The term alpha part of the gigantocellular reticular nucleus refers to one of two parts of the magnocellular reticular nucleus, the most ventral portion of the gigantocellular reticular nucleus in the medulla of the human ( Paxinos-2012 ), macaque ( Paxinos-2009a ), rat ( Paxinos-2009b ), and mouse ( Franklin-2008 ). The other is the ventral part of the gigantocellular reticular nucleus. Functionally the magnocellular reticular nucleus belongs to the reticular formation (functional) of the brainstem motor system ( Swanson-2004 ).