Whenever any supernatural story, fictional or true, involves body parts, it's always a skull, or a mummified head or hand. We never hear of the 'Phantom Pelvis' or 'Evil Elbow'. Always a head or a hand. Where is the 'Foot of Fear' or the 'Tibia of Terror'? Whatever happened to the 'Duodenum of Despair'?
No, always a head or a hand. So there must be logical reason for this, surely?
Yes, there is. Starting in 1940, Dr. Wilder Graves Penfield mapped the parts of the brain that deal with various sensory and motor functions of the body. From there, he constructed a diagram, later made into models, of 'Penfield's Homunculus'.
This is a representation of how the brain 'sees' the body. Obviously, the sensory organs around the face are highly represented. Most of the body is ignored by the brain, but it is notable that the hands are enormous.
The whole of the trunk, the lungs, heart, intestines etc play only a small part in the brain's 'body map'. It is mostly concerned with the sensory apparatus of the head, and those useful appendages, the hands.
In that case, a disembodied consciousness is unlikely to pay much attention to its ex-ribcage, but might be deeply concerned about those parts it regarded as important while brain-bound, in life.
There is also the alternative explanation, that we, the living, set more store by those parts of the body and are therefore more likely to consider them the important parts of the corpse. For writers, the decision to use a head or a hand in their story might be an unconscious reflection of their own brain's body image. That works to explain the fiction aspect.
There remains the real-life reports of screaming skulls, and the preoccupation of both the occult and religion with hands, for example here and here. The Lancashire witches used to collect skulls and fingers from corpses, and the hand of a hanged man was allegedly used in witchcraft to create the Hand of Glory. These are hardly scratching the surface of possible examples where, throughout history, heads and hands have been elevated in importance above all other body parts.
It's always been about heads and hands, throughout history. Perhaps Penfield's Homunculus represents more than simply a neurological map.
Perhaps heads and hands are even more important than we think.