fix: Updated insertions and origin for Gluteus medius

[melund]

Updated the Gluteus Medius insertions and origin points, to ensure the muscles has correct moment arm for external rotation in certain postures.

@divyaksh-chander identified some postures where gluteus medius failed to provide the necessary external rotation moment. This could be fixed by refining the gluteus medius insertions to better match what we observed from different anatomical dissection videos. The posterior part of gluteus medius twists inside the anterior part and insert more anteriorly on the femoral trochanter.

Most anatomical text book doesn't show this complexity of the fiber alignment. But some do like for example this one:

(source: https://movewellacademy.com/muscle-minute-tuesday-meet-the-gluteus-medius/)

The following images show before and after this fix:

[depierie]

Hi @melund and @divyaksh-chander , sorry for the late reply.

I did not know the exact anatomy of the different gluteus medius regions, but it seems to make sense, especially if you saw this anatomy in dissection videos.
I also found this article which seems to confirm you new alignment:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1256751/pdf/janat00044-0181.pdf

It also reports separate innervation for posterior, mid, and anterior section (so justifies treating them as independent muscles during recruitment optimization), and also attributes different functions to the different sections.
In general they seem to infer function from anatomy.

I'm wondering if there's any paper out there that directly measured lever arms on cadavers that could confirm that the new wrapping is more realistic also from a functional and more quantitative perspective, in addition to anatomical visual matching.

Btw, how do the new lever arms look? Does the glut med post's external rotation lever arm increase in all internally and externally rotated postures? And does it also become a more efficient hip extensor now?
(https://doi.org/10.1371/journal.pone.0204109.s012)
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0204109