page_title: Sense of balance
section_title: Neural
hierarchical_section_title: Sense of balance / System overview / Neural
caption_attribution_description: balance disorder image from public domain http://www.nidcd.nih.gov/health/balance/balance_disorders.asp Descriptions of how the otolith organs (pictured here) of the inner ear enable humans and other animals to sense gravitation and acceleration are at Otolith, at Equilibrioception and at Vestibular system. What enables humans and other animals to keep themselves balanced is their brain's comparison of information from the vestibular system (which is comprised of three semicircular canals and two otolith organs in each ear), the visual system and the proprioceptive system.
context_page_description: The sense of balance or equilibrioception is the perception of balance and spatial orientation. It helps prevent humans and nonhuman animals from falling over when standing or moving. Equilibrioception is the result of a number of sensory systems working together: the eyes, the inner ears, and the body's sense of where it is in space ideally need to be intact.
  The vestibular system, the region of the inner ear where three semicircular canals converge, works with the visual system to keep objects in focus when the head is moving. This is called the vestibulo-ocular reflex. The balance system works with the visual and skeletal systems to maintain orientation or balance. Visual signals sent to the brain about the body's position in relation to its surroundings are processed by the brain and compared to information from the vestibular and skeletal systems.
context_section_description: First order vestibular nuclei (VN) project to IVN, MVN, and SVN.
  The inferior cerebellar peduncle is the largest center through which balance information passes. It is the area of integration between proprioceptive, and vestibular inputs to aid in unconscious maintenance of balance and posture.
  Inferior olive nucleus (also known as the olivary nucleus) aids in complex motor tasks by encoding coordinating timing sensory info; this is decoded and acted upon in the cerebellum.
  Cerebellar vermis has three main parts: vestibulocerebellum (eye movements regulated by the integration of visual info provided by the superior colliculus and balance info), spinocerebellum [integrates visual, auditory, proprioceptive, and balance info to act out body and limb movements. Trigeminal and dorsal column (of spinal cord) proprioceptive input, midbrain, thalamus, reticular formation and vestibular nuclei (medulla) outputs], and cerebrocerebellum (plans, times, and initiates movement after evaluating sensory input from, primarily, motor cortex areas, via pons and cerebellar dentate nucleus. It outputs to thalamus, motor cortex areas, and red nucleus).
  Flocculonodular lobe is a cerebellar lobe that helps maintain body equilibrium by modifying muscle tone (continuous and passive muscle contractions).
  MVN and IVN are in the medulla, LVN and SVN are smaller and in pons. SVN, MVN, and IVN ascend within medial longitudinal fasciculus (MLF). LVN descend the spinal cord within the lateral vestibulospinal tract and end at sacrum. MVN also descend the spinal cord, within the medial vestibulospinal tract, ending at lumbar 1.
  Thalamic reticular nucleus distributes information to various other thalamic nuclei, regulating the flow of information. It is speculatively able to stop signals, ending transmission of unimportant info. The thalamus relays info between pons (cerebellum link), motor cortices, and insula.
  Insula is also heavily connected to motor cortices; insula is likely where balance is likely brought into perception.
  The oculomotor nuclear complex refers to fibers going to tegmentum (eye movement), red nucleus (gait (natural limb movement)), substantia nigra (reward), and cerebral peduncle (motor relay). Nucleus of Cajal are one of the named oculomotor nuclei, they are involved in eye movements and reflex gaze coordination.
  Abducens solely innervates the lateral rectus muscle of the eye, moving the eye with trochlear. Trochlear solely innervates the superior oblique muscle of the eye. Together, trochlear and abducens contract and relax to simultaneously direct the pupil towards an angle and depress the globe on the opposite side of the eye (e.g. looking down directs the pupil down and depresses (towards the brain) the top of the globe). The pupil is not only directed but often rotated by these muscles. (See visual system)
  
  The thalamus and superior colliculus are connected via lateral geniculate nucleus. Superior colliculus (SC) is the topographical map for balance and quick orienting movements with primarily visual inputs. SC integrates multiple senses.
caption: Illustration of the flow of fluid in the ear, which in turn causes displacement of the top portion of the hair cells that are embedded in the jelly-like cupula. Also shows the utricle and saccule organs that are responsible for detecting linear acceleration, or movement in a straight line.
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