The structure involved in detecting linear acceleration is the utricle and saccule, which are two chambers within the vestibular system of the inner ear.

Here's a breakdown:

* Vestibular System: This system is responsible for balance and spatial orientation. It consists of the semicircular canals (for detecting rotational movements) and the otolith organs (utricle and saccule) for detecting linear acceleration and gravity.

* Utricle and Saccule: These chambers contain a specialized sensory epithelium called the macula. The macula is covered in hair cells that are embedded in a gelatinous layer containing otoliths (small calcium carbonate crystals).

* How it works: When the head accelerates linearly, the otoliths shift due to their inertia. This movement bends the hair cells, triggering a signal that is sent to the brain via the vestibular nerve.

Therefore, the utricle and saccule, along with the otoliths and hair cells within them, are crucial for detecting linear acceleration and gravity.