Inner Ear Function and Balance
There are many ways by which our body senses motion. The good thing is, our brain is pretty picky. Yes, it pays attention only to selected sensors and the most important motion sensor there is the inner ear itself. Eye is the second important sensor and this is practically useful for people whose inner ear function have been significantly damaged. These two motion sensors both play important part in maintaining one’s balance.
For the ear function to reach the brain, head movements of a person are being translated into electrical signals which only the brain can interpret. The said translation of signals is being done in a relative small and complex area behind the eardrum called the labyrinth or inner ear. For each ear, there are five sensors which include the saccule, utricle and the three semicircular canals. The first two are able to sense gravity and linear movements while the semicircular canals are capable of sensing circular movements. These canals are affected when one is afflicted with Benign Paroxysmal Positional Vertigo (BPPV).
The translation of the electric signals is performed by mechanoreceptor which is a hair cell. These are microscopic cell which work like on and off switches. The hairs are surrounded by fluid in the labyrinth which switches the cell and makes the electrical impulses that are transmitted into neurons as the hairs move back and forth. These signals are interpreted by the brain depending on the collection of hair cells which tells a specific movement. Through the signals these hair cells send, the body knows the direction, speed and acceleration of the movement being sensed.
The said movement is then mapped in a 3D-like manner inside the brain. From the vestibular nerve the brain gathers the signals and sends them over to the brain cortex and the cerebellum. It is in the cortex where the sensation of the movement is being felt while it is in the cerebellum where the movement is being coordinated. When there is no problem with the signal transmission, the body will get a sense of orientation and balance and the body will have no issue in reacting with the perceived motion.