Utricle (ear)

Utricle (ear)

The utricle or utriculus is a part of the inner ear's vestibular system, which contributes to our sense of balance and spatial orientation. It is one of two otolith organs, the other being the saccule. The utricle and saccule together are responsible for detecting linear accelerations and head-tilts in relation to gravity.

The utricle and saccule, two of the vestibular organs in the inner ear.

Structure

The utricle is a small, fluid-filled sac located in the vestibule of the inner ear. It is approximately 2-3 mm in diameter and is oriented horizontally in the head. The interior of the utricle contains a region called the macula, which is covered in sensory hair cells. These cells are embedded in a gelatinous layer topped with tiny calcium carbonate crystals called otoliths.

Function

The primary function of the utricle is to detect changes in horizontal movement and head-tilt. When the head moves or tilts, the weight of the otoliths causes the gelatinous layer to shift, which in turn bends the hair cells. This bending triggers an electrical signal that is sent to the brain via the vestibular nerve. The brain interprets these signals to determine the body's orientation and movement.

Clinical significance

Disorders of the utricle can lead to a variety of balance and spatial orientation problems, such as vertigo, dizziness, and imbalance. One common condition is benign paroxysmal positional vertigo (BPPV), which occurs when the otoliths become dislodged and move into the semicircular canals. This can cause brief episodes of severe dizziness and imbalance, typically triggered by changes in head position.

See also

• Semicircular canals
• Vestibular system
• Otolith
• Vestibular nerve
• Benign paroxysmal positional vertigo