Which portion of the inner ear contains utricles and saccules?

The correct choice is the vestibule, which is the part of the inner ear that contains the utricle and saccule, essential components of the vestibular system. The vestibule is responsible for detecting linear acceleration and head position relative to gravity. The utricle and saccule contain specialized sensory epithelium called the macula, which is equipped with hair cells that respond to changes in head position as well as gravitational forces.

The cochlea is specifically involved in hearing, converting sound vibrations into neural signals, and does not contain the utricles and saccules. The semi-circular canals, on the other hand, are oriented in three dimensions and are primarily responsible for detecting rotational movements of the head. The tympanic membrane, commonly known as the eardrum, is not part of the inner ear at all, as it separates the outer ear from the middle ear and plays a role in sound transmission rather than balance.

Understanding the functions and locations of these structures is crucial for grasping how the auditory and balance systems operate in the inner ear.