simtk.org

Hi,

I am just starting out with opensim for my PhD research.
I am trying to build a entire arm simulation to measure muscle torque for various movements
For certain muscles like Abductor Pollicis, i require the muscle to have multiple end points or increase the width of the muscle.
I tried increasing the scale factor in the muscle but, i was not able to increase the width of the muscle.
Please let me know if it is possible to increase the width of a muscle and also divide/add multiple end points to a single muscle.
I have attached the image of the muscle that I have created using opensim (opensim_model.png) and also the original muscle (original_muscle.png).
Looking forward to hearing from you soon..

Thank you.

Hi Yokhesh,

You might benefit from examining some of the lower limb models to see how this has been done with larger muscles. I believe for muscles like the gluteus maximus (which have wider spanning attachment points) they are split into different components (e.g. anterior, middle, posterior) by effectively modelling them as three separate muscles.

I'd also be interested in any advice stemming from this question, but more so around the idea of 'splitting' muscles. In certain surgeries muscles are 'split' and reattached in a different manner, and I'd be interested to know if anyone had experience with this and how it could be modelled (e.g. if you split a muscle into two components do you half the strength for each, do things like optimal fiber length stay the same etc.).

Aaron

Hi,

Thank you for the response.
Like you mentioned, I was able to build the corresponding muscle using the two or more muscle fibers combined.
Thank you..

Hi Yokhesh,
I just came across your post and would like to ask how you combined two segments into one muscle. I wish to represent the rectus femoris muscle using two line segments instead of one, which is the case in most of the lower limb models in OpenSIM. I have already tried what Aaron suggested could be tried i.e. splitting max isometric force but keeping the lengths same but it does not seem to work.
Your help will be really appreciated.

Regards,
Shivangi