From Wikipedia, the free encyclopedia
The corticobulbar (or corticonuclear) tract is a white matter pathway connecting the cerebral cortex to the brainstem (the term "bulbar" referring to the brainstem).
The 'bulb' is an archaic term for the medulla oblongata. In clinical usage, it includes the pons as well.
[edit] Function
The muscles of the face, head and neck are controlled by the corticobulbar system, which terminates on motor neurons within brainstem motor nuclei. This is in contrast to the corticospinal tract, which connects the cerebral cortex to spinal motor neurons, and controls movement of the torso, upper and lower limbs.
The Corticobulbar tract runs through the genu of the internal capsule as it passes from the motor cortex down through to the brainstem.
The corticobulbar tract innervates cranial motor nuclei contralaterally with the exception of the lower facial nucleus which is innervated bilaterally(bilateral cortical representation, where in UMNL, upper motor neuron lesions, the frontalis and orbicularis oculi muscles are spared). Among those nuclei that are bilaterally innervated a slightly stronger connection contralaterally than ipisilaterally is observed.
[edit] External links
