By far the most common treatment I have seen on Whitney and JMT is for blisters. Probably as many treatments for blisters as everything else combined. I go through a lot of Second Skin and tape, invariably treating others. Next is minor abrasions and lacerations. Cloth bandaids or small pads and really good stretchy cloth tape - never plastic for either. Then sprains, requiring triangle bandage if the boot has not been removed (preferred) or ace wrap/tape if light shoes are involved or boot has already been removed.
After that, things get serious. Major bleeding, broken bones: lots of pads are fairly light and small splints are fairly convenient. For large bones maybe splints can be improvised. Then there is really serious trauma, lighting strike, heart or stroke, very rare but it happens. Almost impossible to justify the weight of what it takes to be prepared for that, except for shock and hypothermia. Space blanket, source of heat, the rest can be improvised from what you already have: sleeping bag, hot water in the bottle etc. Should be prepared to do an evaluation: penlight, watch, there may be some small electronic BP gizmo that I am not aware of, but complete basic life support stuff is pretty much out of the question. CPR in the backcountry is almost always futile, in any event, unless you have a sat phone and can get an ALS unit on the scene in an hour