The psoas is a muscle that has received large amounts of discussion in varying circles. It has been called the “muscle of the soul“. There have been many other suggestions as to connections the psoas has between mechanical dysfunction and seemingly correlated physiological dysfunction…that is not what will be discussed here. Before even attempting to consider possible physiological dysfunctions related to the psoas we have another problem, and it seems like a bit of a big deal, we are not presented with any form of consistent agreement as far as the full functional role of the psoas. The psoas is a muscle of investigative controversy! So, let us take a look at some of the available information and see where it points us.