Course and distribution of facial corticobulbar tract fibres in the lower brain stem goes into some of the details .-- JWSchmidt 16 : 25, 3 November 2007 ( UTC)
12.
In contrast, pseudobulbar palsy describes impairment of function of cranial nerves IX-XII due to " upper motor neuron " lesions of the corticobulbar tracts in the mid-pons.
13.
Another important finding is a " false localizing sign ", the so-called Kernohan's notch, which results from compression of the contralateral cerebral crus containing descending corticobulbar tract fibers.
14.
The condition is usually caused by the damage ( bilateral degeneration ) to the neurons of the brain stem, specifically to the corticobulbar tract ( upper motor neuron tract to cranial nerve motor nuclei ).
15.
If the " corticobulbar tract " is damaged on only one side, then only the lower face will be affected, however if there is involvement of both the left and right tracts, then the result is pseudobulbar palsy.
16.
Thus, lesions of the corticobulbar tract between the cerebral cortex and pons and the facial motor nucleus destroy or reduce input to the ventral division, but ipsilateral input ( i . e . from the same side ) to the dorsal division is retained.
17.
Signals for the voluntary movement of stylopharyngeus muscle originate in the pre-motor and motor cortex ( in association with other cortical areas ) and pass via the corticobulbar tract in the genu of the internal capsule to synapse bilaterally on the ambiguus nuclei in the medulla.
18.
The corticonuclear tract is so named because it connects the cerebral cortex to cranial nerve nuclei . ( The corticonuclear tract is also called the " corticobulbar tract ", as the brainstem is sometimes called the " bulb " of the brain . ) It is via this pathway that upper motor neurons from the cortex descend from the cortex and synapse on ?-MNs of the brainstem.
