MCAT Social and Behavioral Sciences : Physiology of the Ear
Study concepts, example questions & explanations for MCAT Social and Behavioral Sciences
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Example Questions
Example Question #1 : Hearing
Which of the following is not a cause of a conductive hearing loss?
Loud noises
Impacted cerumen
Foreign body in the external ear canal
Perforated eardrum
Acute otitis media
Loud noises
Conductive hearing loss occurs when sound is not conducted through the external auditory canal to the tympanic membrane and the ossicles. Causes include acute otitis media, performated eardrum, impacted cerumen (earwax), or a foreign body in the external canal. A sensorineural hearing loss occurs when there is damage to the fine hairs in the cochlea caused by loud noise.
Example Question #1 : Physiology Of The Ear
Which of the following is not a bone of the middle ear?
Pinna
Incus
Stapes
Malleus
Pinna
The "malleus," "incus," and "stapes" are the three bones that make up the ossicles of the middle ear. Together they work to transform sound waves into mechanical vibrations. The "pinna" is not a bone at all, but rather the anatomical term for the fleshy, cartilaginous outer ear.
Example Question #2 : Hearing
Sound waves enter the outer ear and vibrate the tympanic membrane, which causes the transmission of sound waves through the ossicles to the inner ear. In what order do the ossicles vibrate?
Incus, malleus, and stapes
Incus, stapes, and malleus
Malleus, incus, and stapes
Stapes, malleus, and incus
Malleus, incus, and stapes
The ossicle that attaches directly to the tympanic membrane is the malleus, or "hammer." This bone articulates with the incus, or "anvil," which then articulates with the stapes, or "stirrup" (so called because of it's resemblance to the stirrup of a saddle). The stapes in turn attaches to the oval window of the fluid-filled inner ear.
Example Question #3 : Hearing
Which of the following structures is the main sensory organ associated with hearing?
Bony labyrinth
Eustachian tube
Tympanic membrane
The scala tympani
Organ of Corti
Organ of Corti
The main sensory organ of hearing is a small structure within the cochlea called the “organ of Corti.” It contains hair cells, which are sensory receptor cells capable of responding to changes in pressure of the fluid of the inner ear. The organ of Corti is sandwiched between the three fluid-filled chambers, or scalae: the scala vestibuli, the scala tympani, and the scala media.
The “bony labyrinth” is a separate part of the inner ear that plays a role in balance and equilibrium. The “eustachian tube” is not a part of the inner ear, but rather a channel between the middle ear and the pharynx.
Example Question #4 : Hearing
Which of the following is not a function of the eustachian tube?
Equalization of pressure in the middle ear
Removal of cellular and bacterial waste
Drainage of fluid from the middle ear
Production of perilymph
Production of perilymph
The eustachian tube primarily functions to equalize pressure between the middle ear and the atmosphere, remove cellular and bacterial waste from the middle ear, and to drain fluid from the middle ear into the pharynx. Cells within the inner ear produce perilymph.
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