Vestibulospinal

Vestibulospinal refers to a set of descending motor pathways that originate in the vestibular nuclei of the brainstem and project to the spinal cord to regulate posture, balance, and muscle tone in response to head movement and gravity. The term typically denotes two principal tracts: the medial vestibulospinal tract (MVST) and the lateral vestibulospinal tract (LVST).

The MVST originates mainly from the medial vestibular nucleus and descends medially and often bilaterally in the cervical and upper thoracic spinal cord. It predominantly influences neck and upper trunk muscles and participates in vestibulocollic reflexes that stabilize the head during body movement and coordinate head position with eye movements.

The LVST arises from the lateral vestibular nucleus (Deiters’ nucleus) and descends ipsilaterally through the ventral (anterior) funiculus to multiple spinal levels. It exerts strong facilitatory effects on extensor muscles of the limbs and trunk, supporting upright posture and rapid postural adjustments in response to perturbations. It contributes to anti-gravity muscle tone and overall balance.

Together, these tracts integrate input from the vestibular apparatus (semicircular canals and otolith organs) with proprioceptive signals to maintain posture and coordinated movement. They interact with other descending systems, such as the reticulospinal and corticospinal tracts, and with reflex pathways that influence gaze and posture.

Clinical relevance: lesions affecting vestibulospinal pathways can impair postural control, balance, and muscle tone, leading to trunk instability, gait disturbances, or ataxia in some cases.