Within the petrous temporal bone lies the bony and membranous labyrinths that comprise the inner ear. Each ear’s bone labyrinth has a vestibule, three semicircular canals, and a perilymph-filled cochlea. Behind and above the vestibule are the three semicircular canals: the superior, lateral, and posterior canals. You can see the endolymph-filled membrane labyrinth inside the bony labyrinth. The membranous labyrinth comprises the utricle, saccule, cochlear duct, and three semicircular ducts. The otolith organs include the saccule and utricle. Many afferent nerve impulses reach the vestibular centers in the brain from these vestibular organs in the periphery. Static equilibrium, which keeps the head in the same position in reaction to linear acceleration of the body (such as beginning to walk or halt), is sensed by sensory receptors located in the utricle and saccule. Within the otolithic membrane are stereocilia in the hair cells of the utricle and saccule. The semicircular ducts line up with the three axes of the head’s rotation, which are at right angles to one another. The semicircular ducts are home to the sensory receptors that enable dynamic equilibrium, which keeps the head in its proper position when the body turns.