A method is disclosed in this publication for modeling different internal structures of a head, such as different parts of the brain, the method comprising the step of determining the location of the internal structures, such as the different cerebral parts, of at least one first head in a three-dimensional space by techniques such as magnetic resonance imaging or computer-aided tomography. According to the invention, the external dimensions of at least one second head are determined, and the location data of the internal structures of the first head are scaled in a three-dimensional space to correlate with the external dimensions of the second head, whereby the location data of the internal structures of the second head also become modeled without the need for anatomical images of the second head.