# A nurse is assessing a client's ear anatomy. Which structure is responsible for transmitting sound vibrations from the tympanic membrane to the inner ear? > source: MyMerci (mymerci.kr) > url: https://mymerci.kr/pages/nclex_q.php?qn_id=541632 > language: ko > subject: Adult Health ## 문제 A nurse is assessing a client's ear anatomy. Which structure is responsible for transmitting sound vibrations from the tympanic membrane to the inner ear? ## 보기 1. Ossicles (malleus, incus, stapes) **✔ 정답** 2. Eustachian tube 3. Semicircular canals 4. Cochlear nerve **정답: 1** ## 해설 The ossicles (malleus, incus, stapes) transmit sound vibrations from the tympanic membrane to the inner ear. Other structures like the Eustachian tube, semicircular canals, or cochlear nerve have different functions in hearing or balance. ## 심화 해설 Anatomical Pathway of Sound Conduction Sound waves traveling through the air must be converted into mechanical energy and then into fluid waves to be perceived by the brain. The structure bridging the air-filled outer ear and the fluid-filled inner ear is the chain of auditory ossicles located in the middle ear. According to the provided anatomical reference, the middle ear is an air-filled cavity that lies between the tympanic membrane laterally and the oval window medially. The primary function of this cavity is to house the three bones that physically carry sound inward. The correct answer is the ossicles (malleus, incus, stapes). The reference explicitly states that these three bones "transmit and amplify sound vibrations from the tympanic membrane to the oval window." The process begins when sound waves strike the tympanic membrane, causing it to vibrate. This vibration moves the malleus (attached to the membrane), which then articulates with the incus, which in turn moves the stapes. The footplate of the stapes rocks against the oval window, acting as a piston to transfer mechanical energy into the fluid-filled inner ear, thereby initiating the hearing mechanism. The other options represent structures with different, distinct roles that do not involve the direct mechanical transmission of vibrations from the tympanic membrane to the inner ear. The Eustachian tube connects the middle ear to the nasopharynx and serves to equalize air pressure on both sides of the tympanic membrane, but it does not transmit sound. The semicircular canals are part of the inner ear's vestibular system responsible for balance and spatial orientation, not hearing. The cochlear nerve (part of the vestibulocochlear nerve) carries the electrical impulses generated in the cochlea to the brain for interpretation; it is a neural structure, not a mechanical vibratory conductor. For the NCLEX-RN, it is crucial to differentiate the structures of the ear by their physiological function: the outer ear collects sound, the middle ear mechanically conducts and amplifies sound via the ossicles, and the inner ear converts mechanical energy into neural signals. Damage to or fixation of the ossicles (such as in otosclerosis, commonly affecting the stapes) results in a conductive hearing loss, where sound cannot be physically transmitted to the inner ear, a concept distinct from sensorineural loss involving the cochlea or nerve. ## 임상 시나리오 Middle Ear Sound ConductionOssicular Chain Function The ossicles (malleus, incus, stapes) form a lever system that mechanically transmits vibrations from the tympanic membrane to the oval window. This process amplifies sound by approximately 25 dB to overcome the impedance mismatch between air and inner ear fluid. Assess the tympanic membrane with an otoscope before assuming ossicular dysfunction. A cone of light at the 5 o'clock (right ear) or 7 o'clock (left ear) position indicates a normal, intact membrane. CautionConductive hearing loss from ossicular disruption (e.g., otosclerosis) often presents with a negative Rinne test (bone conduction > air conduction). Do not confuse this with sensorineural loss from cochlear or nerve damage. ## 핵심 개념 - **Ossicles** — Three small bones (malleus, incus, stapes) in the middle ear that form a mechanical chain to transmit and amplify sound vibrations from the tympanic membrane to the oval window. - **Tympanic membrane** — The eardrum; a thin membrane that vibrates when struck by sound waves, initiating the mechanical transmission of sound in the middle ear. - **Eustachian tube** — A canal connecting the middle ear to the nasopharynx that equalizes air pressure on both sides of the tympanic membrane. - **Semicircular canals** — Three fluid-filled structures in the inner ear that detect rotational head movements and are essential for balance and spatial orientation. - **Cochlear nerve** — The nerve that transmits auditory signals from the cochlea in the inner ear to the brainstem for sound perception. ## 같은 주제 문제 - [A nurse is assessing a 65-year-old patient with vertigo. 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