One option might be to use a tab control with one tab panel for each of your 10 locations. Instead of selecting a site from a drop down, you'd click a tab label for that site.
Another option would be to use one Details table instead of 10, with a field that identifies the location. This may require 40 fields in place of the 20, you might need 20 calculation fields that use the value in the location field to produce text that serves as the label for your 20 original data fields. Whether that will work for you or not will depend on the type of data you need to collect for each of your 10 body locations.
Other options--such as script triggers that change layouts that appear nearly the same except for the location specific portion of the layout--creating the illusion of an "adaptive layout" is also possible.
In theory, you could even set up a 10 panel slider (In FileMaker 13 or newer only) and a script triggered from what you select as a location can use go to object to bring up the slider panel specific to that body location.
Thanks a lot Phil. Very helpful and much appreciated.