That's absolutely correct! This parasagittal slice of the brain demonstrates where the oculomotor, trochlear, and abducens nuclei are in the midbrain and pons in relation to the horizontal, vertical, and conjugate gaze centers. The long white tract just beneath them contains the medial longitudinal fasciculus (MLF) by which the conjugate movements of the eyes are coordinated. A lesion in the left MLF would stop the message to the left oculomotor nerve to contract the left medial recus in conjunction with the right lateral rectus. But the left medial rectus does work when convergence was tested in the H-test. That's because the convergence center is anterior to this MLF lesion so the message can still reach both oculomotor nerves to stimulate both medial rectus muscles. Return to the case to review the wrong answer choices, or return to the table of contents.