The psoas – pronounced ‘so-az’- is one of the most important muscles in the body. It is considered to be one of the body’s core muscles. It is the only one to connect the upper and lower body. It is actually made up of 2 muscles – the psoas major and psoas minor. The psoaz minor has little function and in about 40% of people is absent. For this reason, when the psoas is referred to, it is the major muscle that is meant.
The psoas is also part of the muscle grouping with the illiacus (which lines the pelvic bones) to form the ilipsoas.
Where are they?
The psoas attaches to either sides of all the lumbar vertebrae (L1-L5) of the spine (and sometimes the T12 of the thoracic vertebra). The other ends attach to both lesser trochanter of the femur (the ball end of the femur that fit into the hip sockets). The location of the psoas and the nearby organs means that it is quite difficult to directly reach the psoas itself through palpation.
What does the psoas do?
The location of the psoas in joining upper and lower body, underlines it’s significance in significant movements of the body.
- Flexing the trunk of the body, eg when you sit up from a lying position
- Laterally rotating the hip, eg when kicking a ball with the inside of your foot
- With the Iliopsoas it is the main flexor of the hip
The spinal attachments of the psoas, however, also means it plays a part a part as a postural muscle and stabiliser between back extension and flexion. Research has suggested that it can help erect the lower spine. It is easy to see how the psoas is connected to lower back problems.
It is interesting to note that the psoas’ proximity to organs such as the kidneys, liver, spleen, pancreas, intestines, bladder and stomach means that any contraction of the muscle helps to stimulate and massage them.
Keeping the psoas healthy
The many facets of the psoas means that it can easily become overworked. It is important make sure that the muscles it relies on – the abdominals, spinal extensors, posterior muscles such as the gluteus maximums and quadratus lumborum – are strong.
The psoas benefits from exercises that build or maintain strong and flexible core muscles, postural stability or body alignment and flexibility, especially in the hip and spine. This includes pilates and yoga based.
3 December 2015.