What would it take for someone with an invincible head, neck and spine to die of fall damage?

Question

In my setting, characters are (mostly mildly) superhuman in various ways. One aspect of this is that, as long as they're alive, The entirety of their body from the neck up (flesh, bones muscle, teeth, brain and all) is completely indestructible, as is their entire spinal column and all tissue immediately connected to it. The hands (up to and including the wrists) and feet (up to and including the ankles) are also indestructible just like the head and neck (I don't expect this to be important to the question but I thought I'd say so anyway just in case).

The rest of the body is also more durable than that of a real-life human, but I'd like to ignore that for the time being and focus specifically on the effects of these parts of the body becoming indestructible, and how it relates to a specific method of trauma that's going to be happening a lot in my story: fall damage.

What with the head being the most vulnerable part of the body when it comes to blunt force trauma, I imagine making this part of the body completely invincible will radically alter what it would take for someone to die of falling from a great height, as well as what injuries they would succumb to, and how quickly. And since one of the main obstacles the heroes are going to have to deal with is a suburb where humans are subjected to sideways gravity, getting a better idea of what heights these people would have to fall from in order to take lethal damage, and what that lethal damage would look like, is going to be pretty important.

If the head, neck and spine are completely indestructible, what's the next part of the body most vulnerable to lethal damage from a fall, and what kind of a fall would it take to inflict it?

Answer 1

Deceleration injuries of the heart and aorta.

These are common injuries in falls and other impact trauma.

Fatal falls from a height: The use of mathematical models to estimate the height of fall from the injuries sustained

Interestingly, almost 50% showed a combination of head, thoracic and abdominal injuries, with severe or disruptive head injuries being found in approximately a third, and lacerations and ruptures of the heart and of the thoracic aorta in almost half, of all victims

The heart and aorta are fairly weighty, being full of blood, and have a propensity to tear or rupture on energetic impact. It was interesting that in this series out of Singapore these injuries were more common than fatal head trauma.

One could make a case that in the context of an invincible spine, these supers might be even more likely to die from aortic rupture. The spine is an excellent shock absorber. Suppose a person falls from a height and lands on his feet. There is a very good chance one or more leg bones will break. Suppose I stipulate that this person has unbreakable leg bones. Now landing on the feet is the equivalent of landing on a metal rod pointing up. The leg bones will traverse the non-invulnerable insides and this person will be badly hurt by his invulnerable leg bones.

Bottom line for a realistic world: invulvnerability limited to certain body parts could deflect stresses onto the remaining noninvulnerable parts. I used to wonder about that with Steve Austin; how does his pelvis and shoulder girdle withstand those forces transmitted from his bionic appendages? If you want that stuff better to have the world be selectively unrealistic..

Answer 2

I imagine your brain, even if invincible, still needs oxygen to, well, think. Oxygen is carried by blood. So there are two major failure modes:

• Your lungs stop extracting oxygen from the air. Blunt trauma from the fall might do it, but if your ribcage is not ivincible as well, rib puncturing your lungs should be enough without medical attention.
• Your blood stops circulating. Either your heart gives up (fall can literaly tear your heart off), or you suffer fatal blood loss - if enough of your bones shatter, chances to have an artery or a major vein punctured are high.

Your brain might continue being "alive", just without any electrochemical activity - i.e. less "life" than a deep coma. Unless there are chances of vat-growing your replacement body for a brain transplant (how do you sew invincible nerves, anyway?), people might as well bury you as irreversibly dead...

Answer 3

"...What's the next part of the body most vulnerable to lethal damage from a fall...?" All the rest of it!

True story, and please forgive the gory details: When I was a kid I saw what turned out to be the aftermath of someone committing suicide by jumping out the window of a tall building. The person had hit a pipe just before hitting the ground. The pipe was deeply dented. Again, sorry for the gruesome details, but I will never forget what that pipe looked like, and the thought of how much force it must have taken to dent it so badly.

The rest of your super powered persons body sounds like its still normal outside of the areas you specify. Even if he/she takes the hit on the invulnerable head, if the fall is from high enough, or they're thrown with enough force, the impact can still be enough to crush the body, pulverize organs, etc. etc.

But lets dial it back even further. You ever see those body slam moves the wrestling guys do? Even one of those could be enough to kill or badly incapacitate your guys, if down with enough force. Your guys basically have vulnerable torsos and a body slam mostly affects the torso.

In short, your invulnerable characters are still very much vulnerable. But I like that. It gives them a weakness that brings them down from the level of say a Superman. Even though they're invulnerable they can still be killed. This adds extra dimensions to your story.