Low Back Anatomy Muscle. Ad Non-Invasive Safe Pain Solutions. The intrinsic back muscles are found deeper to the extrinsic muscles separated from them by the thoracolumbar fascia.
They help to bend the back to one side or the other. The extrinsic superficial back muscles which lie most superficially on the back. The superficial or extrinsic back muscles allow for the movement of the limbs.
The back muscles are anatomically layered into superficial extrinsic and deep intrinsic muscles.
The psoas is a hip flexor muscle as is the quadriceps muscle. These muscles are also called immigrant muscles since they actually represent muscles of the upper limb that have migrated to the back during fetal development. The erector spinae is composed of three subgroups. The extrinsic back muscles are located in the back but act to produce movements of the shoulder and assist respiration.
