The term area 33 refers to a narrow band of thin cortex in the anterior cingulate gyrus at its junction with the corpus callosum. In the human, it is located in the depth of the callosal sulcus.It's outer boundary is area 24. Equivalent to area 33 of Brodmann, it has three parts: area 33o in anterior cingulate cortex, area a33' in anterior midcingulate cortex, and area p33' in posterior midcingulate cortex. In the rat it is found only in anterior cingulate cortex and is not subdivided ( Vogt-2013 ). It is not found in the macaque or the mouse ( Vogt-2013; Vogt-2016 ).