The otolith, also known as the statolith, is a sensory structure found in the inner ear of vertebrates that is responsible for the detection of gravity and linear acceleration [1]. The otolith is composed of a variety of components, including calcium carbonate (CaCO3), proteins, and lipids [2]. The otolith is essential for balance and orientation as it is sensitive to changes in gravity and acceleration [3].
Otoliths are composed of two primary components, the utricle and the saccule. The utricle is located posteriorly and contains two distinct areas, the macula and the striola. The macula is located near the center of the utricle and is responsible for sensing linear acceleration. The striola is located near the edge of the utricle and is responsible for sensing gravity. The saccule is located anteriorly and is responsible for sensing angular acceleration [4].
The otoliths are connected to the vestibular system via the otolithic membrane. This membrane is highly sensitive to mechanical deformation and contains a variety of receptor proteins, such as the transmembrane protein Prestin, which is responsible for detecting changes in acceleration and gravity [5].
The otolith is also connected to the endolymphatic sac, a structure located posteriorly in the inner ear. The endolymphatic sac plays an important role in the regulation of the endolymphatic fluid, which is essential for maintaining balance and orientation [6].
The otolith has been studied extensively in both humans and animals. Studies have found that the otolith is capable of detecting even small changes in acceleration and gravity, which is essential for maintaining balance and orientation [7]. Additionally, research has found that the otolith is capable of responding to changes in the environment, such as changes in temperature or humidity [8].
Overall, the otolith is an essential sensory structure for maintaining balance and orientation in both humans and animals. Its ability to detect small changes in acceleration and gravity is essential for maintaining balance and orientation. Further research is needed to better understand the structure and function of the otolith.
References
1. Curthoys IS. The otolith organs. In: Fetter M, editor. Comprehensive Physiology. Hoboken, NJ: John Wiley & Sons, Inc; 2011. p. 455–491.
2. Beraneck M, Magnin M. The Otoliths: Structure and Function. International Review of Neurobiology. 2017;132:1-34.
3. Guedry FE. The Physiology of Fishes. Boca Raton: CRC Press; 2002.
4. Popper AN, Fay RR. The Physiology of Fishes. New York: Academic Press; 1995.
5. Kaczmarek KL, Weinberger NM. Otolithic Membrane: Structural Properties and Sensory Function. In: Bock GR, editor. Physiology of the Ear. San Diego: Academic Press; 2001. p. 149–160.
6. Van de Berg R, Van den Berg T. Pathophysiology of the Vestibular System. London: Springer; 2011.
7. Curthoys IS, Halmagyi GM, Goebel JA. Human Vestibular Physiology. Oxford: Oxford University Press; 2006.
8. Dabdoub A, Bance M. Vestibular Physiology. In: Bilton BD, editor. Handbook of Clinical Neurology. Amsterdam: Elsevier; 2014. p. 599–633.