti is located on the basilar membrane.,Vestibular membrane (Reissner,s membrane),Forms the upper channel or scala vestibuli.,Figure 15.4,The cochlea.,Inner Ear,Process of Hearing,Sound waves are directed to the eardrum, causing it to vibrate.,These vibrations move the three small bones of the middle ear (malleus, incus, and stapes).,Movement of stapes at oval window sets up pressure waves in the perilymph and endolymph.,Inner Ear,Process of Hearing,The waves cause vibration of hair cells of the organ of Corti.,These vibrations are picked up by auditory nerve fibers that transmit an electric nerve signal to the cerebral cortex of the brain, where it is interpreted as sound.,Figure 15.5,Path of sound vibrations.,Inner Ear,Vestibule,A bony structure located between the cochlea and the three semicircular canals.,Contains the utricle,and saccule, membranous pouches containing perilymph.,Utricle:,communicates with semicircular canals,contains hair cell sensory receptors connected to fibers from the eighth cranial nerve,These hair cells are a part of the sense of equilibrium.,Inner Ear,Semicircular Canals,Superior, posterior, and inferior semicircular canals are located at right angles to each other.,At the base of each canal is an enlargement called an ampulla containing nerve endings in the form of hair cells.,Inner Ear,Semicircular Canals,Dizziness and motion sickness are associated with the continued movement of the fluid in the semicircular canals due to gravitational influences and the resulting sensory sensation in these areas.,Life Span Considerations,With aging, changes occur in the external, middle, and inner ear.,The skin of the auricle can become dry and wrinkled.,Production of cerumen declines and is drier.,Life Span Considerations,Dryness of the external canal causes itching.,Hairs in the external canal become coarser and longer, especially in males.,Life Span Considerations,The eardrum thickens, and the bony joints in the middle ear degenerate.,Hearing loss, known as presbycusis, results from degenerative changes in the inner ear.,Changes in the inner ear affect:,sensitivity to sound,understanding of speech,balance,Life Span Considerations,Degenerative changes include atrophy of:,the cochlea,the cochlear nerve cells,the organ of Corti,These changes lead to the hearing loss, presbycusis, that is common in the older adult.,Life Span Considerations,Noisy surroundings make it difficult for older adults to discriminate between sounds, thereby impairing communication and socialization.,The hearing distance of older adults can also be impaired.,Figure 15.6,A child with a hearing impairment wears a hearing aid (as noted in his left ear).,Life Span Considerations,Sustained noise over 85 decibels (db, dB) can cause permanent hearing loss.,Risk doubles with each 5-decibel increase.,About 2 in every 10 teens have lost some of their hearing ability from exposure to noise and are not aware of it.,Life Span Considerations,17% of middle and high school students have some hearing loss.,High-pitched sounds are the first to be affected by noise exposure.,As hearing loss progresses, a person can start to have difficulty hearing, particularly when there is background noise.,Life Span Considerations,Excessive noise can permanently damage the hair cell sensory receptors of the organ of Corti.,These receptors are instrumental in transmitting sound to the brain.,Figure 15.7,Listening to loud music with headphones or at rock concerts is a frequent cause of hearing loss among teenagers and young adults.,Life Span Considerations,Otitis media is often difficult to detect in children who do not yet have sufficient speech and language skills.,Life Span Considerations,Common signs of otitis media include:,Unusual irritability; fussiness.,Difficulty sleeping; night awakening.,Tugging or pulling at one or both ears.,Fever.,Fluid draining from the ear.,Loss of balance.,Unresponsiveness to quiet sounds, sitting too close to the T.V., or being inattentive.,Life Span Considerations,Children age 2 and younger who attend day care centers are 36 times more likely to contract ear infections, pneumonia, and meningitis than stay-at-home children.,Most middle ear infections are a result of an upper respiratory infection (URI) that has spread through the eustachian tube.,Figure 15.8,This young child is pulling at the ear and acting fussy, two important signs of otitis media.,Figure 15.9,Examination of ear using otoscope.,Figure 15.10,Thermoscan thermometer. (Courtesy of Thermoscan, inc. San Diego, CA),Figure 15.11,Use of the tympanic thermometer to measure body temperature.,Drug Highlights,Analgesic,Antipyretic,Antibiotics,Penicillins,Cephalosporins,Tetracyclines,Erythromycin,Drug Highlights,Drugs Used to Treat Vertigo,Vertigo is a sensation of movement.,Diagnostic and Lab Tests,Auditory-evoked response,Response to auditory stimuli (sound) that can be measured independently of the patient,s subjective response.,Use of an electroencephalograph can determine the intensity of sound and presence of response.,Diagnostic and Lab Tests,Electronystagmography (ENG),Recording eye movement in response to specific stimuli, such as sound.,Diagnostic and Lab Tests,Pure tone audiometry,Method of testing pure tones by providing calibrated tones to a person via earphones, allowing that person to increase the sound level until it can just be heard.,Hearing tests of right and left ears are generally done independently.,The results of such tests are summarized in audiograms.,Diagnostic and Lab Tests,Otoscopy,Visual examination of the external auditory canal and the tympanic membrane via an otoscope.,Tuning fork test,Method of testing hearing by the use of a tuning fork.,Two types of hearing loss, conductive and perceptive, may be distinguished through the use of this test.,Diagnostic and Lab Tests,Rinne Test,Uses a tuning fork to compare bone conduction hearing with air conduction.,Tympanometry,Measurement of the movement of the tympanic membrane and pressure in the middle ear.,Figure 15.13,Administration of the Rinne test.,Abbreviations,