Call 1-800-PRINCESS and press option 2 to get the reservations department and ask your question there. I doubt that there are medical facilities or medical staff anywhere along the land portion of your itinerary that are directly connected with Princess, but if there is a Princess tour guide that stays with your group, that person would assist you in getting to the proper medical facilities if you have taken out Princess' own medical insurance. Otherwise, they'll probably provide you with a phone number and you'll be on your own.
Onboard, Princess has excellent medical facilities.
You could also go to http://www.princess.com
and type in appropriate keywords into their search engine, which is in the upper right-hand corner.