Why is it that when a limb is amputated further from the extremity, for example near the shoulder rather than at the wrist for an arm, the reattachment of this limb is more complex and the reattached limb is often less functional and usable?
and is there a difference in the processes when the bone is smashed vs when the cut is clean ?
and what “less functional” mean ? (less sensations ? )
and finally why is a smashed bone in a limb curable and don’t lead to amputation , but a cut limb is often considered as lost ?
In: Biology
Your fine motor skills are controlled by lots and lots of really tiny nerves. They start out at your shoulder or your hips as big trunks of nerves, and then get down to really fine ones at your extremities.
When the bone is smashed, the soft tissue and nerves around it are mostly intact around the bone, so, once we stabilize the bones and help them grow back together, your body can work around whatever small damage there is.
When the limb is actually cut through, surgeons have to attach tiny nerve to tiny nerve. At the extremities, this is difficult, but not impossible — the nerves for your thumb are on the inside of your wrists, and the nerves for your pinky are on the outside. But if your arm gets severed at the shoulder, you’ve just got a big bundle of nerves and the surgeon isn’t sure what line goes to what finger, so they have to guess. The human body and brain are amazing, and with laborious physical therapy (PT) you can get some of it back. But it’s not nearly as good as if we hook your thumb nerves to your thumb and your pinky nerves to your pinky, and not the reverse.
ETA: “Less functional” means that when you feel it in your pinky, it might have been from touching your thumb. Also, when you try to move your pinky, the nerves might *go* to your thumb and your thumb gets the instruction. Your body and brain can eventually learn to overcome some of this, but it’s far from perfect. Better than just completely severed, but never as good as it was.
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