What is the function of the crista ampullaris in dynamic equilibrium?

What is the function of the crista ampullaris in dynamic equilibrium?

• A. It encodes rotational movement of the head.
• B. It encodes linear acceleration of the head.
• C. It detects gravity changes.
• D. It processes auditory signals.

Answer: (A)

The crista ampullaris is the sensory organ inside the ampulla of each semicircular canal that detects angular (rotational) head movement. It contains hair cells with stereocilia and a kinocilium embedded in a gelatinous cupula. When the head rotates, the endolymph inside the canal lags behind due to inertia, bending the cupula and deflecting the hair bundles. This deflection changes the hair cells’ receptor potentials and alters the firing rate of the vestibular nerve, signaling rotational velocity to the brain. This drives dynamic equilibrium, distinguishing rotational movement from linear acceleration. Linear acceleration and gravity are detected by the maculae in the utricle and saccule, while auditory signals come from the cochlea, not the vestibular organs.

The crista ampullaris is the sensory organ inside the ampulla of each semicircular canal that detects angular (rotational) head movement. It contains hair cells with stereocilia and a kinocilium embedded in a gelatinous cupula. When the head rotates, the endolymph inside the canal lags behind due to inertia, bending the cupula and deflecting the hair bundles. This deflection changes the hair cells’ receptor potentials and alters the firing rate of the vestibular nerve, signaling rotational velocity to the brain. This drives dynamic equilibrium, distinguishing rotational movement from linear acceleration. Linear acceleration and gravity are detected by the maculae in the utricle and saccule, while auditory signals come from the cochlea, not the vestibular organs.