It sounds like there were two main incisions (surgical-like cuts) one on each side of the neck.
The right side was approximately 2 1/2 inches long lengthwise across the neck, and it was almost 2 inches deep into the neck, if I read that right?
The report seems a little bit poorly written to me too.
The left side had a longer approximately 3 1/2 inch lengthwise incision cut slanted across the neck, and it went about 1 1/2 inches deep.
There appears there are also some superficial incisions or cuts noted on the left side of the neck too, with a separate maybe slightly deep (not measured) incision on this same left side of the neck as well. Those are common findings from what I understand, as people are attempting something like this to have pre-cuts on one side like that prior to as they go forth to do the main cuts.