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Brainstem
The midbrain (mesencephalon), bridge (pons), and medulla together constitute the brainstem. It can be considered one of the phylogenetically oldest parts of the human brain. Several main functions of the brainstem can be distinguished. First, all peripheral information (ascending pathways) to the cerebrum or cerebellum has to pass through the brainstem. Likewise, all descending pathways (mostly from the upper motor neurons) either have to pass through the brainstem or originate in its nuclei to connect to the spinal cord. Furthermore, the brainstem has integrative functions involved in cardiovascular control, pain sensitivity, alertness, and consciousness. Due to this crucial integrative nature of the brainstem, damage to this organ is followed by symptoms such as visual distur bance, changes in sensation, problems in coordinating movement, and hearing ...