Been in the trenches watching One Piece and creating Oc's with my wife, more info under the cut
Vertebra (they/them) is a doctor for the Creature pirates, part of the Worst Generation (captain is RayRay that belongs to @garnetdawn !) They ate Dog-Dog No Mi model Cerberous* and come from an island of dog minks.
Alloy (she/they) is Strawhats ship engineer, working with weapons and small inventions. She is good friends with Usopp and Franky as they are an inventor trio. She has a friendly turned romantic relationship with Law during the alliance. She is also a childhood friend of RayRay and Eustass Kid!
*I made this OC before I learned that there is already this devil fruit in canon. Im still upset it was given to a SWORD but I dont care now I like my OC too much to change it.
Snappin necks is a really cool thing to do in an action movie, so I'm gonna break down how strong you need to be to do it.
"Breaking a neck" aka cervical dislocation, happens when the vertebra are rotated far enough that the vertebral canal is disrupted and the spinal cord is fucked. To do this, you gotta overpower some ligaments (which keep bones together), muscles, and tendons (holds muscles to bones). To keep it simple, we're gonna say the guy is on his knees in front of you, and has brain damage or something, so he's not really fighting back. You're gonna put one hand on his chin, and the other on the back of his neck. This will allow you to create torque, which will lead to cervical torsion, which will lead to cervical dislocation, and you know where we're going with this.
Okay, so what is torque? Torque is a specific type of force in which the force is applied to the end of an object, causing that object to rotate. An example of this is when someone uses a wrench. When force is applied to the end of the wrench, it causes the end around a nut to rotate. Most people can understand the concept that as your hands move further from the end of a wrench that is around a bolt, the easier it is to turn. This is because the force applied is multiplied by the length of the lever arm. The lever arm is the distance between the point of rotation and the force being applied. In this case, the lever arm is the distance between the chin and the spine. In most people, this distance is 15 cm.
How much force can the vertebra withstand? The minimum torque the vertebra can be subject to before dislocation is 14-17 Nm (Newton meters are the units of torque, because it is a force [Newton] applied from a distance [meters]). We can plug 17 Nm into our torque equation with the lever arm length, and we get ~120 N. Your bicep needs to produce 120 N of force when you curl a 26 lb weight. That's not very much, is it?
So back to the muscles. The main muscle that will resist your motion is the sternocleidomastoid muscle. This originates from the sternum and collar bone, and inserts onto the skull below the ear. Now, this muscle is not really that strong (who does neck exercises??). Working with any other neck muscles to resist the rotation, this probably puts opposite torque in at around 1.35 Nm. Plug everything back in (with our added torques), and we still only get the force (128 N) needed to curl a 29lb dumbbell. Huh, so your neck muscles really don't help you, do they?
"What about the mandible??" you say...well it's pretty strong actually. It requires about 125 lbs of force to dislocated it when acting in the direction we are, so the neck will dislocate first.
Even if you don't totally destroy the spinal cord, there's some really important crap in the cervical region (like the vertebral arteries and spinal nerves) that will totally kill you if they get messed up. There's the vertebral arteries, for one. You can break those and die of internal bleeding even if your spinal cord is fine.
Another note about where this will happen: you have seven cervical vertebra (C1-C7). C1 and C2 are pretty weird and close nit, so they're probably not going to give first. The greatest amount of flexion is between C4,C5,&C6. Also, because C7 is pretty sturdy in its attachment to the thoracic vertebra, C6 can also dislocate off of it easier. So I bet this dislocation will happen in the lower half of the neck.
Bottom line: if you can curl a 30lb dumbbell, you can probably generate the necessary force to break a grown man's neck.
Anyways, I could go on and on about this (I have a thirty-five page literature review I wrote over this topic), but I think my point has been made. Just one final thing: you probably can't do this irl, bc you need the perfect circumstances and the right technique. Oh well, stuff like this is probably best left to Chuck Norris and Arnold.
