Get related tables in SQL Server

SELECT 
    C.Constraint_Name
    ,[FROM] = PK.TABLE_NAME + '.' + PT.COLUMN_NAME
    ,[To] = FK.TABLE_NAME + '.' + CU.COLUMN_NAME

FROM 
    INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C 
    INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK 
        ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME 
    INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK 
        ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME 
    INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU 
        ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME 
    INNER JOIN 
    ( 
        SELECT 
            i1.TABLE_NAME, i2.COLUMN_NAME 
        FROM 
            INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1 
            INNER JOIN 
            INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2 
            ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME 
            WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY' 
    ) PT 
    ON PT.TABLE_NAME = PK.TABLE_NAME 
WHERE PK.TABLE_Name = 'Usuarios'

Source
http://stackoverflow.com/questions/3321055/get-list-of-dependent-tables-sql-server-2005