Department of Defense Medical Examination Review Board
In the United States, this is the agency responsible for evaluating the physical and mental condition of members of the military. All members, including members of the various ROTC programs and at the academies.
The way I first learned about this agency -- and my first and only interaction with it -- was in high school. After my congressman nominated me to the Air Force Academy, I had to drive from my house in Los Angeles to March Air Force Base in Riverside, California for a physical examination. It was a real comprehensive examination that introduced me to a real disturbing detail about medical examinations in the military: some official has to watch you pee into a cup, and sign an affidavit that the urine submitted for review is yours. It's hard to whip out your dick and pee into a cup with some burly sergeant looking over your shoulder. (Unless you like that sort of thing...but I don't.)
Once they had my height and weight measurements, evaluations of my hearing and vision capabilities, several vials of blood and urine, and some basic numbers like my blood pressure and pulse combined into a folder with the rest of my medical history, all my medical information was shipped off to DoDMERB for review. They had final say on whether I'd be flight qualified, commission qualified, or disqualified.