A standing subject looking over her left shoulder suddenly rotates her head to look over her right shoulder. How does the vestibular system detect this motion?

Fluid within the semicircular canals remains stationary, bending the cupula and stereocilia as the head rotates

Explanation:

Vestibular system is a sensory system that helps to maintain the body shape by checkmating the its motion.Thus, this assists the body in achieving its equilibrium via positioning of the head in a balanced form. In the vestibular system, there exists an organ that put in place the rotation of the head in any manner we could ever think of. Either sideway rotation, up or down, left or right. This organ is known to be semicircular canals.

In the semicircular canals, there exists a stereocilia and a gelatinous mass.This gelatinous mass encircles the stereocilia. NOW, if a standing subject looking over her left shoulder suddenly rotates her head to look over her right shoulder; this cause the gelatinous mass that encircles the stereocilia to move thereby making the fluid within it to remain stationary.

Explanation: vestibular system is responsible for control during motion. The

Vestibular receptors lie in the inner ear, they detect head turn linear motions (rotational motion) ,translators and tilts of head relative to gravity,and make this motions into neutral signals,that is sent to the brain. When a left head turn is made,the left horizontal vestibular will increase their vestibular nuclei neutrons projecting to the opposite right abducens nucleus.