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Just for a bit of context: I am trying to create a 3D digital model of the human skeleton as the first step towards computer generated muscle simulation, and as such I want the skeleton to be as anatomically and biomechanically correct as possible. However, I am currently struggling with the movement of the ribcage. I am quite capable in the 3D side of things, but without any medical background I've essentially had to learn everything about the skeleton so far from the ground up.

Whilst there is plenty of information on the internet about the movement of the ribs and sternum during inspiration and expiration, I haven't been able to find any detailed descriptions/diagrams/animations of how the various movements of the thoracic spine (lateral flexion, sagittal flexion and extension, and axial rotation) influence the positioning of the ribs, including in scientific papers (however I can't see that this topic hasn't come up before?).

The only thing I've found for this are three diagrams from this website http://body-disease.com/movements-in-the-thoracic-region/ (bottom right hand corner in each case):Axial Rotation Lateral FlexionSagittal Flexion and Extension

Whilst these diagrams are definitely helpful in showing the general movements and shape, they don't really have the detail that I am looking for: for example the movement of the sternum isn't specified or the exact movements of the ribs and costal cartilage. These diagrams are a good starting point but I can't really work with them - as really I need to understand the four movements of each rib (torsion, calliper, bucket handle and pump handle) where they connect to the thoracic spine in order to create an accurate 3D model.

I would most like an accurate diagram or (even better) an animation of the spine movements with a complete rib cage; however X-ray images, sketches or anything that might provide more information would be useful. Descriptions are also great but as I'm not very experienced with anatomy I may not be able to glean as much information from text as I would from images. Essentially I am not trying to understand the concept of how the rib cage changes, but the specifics of this complex movement.

I know this might be quite a specialist topic (especially given the lack of online information) however I thought I would ask anyway in case anyone knew. Thanks for any information you can give me!

(Also let me know if I've made an error - this is my first forum question)

Edit: after some more digging I've found this image (from http://www.orthotech.ethz.ch/research/musculoskeletal-biomechanics/sarcopenia--implications-of-age-related-muscle-loss-for-spinal-p.html) showing thoracic flexion and extension, which may help in understanding the sorts of thing I'm after. the issue with this image is the fact that the movement of the sternum and costal cartilage is still very unclear: enter image description here

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  • $\begingroup$ What benefit can one have from such 3D digital model? $\endgroup$ – Jan Jun 21 at 12:10
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    $\begingroup$ @Jan I want to use the skeletal system as the basis for simulating muscles, fascia and other tissues present in the body to create a photorealistic human which can be used for CGI. The idea is to adjust the different settings of the model (such as muscle definition or amount of fat) to quickly create a vast range of realistic 'humans'. The advantage to conventional 3D modelling would be accuracy (see Weta Digital's 'Tissue' software as a good example). I'm using the open source software "Blender" and I hope to make the system free to use for all if I get it to a point where I'm happy with it. $\endgroup$ – Robert Gregson Jun 21 at 15:10

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