Scapula nodes

Hi

This question relates to scapula nodes and in particular the following section of text is copied from AAUHuman\Arm\Seg.any.

Could you please tell me how you determined the following nodes:

    AnyRefNode ts = {
      sRel = {-0.117455, -0.017693, 0.006280};
    };
    
    AnyRefNode ai = {
      sRel = {-0.130736, -0.130236, 0.006280};
    };
    
    AnyRefNode aa = {
      sRel = {0.022522, -0.017693, 0.006280};
    };

Were the numbers just determined by ‘guess and check’ identifying when the points visually were in the right place or do you have another means of determining the node locations?

I would like to add a wrapping surface to represent the lateral border of the scapula to prevent the infraspinatus muscle paths intersecting the scapula so will need to determine additional nodes for this. If there is a method easier than guess and check it would be good to know.

Also how were the origin and insertion of the muscles determined? In some cases the insertion points on the scapula do not seem to lie on the right side of the scapula i.e. the insertions of infraspinatus 5 and 6 seem to lie within the scapula / closer to the anterior side of the scapula. I know I could just adjust these slightly by hand but would like to know how they were determined before making the decision to adjust them.

Many thanks for your continued support.

Monique Jackson

Hi Monique,

The data fro both the bony landmarks and muscle origin/insertion data comes from the articles and references listed here:

http://wiki.anyscript.org/index.php/AnyBody_Managed_Model_Repository:_Body_Models#ShoulderArm

The data has been transferred from the global coordinate system they was measured in into a local segment coordinate system, some of them has been adjusted slightly if there reasons for it then there is a “modified” comment on the data.

You are right that there for some nodes is a mismatch between the points and the surface, this is because the original data did not contain a surface file.

Best regards
Søren

Hi Søren

Thanks for the reply. I just have a further two questions for you (based on the AAUHuman body model):

With regard to the humerus. The sphere used to represent the head of the humerus is offset slightly from gh (the difference is -0.002065, 0.000616, 0.000947). Can you explain why this is? I am aware the humerus head is not perfectly spherical and maybe it is to do with this but the offset seems to move the sphere in the opposite direction to what I expected. There were no comments in the code as to how the origin of the sphere was defined.

The wrapping surface used to represent the humerus for the teres minor - collum_hum_teres_minor - is centered on the HumerusBoneGeometryNode rather than gh as I expected. This results in the cylinder not being in line with the humerus - see attached figure. Can you explain the reason for this?

Thanks again for the help

Monique

Hi Monique,

The data used for the wrapping surfaces also originates from the references listed. In the references there was data for the center of the sphere used to replicate humerus and similar data fro the cylinder used for teres_minor.

Best regards
Søren

Hi Søren

Thanks for the continued help. I will review the references.

Monique