I have a question about the new abdominal model in AMMR4-beta.
As far as I understand it, the abdominal pressure is applied by the AnyRecruitedActuator class. To calculate the forces, the AnyKinVolumeCylMesh class is used, which measures the volume of the individual cavities. Where or on what exactly do these forces act?
Also, shouldn't the AnyRecruitedActuators normally only apply a force depending on the volume of the cavities and not on the activation of the transversus muscles?
However, as a test, I have set the muscle activity of transversus 2 to 100 % in the standing model using the AnyMuscleActivityBound class, without changing the volume of the cavities using kinematics.
This leads to an increase in the force of the actuators. Where is the dependency between the transversus muscles and the actuators defined in the script?
I would be very pleased to receive a short answer.
The Recruited Actuators are acting on the volumes, and it can directly act on them, because they are measures. And the actuators can create any amount of pressure that is needed.
The Rectus, Obliquus, and Transversus muscles have connections to the abdominal layers and can push on the volumes and balance the pressure from the front side. Of course Transversus is the most effective one to pushing on volumes. Diaphragm muscles also balance the pressure from the top and transfer the pressure force to the lower ribcage
Normally I should be able to adjust the volume by integrating additional nodes so that I can apply the forces of the abdominal pressure specifically to other structures, right?
The answer is yes. So you can integrate more nodes to the abdominal volumes and the pressure will affect those segments. But I normally do not advise to change the abdominal nodes
What do you mean by "other structures"? Is it an external segment?
If so, you can make a connection to the base-anterior segment of the layers and the pressure can make a force to the external segment. So you do not need to go into details and change the volume nodes.
I would like to model the pelvic floor muscles in detail. Therefore, my idea would be to define the pelvic floor muscles in the model via muscle via points. I would have created a segment for each via point. I would then have adjusted the volume of the lower cavity so that the abdominal pressure acts directly on the segments of the via points of the pelvic floor muscles. Do you think that could work?
OK, that is a nice improvement to the model!
You will need an additional segment. There are multiple layers in the pelvis, so you can utilize nodes from the lower layers (perhaps one or two lower layers) and allocate them to this new segment. This way, the pressure will be distributed across the new segment and the pelvis.
A straightforward (and possibly sufficient) implementation could involve an inferosuperior prismatic joint connecting the new segment to the pelvis. The pelvic floor muscles would then balance the pressure applied to the new segment.
Another consideration is the potential need to divide the pelvis into right and left segments. However, this is not a simple task, as it involves relocating nodes across layers to the right and left segments, and the pelvic floor muscles must balance these segments while accounting for lateral pressure forces on the right and left pelvic segments.
