The reticular formation is a diffuse collection of

(D) All of the above # Reticular formation, the phylogenetically old reticular core of the brain, occupies the midventral portion of the medulla and midbrain.> It is primarily an anatomic area made up of various neural clusters and fibers with discrete functions.> It contains the cell bodies and fibers of many of the serotonergic, noradrenergic, and adrenergic systems.> It also contains many of the areas concerned with regulation of heart rate, blood pressure and respiration> The RAS is a complex polysynaptic pathway.