Which of the following statements does not correctly describe the spiral organ?
a. Sounds of high frequency stimulate hair cells at the basal end.
b. The 'hairs' of the receptor cells are embedded in the tectorial membrane.
c. The basilar membrane acts as a resonator.
d. The more numerous outer hair cells are largely responsible for our perception of sound.

Verified step by step guidance

1. Step 1: Understand the structure and function of the spiral organ (organ of Corti) in the cochlea. It contains hair cells that detect sound vibrations and convert them into nerve impulses.
2. Step 2: Recall that high-frequency sounds stimulate hair cells near the basal end of the cochlea, while low-frequency sounds stimulate hair cells near the apex. This supports statement (a) as correct.
3. Step 3: Remember that the hair-like projections (stereocilia) of the receptor hair cells are embedded in the tectorial membrane, making statement (b) accurate.
4. Step 4: Recognize that the basilar membrane acts as a resonator, vibrating at different locations depending on sound frequency, which validates statement (c).
5. Step 5: Consider the roles of inner and outer hair cells: inner hair cells primarily transmit sound information to the brain, while outer hair cells amplify and fine-tune the response. Therefore, statement (d) is incorrect because outer hair cells are not mainly responsible for perception of sound.

Key Concepts

Structure and Function of the Spiral Organ (Organ of Corti)

The spiral organ, or Organ of Corti, is the sensory organ within the cochlea responsible for detecting sound. It contains hair cells whose stereocilia interact with the tectorial membrane to convert mechanical vibrations into neural signals. Understanding its anatomy is key to interpreting how sound frequencies are processed.

Tonotopic Organization of the Basilar Membrane

The basilar membrane varies in stiffness along its length, allowing it to act as a resonator that responds to different sound frequencies at specific locations. High-frequency sounds stimulate hair cells near the basal end, while low-frequency sounds affect the apical end, enabling frequency discrimination.

Role of Inner and Outer Hair Cells in Hearing

Inner hair cells primarily function as sensory receptors that send auditory information to the brain, while outer hair cells amplify and fine-tune sound vibrations. Outer hair cells are more numerous but are not the main cells responsible for perceiving sound; rather, they enhance sensitivity and frequency selectivity.