the ascending branches send terminals and collaterals to the motor nuclei of the abducens, trochlear and oculomotor nerves via the ascending component of the medial longitudinal fasciculus, and are concerned in coördinating the movements of the eyes with alterations in the position of the head; the descending branches pass down in the posterior longitudinal bundle into the anterior funiculus of the spinal cord as the vestibulospinal fasciculus (anterior marginal bundle) and are distributed to motor nuclei of the anterior column by terminals and collaterals.