A 65-year-old male complains of difficulty hearing high-pitched sounds. Which region of the cochlea is primar… - INI-CET EXAM -2025

INI-CET EXAM -2025

Applied Physiology

Easy

Appeared in: INI-CET EXAM -2025

Explanation

The cochlea has a tonotopic map, where different frequencies are processed at different locations.
The base of the cochlea is narrow and stiff, making it physically tuned to vibrate in response to high-frequency (high-pitched) sounds.
Age-related hearing loss (presbycusis) and noise-induced hearing loss typically damage the hair cells at the base of the cochlea first.
Therefore, a complaint of difficulty hearing high-pitched sounds correlates directly with damage to the basal region of the cochlea.

Option A: The apex of the cochlea is responsible for processing low-frequency (low-pitched) sounds.
Option C: The stria vascularis produces endolymph and maintains the cochlea's ionic balance. While its dysfunction causes hearing loss, it's not the primary site of frequency-specific damage as described in the question.
Option D: The tectorial membrane is a gelatinous structure that interacts with the stereocilia of the hair cells. Damage to it would disrupt the mechanical transduction of sound but does not explain the specific loss of only high frequencies.

Visual 1: Diagram: An 'unrolled' cochlea illustrating the tonotopic map. This visual should clearly label the 'Base' with 'High Frequencies' and the 'Apex' with 'Low Frequencies' to reinforce the core concept.
Visual 2: Infographic: A chart comparing the characteristics of the cochlear base and apex, including stiffness, width, and the corresponding sound frequencies they process.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Tonotopic organization of the cochlea and pathophysiology of presbycusis as background academic context rather than a clinical decision trigger.
This question addresses presbycusis, the most common type of sensorineural hearing loss caused by the natural aging of the auditory system. Nurses will frequently encounter older adults with this condition.
Nursing assessment should include asking about hearing difficulties. When communicating with a patient with high-frequency hearing loss, nurses should face the patient, speak clearly, and lower the pitch of their voice, as these patients often have more trouble understanding higher-pitched female or children's voices.
Patient safety is a key concern. High-frequency hearing loss can prevent a person from hearing important environmental sounds like smoke alarms, phone rings, or car horns, increasing their risk of accidents.

How to Approach the Question

First, identify the key information in the stem: the patient has difficulty hearing 'high-pitched sounds'.
Recall or deduce the functional anatomy of the inner ear, specifically the cochlea.
Remember the principle of tonotopic organization: the cochlea is organized by frequency.
Associate 'high pitch' with the 'base' of the cochlea and 'low pitch' with the 'apex'. A helpful mnemonic is that the base is narrow and stiff, like the high strings on a piano, while the apex is wide and floppy, like the low strings.
Evaluate the options based on this principle. 'Base of cochlea' directly matches the symptom of high-pitched hearing loss.
Eliminate the other options: the apex is for low pitches, and the stria vascularis and tectorial membrane have different primary functions.

Concept Tested & Keywords

Concept Tested: Tonotopic organization of the cochlea and pathophysiology of presbycusis.
Stem keywords: difficulty hearing, high-pitched sounds, cochlea, damaged
Lead-in keywords: Which region
Clinical cues: 65-year-old male (suggests age-related changes)
Clinical cues: difficulty hearing high-pitched sounds (specific symptom pointing to a location)

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