The most commonly misunderstood detail of a deer’s anatomy is the vertical bulge or crease seen directly above a deer’s front leg. This is caused by the triceps muscle. Many bowhunters mistakenly assume that this bulge is caused by the presence of an underlying bone structure, which must be avoided.
The truth is, when an animal is broadside, the vital area is well exposed at this point. As you can see on the cutaway model, the Humerus bone runs forward from where it joins with the front leg, leaving an unobstructed path to the vitals.
Instead of a spot to avoid, the rear edge of this bulge, often called the crease, is an ideal aiming point for a broadside shot. When taking a quartering shot, the aiming point must be farther back in order to center the vital area.