Hey Sandra,
these are very good questions to ask and understand the body's general and specific reactions to trauma and stress triggers. The psoas is one important muscle to react in a defensive way, making us into a tight ball and preventing expansion. It affects many other muscles too which impact our posture. To dive into that I can share a [https://www.meta-health.net/tiki-download_file.php?fileId=2309|free ebook] by [https://www.corewalking.com/blog/|Jonathan Fitz-Gordon] "It's all about the Psoas".
 Another muscle to tighten is the trapeze muscle between our neck and shoulders. So, depending what we attempt to protect - the belly or the head - different muscles or muscle groups will tense up. These are not mainly self-devaluation conflicts at play but rather "attack"-conflicts - I want to discuss this in our next class.
The [https://www.meta-health.net/tiki-download_file.php?fileId=2212|TRE exercises] target mainly the psoas to shake trauma energy out and to release pain. When we do them lying down, the waves and vibrations will reach the whole body - it's worth to explore that with any "trauma pain" client! And to also feel for other impulses to move and discharge energy of held-back actions.
Thank you for sharing about the book!