Spine model

Hi, Anyboy

I am struggling to modify the existing model to fit to my demand so better get a help from you.

I’d like make a thoraco-lumbar spine model. I would like to include all muscles attaching to this area. Spine repository was fairly enough but it does not include latissimus dorsi and it is in Arm part.

Could you make a spine model including latissimus dorsi and other upper-extremity segments as dummies fixing each part with rigid joints (stdjoint) so there will be no need of muscle. I need this dummy parts for scaling parametric study later.

Thanks

Hi

I think the best way to do this would be simply to use a model with the arm muscles and then add AnyReac forces to all the arms joints. The body model named SpineTwoArms should be useful.

I would advice to exclude the arm muscles not needed since it will make the model run faster.

Best regards
Søren, AnyBody Support

Thanks Soren,

Could you explain more of AnyReac forces? Adding these change the joint constraint? I was already playing with SpineTwoAarms model. However, the results were varied according to the set of muscles and at some point it could not find the solutions (definitely) when the joints were not changed. I think just removing muscles may not be enough to get reasonable results. That’s why I would like to change the joint to fixed then there may be minimum effect of exempting arm and shoulder muscles.
If AnyReac forces are added, these kinds of problems will be resolved?

I tried to changed the all joints around arm and shoulder to fixed joint(stdjoint) but many things are cross-linked so keep causing other errors.

After finding the muscle forces in Anybody and those will be used as input for FE analysis. I would like to make the Anybody model as close as it in FE model.

In summary, what I wanted to do is

  1. Adding latissimus dorsi(in armshoulder part) to spine part.
  2. Fix the arm and shoulder joints.
  3. Don’t need any results according to the arm and shoulder part.
    Would you give some tips for carrying out this?

Thanks

Hi

AnyReacForce is a way of adding a reaction without of prescribing the motion. In AnyBody reaction and motion can be separated completely.

In this case, if you have the model running kinematically i guess you have, you should simply switch on by setting the Reaction.Type ={On} in the drivers for the arms, if you do this for all the arms joints the muscle will be unloaded. in case you have no drivers for the arms please look in the JointAndDrivers.any file in the FreePostureModel it is a good place to find all the drivers. Setting these reaction to on will do exactly the same things as adding an AnyReacFroce to the same joints, it is like having an engine on the free dof in the joint.

Adding AnyStdJoints will not be so easy, and the setup described above will effectively do the same all dof will be carried, but in contrast to the standard joint you still have freedom to set the joint angles, but all reactions will be carried.

After having added the drivers and switched on the reactions you will need to modify the muscles in the arm, this is done in the file Arm/Mus.any.

Hope this helps you move on, otherwise please write again.

Best regards
Søren, AnyBody Support

Thanks, soren

In terms of Reaction.Type, I already tried but there was an error saying “Muscle recruitment analysis failed” and that’s why I was changing the joints to stdjoints. I changed all drivers at that time but I will check one by one this time and see if there is any mistake I made.

Hi

Ok sounds good, please write again if it does not work out.

Best regards
Søren, AnyBody Support

Thanks soren,

I could find some variables and files causing the errors and after removing them, my model works fine now. Btw, I got another question. I am looking into the muscle files and the muscle names are a bit difficult to come up with indicating muscles. Do you have any reference of full muscle names? Thanks

Hi,

In the top of the file “SegmentsLumbar.any” you can find a list of abbreviations.

Greetings, Mark

Thanks a lot Mark,

How did you name those abbreviations, by yourself or followed the references?

Well, both. As far as I remember we have been inspired a lot by the work of Bogduk mostly in relation to the multifidi. There are so many fascicles in the model, so it is important to have a logical naming sytem. So I hope you can see the system in it.

Mark