There are some websites that say shooting deer with a rifle in the Autonomic Plexus drops them fast. Say What? But it is not where the center mass of heart and lungs are exactly. Really? Ok so what is the autonomic plexus? 

It is a point just forward of the front leg where there is a nerve and artery junction entering the lungs. I have learned that it is sometimes called the hilar zone.                   

image taken from www.ballisticstudies.com

So why am I telling you this? Honestly, after 50+ years of hunting deer, I have never used this point of aim on a whitetail or an ungulate with rifle or bow. Too much chance to miss vitals, I think. I aim rearward three or four inches of the above crosshairs striking the upper heart arteries and lungs. Below, this 50 cal muzzleloader shot was two inches high but he will never tell. He collapsed on the shot.

There are slightly differing point of aim for bow vs rifle.

Where shooting with bow slightly behind the front leg on a broadside shot to clip the heart and center punch the lungs. On rifle, there are many other professionals that teach to shoot on the front shoulder or just behind it on the lower 3rd of the body if on the ground. Or about three inches higher if shooting from a 15 ft high tree stand.

The truth is, if the angle of the deer changes, so should your aim point as the deer quarters toward or away.

Visualizing the 3D anatomy of heart and lungs are essential to strike them with bullet or arrow. Thus the use of the autonomic plexus as an aim point is, in my estimation, a poor common aim point as it is seen best when broadside and requires precision shot placement. 

Bowhunter education, for example,  drives home the concept of visualizing the heart and lungs at different angles so your arrow may find them. Rifle hunting is much the same but is, at times, not covered as well educationally as in archery. Shoot for low center lungs, on the shoulder or just behind. What looks like the shoulder above the front leg is where the scapula and leg bones make a triangle shape that has no bone.  Some anatomic charts vary a bit but you get the picture.

Good Shooting!