During horizontal gaze, the medial longitudinal fasciculus (MLF) on each side of the brain stem enables abduction of one eye to be coordinated with adduction of the other. The MLF connects the following structures: Sixth cranial nerve nucleus (which controls the lateral rectus, responsible for abduction) Adjacent horizontal gaze center (paramedian pontine reticular formation) Contralateral third cranial nerve nucleus (which controls the medial rectus, responsible for adduction) The MLF also conn