Fig. 13. Sets of contiguous 2-mm thick quasicoronal MRI images of a representative right orbit in 28 degrees of abduction (upper row), primary gaze (second row), and 28 degrees of adduction (third row). Images are ordered from posterior at left to anterior at right, with identical head positioning for all gaze positions. The colored arrow in each row demonstrates orbital layer insertion of the medial rectus (MR) muscle on its pulley. The image planes including the insertion are enlarged in the bottom row for each gaze position. The insertion of the orbital layer is seen as three dark bands running radially toward the medial orbit. The orbital layer insertion is posterior in adduction and moves two image planes (white arrow, 4 mm) anteriorly in primary gaze, and another two image planes (white arrow, 4 mm) anteriorly in abduction. IR, inferior rectus; LLA, lateral levator aponeurosis; LR, lateral rectus; SO, superior oblique; SR, superior rectus.