(Science: physiology) Collective term for those fibres (corticonuclear fibres) which separate from the corticospinal tract in the course of the latter's descent through the pons and medulla oblongata.
fibres of this tract innervate the motor nuclei of the trigeminal, facial, and hypoglossal nerves (perhaps also the nucleus ambiguus), directly and by way of interneurons in the lateral part of the rhombencephalic tegmentum.
no direct supranuclear cortical innervation of the motor nuclei innervating the external eye muscles (oculomotor, trochlear, abducens) has been identified. Fibres of the corticobulbar tract also project into the formatio reticularis (i.e., corticoreticular fibres) and terminate upon sensory relay nuclei (e.g., gracile and cuneate nuclei, nucleus spinalis trigeminalis and nucleus solitarius).
Synonym: tractus corticobulbaris.