If this is so you can list them in your PS, its a bit of a waste of time/space. You haven't got space for this and you wont be able to say anything new about them that the admissions team haven't read a thousand times before.
If its more 'getting an idea of what to expect about the job' or 'what sort of stuff will I have to do as a Med student' then a good beginners guide is 'Medicine at a Glance' by Patrick Davey (Amazon or cheaper 2nd hand copies on Ebay).