Sideways displacement and curved path of recti eye muscles.

We investigated the sideways displacement of recti muscles with the eye in various gaze-positions by making computed tomographic (CT) scans in a plane perpendicular to the muscle cone, posterior to the globe. We found no consistent sideways displacement of the horizontal recti in the up or down gaze or the vertical recti in the left or right gaze. We found a substantial displacement, however, of the contracting and relaxing muscles. Consequently, we made CT scans in a horizontal plane through medial and lateral recti and found that, with the eye in primary position, the recti muscles follow a curved path. The curvature of the path increased following muscle relaxation and decreased following muscle contraction.