I need to know how much tension, roughly, a human arm can withstand before being torn out of its socket and becoming detached from the rest of the body. Any medical background or source of information would be appreciated, as i would like to be able to quote evidence.
It is difficult to find such information when needed.
The actual question i am trying to answer is, “If you tied yourself to a bridge by your arm, and threw yourself off the bridge, would your arm be ripped off?”
Given that the bridge is the Golden Gate, giving yourself a 81m fall, during which time you would attain an approximate velocity of 31m/s during a 4.2 second fall, with wind resistance.
The stretch of the rope would be negligible compared to the arm extension, i would assume. I am also assuming that the average mass of a falling individual is 70kg.
Any other relevant factors for consideration will be appreciated.
Uh, what exactly are your plans here? Maybe if we had more specifics, we might be able to help you better…
Jill
Its purely a theoretical exercise. Idle speculation.
There will be a fairly significant difference in force required based on exactly how you plan to hold your arm when you jump. If you jump with your arm fully extended, it will take less force than if you jump with your arm bent and use your muscles as a “shock absorber”, reducing the impulse of force upon the joint itself.
What’s the matter, Gollum? Biting fingers off not enough for you?
Just after the actual strength of the shoulder socket, as im not quite sadistic enough to test for myself. The rest can be figured out.
If I had me some hobbits though…
“How disarming,” said Captain Hook, off-handedly.
I think it’s most likely that your hand would slip out of the loop, possibly losing some flesh in the process, maybe the hand would come off.
Assume then, that the arm is well secured, perhaps with a leather thong or well tied knot. Unless someone has other information that suggests the flesh would be stripped from the bone before the arm is dislocated?
Does anyone know? of 250 views, which would mean at least 100 people, no one has any stats, or places i could start looking? Surely the military or someone has put fresh cadavers into tension and observed the results?
Well possibly try the Darwin Awards website. I believe they carried the story of a guy who tried a bungee jump off a bridge using an extension cord. His foot came off.
Get a whole chicken (completely thawed) at the supermarket. Attach a fish scale securely to the free end of the drumstick and pull hard until the shoulder joint comes apart. Don’t go easy on the chicken - you want to simulate the high-rate jerking load that would occur in the scenario you’re describing. Write down the highest force attained before the joint gave way (have a friend read the weight off the scale because you won’t have time to). Then multiply that number by the ratio (weight of an average human being/weight of the chicken you pulled apart) to the two-thirds power. Repeat with the other drumstick and average the two numbers. That will give you the tensile strength of a human shoulder joint certainly within an order of magnitude, which is probably all you need. I’m guessing the human shoulder is not nearly strong enough to withstand what you’re describing. Peoples’ arms get pulled off all the time in farm machinery without getting their entire bodies pulled into the machine, so the strength of the shoulder joint can’t be that high.
Then, cut the chicken into pieces and dredge in corn meal. Make a mixture of half a teaspoon of ground black pepper, half a teaspoon of salt, and a cup of freshly grated bread crumbs. Beat an egg in some milk, and coat the chicken pieces with the egg wash before dredging in the bread crumb mixture. Pan fry and serve with ice cold sweet tea. Enjoy!
<< I believe they carried the story of a guy who tried a bungee jump off a bridge using an extension cord. His foot came off. >.
There was also the guy who jumped off a bridge holding a parakeet – he was trying to do budgie-jumping.
Come on, am I the only one who got this? Good one, QM!!
I don’t believe that the shoulder joint is ‘ball in socket’ and is held in place, for the most part, by muscles. I know people whose arms will pop out if they lift anything heavier than a dictionary.
Long and short of it - you are not going to be able to give the detatching force a number without a very painful experiment.
City Gent, Your idea has merit. Still, i am not sure if a chicken is a very good analogy for a human, even if it were scaled up. I imagine i would get a number within an order of magnitude, but i would like better if its available. Maybe if cloning were a bit more advanced i could get a test person made up. There are too many differences in muscle type and ligament attachment, i guess, between a chicken and a person for any hope of accuracy. Something mammalian might work as a substitute. Monkeys are similar in shape, but stronger and tougher for their weight than modern man, so i would still have to scale the result back. Also, im not up for collecting dead monkeys to experiment on.Ideally I would want something recently dead, so its muscles retain elasticity.
Was ye olde drawing and quatering done with bonds at the wrist, or was the arm better secured?
Farm equipment dismemberment is not really close enough to compare, unless someone has a specific example where the arm was torn out of the joint in a consistant direction.
Will try the Darwin Awards, but i hold little hope.
Feels like a ball and socket joint to me.
CK Dexter Haven, just can’t stop punning can you?
People who study biomechanics might have data on this. If you have access to a campus library, you might try to look up stuff there (unless anyone has suggestions for searching online). I know they study things similar to this–one time on a tour of Mayo clinic I saw some people work on a cadaver’s elbow joint. They were trying to test mechanical strength and see how it varied after several ligaments/tendons/muscles were severed.
I doubt that you might be able to find the “tensile strength of the shoulder”-type stuff. But, you can probably find data on the tensile strengths of the various tendons, ligaments and muscles which attach the humerus to the shoulder girdle.
The appropriate muscles (those running from the shoulder girdle/torso to the upper arm) are:
[ul]
[li] Pectoralis major[/li][li] Teres major[/li][li] Triceps[/li][li] Coracobrachialis[/li][li] Latissimus dorsi[/li][li] Deltoid[/li][li] Subscapularis[/li][li] Supraspinatus[/li][/ul]
I would guess that, based on size, the major ones to worry about would be the Pectoralis major, Latissimus dorsi, and Deltoid, and Subscapularis; the others, being thinner, have thinner tendons, and would likely snap sooner then the larger tendons/muscles). The muscles of the rotator cuff - the Subscapularis, Supraspinatus, Infraspinatus and Teres major - will likely will be important as well.
The appropriate ligaments are:
[ul]
[li] Trapezoid[/li][li] Conoid[/li][li] Superior transverse scapular[/li][li] Coraco-acromial[/li][li] Coracohumeral[/li][li] Transverse humeral[/li][li] Middle glenohumeral[/li][/ul]
You may have better luck finding the collective tensile strength of these ligaments, rather than individual ones.
Just a bit of 'armless fun, eh what?
I remember seeing on a site somewhere about a man having his arm torn off in a tug-of-war contest and they had photos too. I can’t pinpoint the source at this moment though.