Indicator List for the External/Internal Typology

by R.Schleip (July 1997)

Jan Sultan, the originator of the external/internal typology, has updated his description of how to best determine the structural types. He now gives the following list of six indicators of whether a person is an external or an internal type. These six indicators should be seen to be in a sequential order (with the first one as the most important, and so on).

1.    Shape of cranium in terms of a-p length (antero-posterior) versus transverse width (long and narrow: internal; short and wide/broad: external).

2.    Shape of occiput. Internal: prominent occiput ("occipital shelf"). External: flat occiput

3.    Spinal curves. Overall amplitude of spinal lordotic & kyphotic curvatures. Strong curves: internal. Flat curves: external.

4.    Pelvis shape. Seen from backside: pear shape (wide tubs) = internal. Apple shape (narrow tubs) = external.

5.    Femur rotation. Best seen in movement rather than in standing. If femur relatively more medial rotated = internal. Clear lateral rotation: external

6.    Legs. Internal type: genu varus pattern plus long flexible arches. External type: genu valgus pattern plus high fixed arch (or bear paw).