Equilibrium helps our bodies maintain it's balance. Equilibrium is managed in the inner ear through fluids.


The inner ear consists of bony chambers called bony labyrinth, which can be divided into three subdivisons: the cochlea, vestibule, and semicurcular canals.
Inside the inner ear are canals filled with fluid called endolymph and are also lined with hair cells. When our body is out of position the movement of the fluid is detected by the hair cells, which sends signals to the brain in order for it to compensate. Equilibrium can be divided into two types: Static Euiliqbrium and Dynamic Equilibrium.

Within the membrane sace of the
vestibule are receptors called maculae.
When the body is at rest,(i.e; STATIC= at rest)
the maculae report on the position of the head with
respect to the pull of gravity. In other words, the macule
help the brain distinguish between up and down,which
helps the head stay erect. Each macula
is a patch of receptor cells containing hairs in the
otolithic membrane, which is a gel that contains
otoliths. Otoliths are tiny stones composed of calcium
salts. When the head moves, the otoliths roll in response within the gel, activating the hair cells.
The hair cells then send impulses along the vestibular nerve to the cerebellum,informing it of the postion of the head.

Essentials of Anatomy and Physiology pg. 288

The dynamic equilibrium receptors are found in the
semicircular canals, and respond to rotary movements
of the head, rather than straight-line movements.The receptors of the semicircular canal are called crista ampullaris a sensory organ which consist of hair cells covered with a gel cap called cupula. When the head moves in an angular direction, the endomylph in the canal lag behind. Then, similar to static equilibrium, the hair cells are stimulated sending impulses through the vestibular nerve to the cerebellum.

The most common types of problems concerning balance and equilibruim usually include nausea, dizziness, and the unability to maintain balance due to what's being seen.
Meniere's Disease is a disorder in the flow of fluids in the inner ear. The cause of this disease is still unknown. A symptom of Meniere's Disease is a state of vertigo, a spinning sensation, that leads to being unbalanced, nauseated and some times vomiting. This vertigo sensation lasts about twenty minutes or even longer. The sense of being unbalance can last for days.

Other disease that can effect equilibruim and balance include labyrinthitis and BPPV.

Essentials of Anatomy and Physiology book; Chp. 8; pgs 286-288