The Psoas muscle (pronounced so-az) is located in our central core and is the only muscle that connects our spine to our leg. This fascinating muscle has both biomechanical and biointelligent properties, meaning that it not only moves us around, but it also links our central nervous system to how we perceive our World. The Psoas is involved in every case of low back and hip pain, yet many people have never heard of this muscle.
The psoas complex is made up of two muscles: the psoas major and the iliacus, together referred to as the iliopsoas. (See fig. 1) The psoas major emerges from the 12th thoracic vertebrae and attaches to the sides of all 5 of the lumbar vertebrae. It flows down through the pelvis to attach to the upper inside of the thighbone, at the lesser trocanter of the femur. The iliacus is a fan-shaped muscle that lines the inside of the hip bones, and inserts into a mutual attachment on the lesser trocanter. There is a psoas complex on either side of the body, and when healthy and flexible, it stablizes the spine and keeps us upright. It provides a shelf for our internal organs, and initiates movement when we take a step to walk.
A keystone area of the body, the 12th thoracic vertebrae is also the origin site of the diaphragm, our muscle of breathing. This arrangement makes for an unfortunate connection between a tight psoas and a shallow breathing pattern, as the tight upper fibers of the psoas pull down on the diaphragm. Also, the upper psoas and diaphragm meet at the junction known as the solar plexus. In energetic terms, the solar plexus is a center for personal power and the control of feelings. In physiological terms, the solar plexus is a superhighway of nerves that relay information to and from internal organs, muscles, and the brain. These nerves travel through and on the surface of the psoas, which serves as a neighborhood path for some very complex internal communication. This is the bio-intelligent aspect of the psoas, yielding the mind/body connection and the meaning of “trusting your gut feelings”. As a matter of fact, the solar plexus includes the sympathetic nerve pathway to the adrenal gland, where adrenaline and cortisol are released during the “fight or flight” reaction. Therefore, a person who has a chronic stress overload can perpetually release adrenaline and cortisol, resulting in adrenal fatigue, poor digestion, and lowered immune functionas well as a tight psoas, leading to low back pain or movement issues. The person may have feelings of restlessness or anxiety, which they may not be able to pinpoint. There are many internal physiological events that are related to and dependent on a healthy psoas, yet most of us have no kinesthetic sense of this core muscle!
Other ailments that are linked to psoas imbalance include low back pain, sciatica, disc problems/arthritis, spondylolisthesis, scoliosis, hip and knee degeneration, arch support, and menstrual/infertility issues.
It is the vital and dynamic interrelationship of the psoas with the diaphragm, internal organs, blood flow, and nerves that gives the psoas muscle a powerful, unifying function.