The paths of saccadic movements of the left eye were recorded photographically for 12 normal subjects. Movements were elicited by nine small stimulus lights, arranged in a circular pattern. Each stimulus represented a five degree movement in one of eight directions, to or from the primary fixation at the center of the circular pattern.
Each direction of movement gave a distinctly different path, yet corresponding movements showed close agreement between subjects. The shapes of the paths suggest that the lateral rectus contracts consistently later than the other five extraocular muscles, regardless of the direction of the stimulus. It is possible that this delay is caused by different signal path lengths or by different propagation velocities in the neural pathways leading to the several nuclei of the oculomotor nerves.