An important point that I did not include in the OP is the fact that the autopsy evidence shows two separate, disconnected wound paths in the brain, i.e., the subcortical and cortical damage to JFK's brain. There is no wound path or fragment trail between these two wound paths—in other words, these are two separate, unconnected wound paths. The cortical damage is near the very top of the skull; it is close to the high fragment trail and is on the outer (or cortical) surface of the brain. The subcortical wound path is nearly 2 inches below the cortical damage and spans the length of the brain from front to back. The first expert to note these two separate wound paths was Dr. Joseph Riley, a neuroscientist who specialized in neuroanatomy.
British researcher Martin Hay has said the following on this issue:
Since you have identified him as a research and not an expert in forensic pathology, I am going to assume he is not the latter. That means he is no more qualified to discuss the medical evidence than you or I.