The Area being Modelled is :-
Corporate Hierarchy

Here are the Specifications :-
Subject: Corporate Hierarchy
Question: 
I have four tables. Employee (EID,Name,Position, ReportsTo), Region(RID,RegionName), 
Branch(BID,BranchName) and Office(OID,OfficeName). 

A Consultant owns his office only, A branch manager owns his own branch and All offices 
inside his branch, and a Regional manager owns his own region and All branches and offices 
inside his region. Presdient and VP owns everything. 

The purpose of this hierarchy is that when a data security is applied on this structure, 
everyone see only the data that he owns. 

Can someone please tell me what should be the model of this hierarchy