Fig. 12 Basic open-loop block diagram of the vestibuloocular mechanism (heavy lines) superimposed on the block diagram of the total ocular motor control system. The input is head acceleration, which is converted by the semicircular canals to a neural signal proportional to head velocity and sent to the vestibular nuclei. Here the motor commands are generated and passed on to the ocular motor nuclei (OMN). This innervation causes the extraocular muscles (EOM) to move the eyes with an SEM in an attempt to match head velocity and with an FEM if eye position requires change consequent to an internal centering mechanism. Absolute eye position is the sum of relative eye position and the nonzero head position. The dashed lines show the mathematical relationships between head position and acceleration; they are not signal paths.