(2) (anatomy) The small indentation in the prostrate
(3) (botany) A thin bladder-like pericarp
(4) (botany) A small sac-like, air-filled structure in certain seaweeds
In anatomy, the utricle is one of the two parts of the otolith organ of the inner ear. The other part is the saccule. The otolith organ is a collective term for the utricle and saccule and functions in detecting gravitational forces essential in keeping balance. The otolith organ is part of the vestibular system. Both the utricle and the saccule are filled with fluid and lined with tiny hairs. There are crystals attached to the hairs. When the head moves (e.g. tilts), the crystals move through the fluid and rub against the hairs. This movement is sensed by the hairs, which then send as signals to the brain. The brain processes this information and relays it to the eyes, muscles, and joints, which respond by keeping the body in balance and maintaining spatial orientation.
Another anatomical use of the utricle is the prostatic utricle, which is the small indentation in the prostatic urethra.
Word origin: Latin utriculus ("leather bag")