The major motor tracts from the cerebrum (eg,
corticospinal and corticobulbar tracts) travel in the ventral aspect of the
brainstem (blue lines) while the ascending reticular activating system is
located more rostrally, in the tegmentum (green shading and dashed arrows). Brainstem insults
such as ischemic stroke or hemorrhage of the pontine base that spare the
tegmentum can produce profound bulbar and limb weakness with retained consciousness
due to this somatotopic organization of brainstem tracts.
