This link from about.com has a cross section diagram of a hog's vitals.
In the link provided the rendering of the hog is anatomically incorrect in a number of ways. BUT, the central point....(aim closer to the shoulder) IS a valid point.
Thank you for helping to point that out. The reputation of wild/feral hogs for being "tough" is largely undeserved and is owing in no small part to poor shot placement (read too far back).
While those shots ultimately kill the animal, more often than not, the hog will run a long distance or require several "follow up" shots (usually similarly placed). The hunter is then left thinking "man these things can really soak up the lead"!
Any reasonable bullet/cartridge combo accurately placed in the neck will drop almost any hog....almost every time. IF circumstance permits, take that shot.