Which components detect linear acceleration and head tilt?

• A. Semicircular canals
• B. Cochlea
• C. Proprioceptors
• D. Otolith organs (utricle and saccule)

Answer: (D)

The main idea is that linear acceleration and head tilt are detected by the otolith organs in the vestibular system. The otolith organs, consisting of the utricle and saccule, contain maculae with hair cells embedded in a gelatinous layer topped by otolith crystals (statoconia). When the head moves in a straight line or tilts, the inertia of the otoliths causes them to lag behind the changes in head position, bending the hair bundles. This deflection alters the hair cells’ firing rates and signals linear acceleration and tilt to the brain. The utricle is most responsive to horizontal movements and tilting in the horizontal plane, while the saccule responds to vertical accelerations.

In contrast, the semicircular canals detect angular (rotational) movements through endolymph flow that deflects the cupula, and the cochlea handles hearing. Proprioceptors sense body position via muscles and joints, not inner-ear sensing.