Psoas major joins at the ilacus (muscles that line the front of your hip bones) at the groin to form iliopsoas, which includes psoas major, iliacus, and in 50% of the population, a smaller, parallel, and partially separate psoas minor muscle. These deep abdominal muscles act as the strongest flexors of the thigh at the hip.
The left and right psoas, together with the left and right spinal erector groups (spine stabilizers and extenders), are "arrayed around the spinal column like four guy wires around a mast." In sitting or standing, the right and left psoas work bilaterally to stabilize the vertical spine. In sidebending and twisting, they work unilaterally to exert powerful torques on the spine.
The psoas can be extremely sensitive due to its proprioceptive function in upright postures and due to the numerous nerves that pass around, within, and through its muscle mass. Even though these muscles lie deep to the viscera and may be difficult to palpate on some clients, strong pressure is rarely, if ever, required to relieve the pain and hypertension.
- sitting for extended periods with the hips in a flexed position, especially sitting with the knees up
- strenuous running or climbing
- workout regimes that overwork the midsection such as sit-ups or leg-ups
- habitual stooping, leaning, or slouching posture
- sleeping in a fetal position
Finando, Donna & Finando, Stephen. Trigger Point Therapy for Myofascial Pain: The Practice of Informed Touch. Rochester: Healing Arts Press, 2005. Print.
Luchau, Til. Advanced Myofascial Techniques: Neck, Head, Spine and Ribs. Scotland: Handspring Publishing Limited, 2016. Print.
“Psoas Major.” Yoga Teacher Resource. 2 January 2014, http://teachingyoga.net/all-about-the-psoas-major-tips-from-a-physical-therapist-yoga-instructor/.
2012, August 14. Psoas Muscle [digital image]. Retrieved from http://aaron-chiropractic.blogspot.com/2012/08/learn-about-psoas-muscle-and-its.html
David G. Simons, Janet G. Travell, Lois S. Simons. Psoas Trigger Points [digital image]. Myofascial Pain and Dysfunction: The Trigger Point Manual, Vol. 2 - The Lower Extremities. Lippincott Williams & Wilkins, 1992.