All the axons of neurons that relay signals between the forebrain, cerebellum, and spinal cord pass through the brainstem.Running through the core of the brainstem and consisting of loosely arranged neuron cell bodies intermingled with bundles of axons, is the reticular formation, the one part of the brain absolutely essential for life.It receives and integrates input from all regions of the CNS and processes a great deal of neural information. The reticular formation is involved in motor functions, cardiovascular and respiratory control, and the mechanisms that regulate sleep and wakefulness and that focus attention.