The Pirate Queen’s son finds a merman

(AU of Iris and Lillium from CTC)

Meta: Prosthetic Sensation

Next in my super long tedious posts…

Let’s talk about sensation. The first thing to understand is that sensation isn’t just a cute little feature but is kinda vital for function. The second thing is our modern prosthetics by and large do not give sensory feedback - this is compensated for by other senses, usually vision.

The third thing is - adding any new feature is expensive and cumbersome, so let’s consider that Hydra would only build in what’s absolutely necessary.

As you can see, there is actually a lot of different senses that our body perceives and transmits to the brain, so let’s break this down and talk about each section in relation to Bucky.

Tactile

Under this heading, we have light touch (the light brushing of a tissue across the skin) and pressure. Unfortunately we never see Bucky gently brush against something with his metal hand, so we don’t know whether it has light touch sensation. Is it useful? It’s fantastic for small dexterous tasks, like playing a string instrument for example, or working out the different textures of objects, but for a Hydra assassin? Probably not.

I just thought this picture is cute because look at that fumble. I know Seb often shoots scenes with his fingertips exposed, but this looks accurate for someone who doesn’t have light touch discrimination (which Seb won’t have if he’s wearing the full metal arm) and is struggling to flip the cover open then tries it with his right hand but has never done it that way and in the end just gave up and flipped it around.

Pressure, on the other hand, is really the crux here. Without pressure sense, you have no idea how hard you’re holding something. It lets you hit the happy medium between dropping an egg (because you’re not holding on hard enough) and crushing an egg (oops).

Bucky can do this - the light press of a button without crushing the whole console, then increasing the pressure on that device to a point where it’s strong enough to pull Sam from the sky but NOT crush it:

To this - grabbing into the handle, not snapping it, adjusting his grip strength (pressure) in reaction to the movement and torque and angle, all while steadying it in a way he can set it back on the ground and mount:

You can’t do this level of finesse without being acutely aware of how much pressure you’re exerting, because no matter how much you try, your vision can’t compensate that well.

Proprioception

Ah, the magic sensation of knowing where your joints are, how hard you’re working your muscles and where bits of your body is in relation to the rest of you and your surroundings. If you can close your eyes and touch your face, that’s your proprioception there hard at work. Since most of our regular prostheses don’t have this feature, most amputees have to use their vision: ie, they have to keep their eyes on their prosthesis (esp for upper limb) to grasp and release at the right place.

But look at what Bucky can do - he’s manoeuvering a small delicate object out of his field of vision - he has awareness of where his shoulder, elbow, wrist and fingers are in relation to his waist, he is able to gently wriggle it out (pressure sense!) and feel it drop into his hand, then bring it around all without looking.

Particularly with Bucky being a high level amputation (ie nothing below the shoulder), there is absolutely nothing there (no upper limb stump or anything) to help him even guess where his prosthesis is. He definitely has proprioception inbuilt into the prosthesis and it’s connected to his brain, somehow.

Pain

Before we discuss pain, we need to understand the function of pain. It’s not there to upset or inconvenience us. Pain is a warning system to tell us of impending damage. It is an unpleasant sensation because it forces us to swiftly react to the danger.

Now, if you want to create the perfect soldier who will soldier on, if you will, through injuries and accomplish the mission at any cost necessary, you'd probably want to take away that warning system. The pathway for pain is primitive and instinctive, so you don’t want a situation where the soldier avoids the mission because of fear of pain/injury. You want the pain to be something you can use to control him, and not a distraction from his missions. I wouldn’t be surprised if, in addition to lack of pain from the prosthesis, his mental conditioning also reduces his reaction to pain during missions.

But even outside of the WS mode, Bucky still abuses his arm, so I doubt he has pain built into it. Now - phantom pain is another matter which will require me to do more research, so will talk about that another time (maybe).

What it means

Bucky’s prosthesis likely has pressure and proprioception built in, but NOT light touch or pain - and probably not temperature sense either. Remember with each mode you want to add, you have to add components and weight onto the prosthesis, making it unwieldy.

But you know what’s always surprised me? This:

The modern prosthetic grip is weaker than a human power grip (according to this anyway but technology may have moved on). But remember this is the arm that Bucky used to stop his 10m drop by catching onto a handrail and it didn't break the grip. He's also used it to smash concrete, punch through walls and pull a steering wheel out so Hydra's definitely made it much stronger than a normal human grip.

Now, the two times he’s choked Steve and the one time each with Sam and Nat, he’s managed to not crush their trachea or even press on their carotids hard enough for them to lose consciousness.

Compare here with the Hydra scientist, whose eyes are rolling back into his head because he's not getting blood to his brain.

So we know the Winter Soldier has the grip strength, we know he has the pressure sense to know how hard to go, and we know he knows the technicalities of choking someone by hand. But he doesn't. Additionally, each time he's used that choke grip as Bucky (against T'Challa, Zemo, and random guy in Madripoor), it's a restraining measure rather than an actual killing/injuring move.

So, my question for the two people who read down this far - did they depower his metal arm because of what happened to the Hydra scientist? Does the Winter Soldier only use this as a restraining move? Or is Bucky in there, fighting to stop himself from killing people with the chokehold because of the way he was commanded to kill Maria Stark?



phantom limb

“The US military dropped me behind the line to go deal with him. I took half that Metal arm in that fight in Goyang…”

I just want to see more of Isaiah, especially him tearing off that arm and throwing it into a Wall. Always use reference. The first sketch I did was so bad I had to redo it… I am glad I used reference.