Despite its name, internal medicine isn't just about treating internal organs: Doctors who specialize in internal medicine, also called internists, are actually specially trained to prevent and treat diseases and ailments that affect adults.
These specialists are valuable to the Army Medical Corps because they know what to look for based on a soldier's age. Their combination of general practitioner/family practice training and internal medicine specialty helps them understand what to expect at certain age brackets, which may help distinguish injury from disease, for example.
The internal medicine physician has a challenging job. On his Web site, Dr. Robert M. Centor writes, "Internal medicine deals with the most complex patients and most complex situations. Internists handle complex comprehensive care … Internal medicine is rarely 'run-of-the-mill'" [source: Centor].