The behavior of motoneurons.

Eye movements occur when motor neurons (cranial nerves III, IV and VI) discharge and cause contractions of the extraocular muscles. Movements of the eye are influenced by several main factors: the force generated in each muscle, the inertia of the globe, the viscous and elastic properties of the muscles, and the viscoelasticity of the suspensory orbital tissues (all of which constitute the oculomotor plant). Overall, the response of the plant is sluggish, so the innervation to the muscles must have a specific time-course of activation. Otherwise, the movements of the eye would be too slow and would lead to smearing of images across the retina. Differential equations are derived that describe the activity in motoneurons and the response of the plant.