A second-order Cyc collection and a specialization of type of organism constituent. Each instance of internal animal body region type is a specialization of region on an animal's body whose instances are, under normal circumstances, located completely within (i.e. In Cont Completely) the outer surface of an animal. Instances include heart, brain, and bone. Non-instances include head, wing,and upper body human, which are instances of external animal body region type (q.v.).