Deep muscles and functions of the spine

Iliopsoas – walking muscle, organ of perception, effects respiration, nervous system, immune system

Psoas major muscle: originates from T1 (thoracic one), continues along the entire spinal column/including the discs and inserts at the lesser trochanter of the femur.

Iliacus muscle: runs from the iliac fossa to the lesser trochanter.

The psoas major and iliacus muscle unite to become the iliopsoas muscle. Both muscles are surrounded by the iliac fascia. The iliopsoas muscle is the strongest flexor of the hip joint important walking muscle. Because the Iliopsoas muscle inserts at T1, it also impacts respiration.

When tight for an extended period, it can hold you in the ‘fight or flight’ side of the nervous system, keeping you in a state of alert, leading to adrenal fatigue and possibly lowering the function or turning off the immune system altogether. The iliopsoas also plays a significant role in the movement and stabilization of the pelvis.

Quadratus Lumborum – stabilizing muscle

The Q/L muscle is a muscle of the posterior abdominal wall lying deep inside the abdomen and dorsal to the iliopsoas. Starting from the iliac crest of the ilium and from there attaching to the 12th rib and the transverse processes of the 1st to 4th lumbar vertebrae. All fibers together give the muscle a rectangular appearance.

The Q/L fills a great amount of space within the abdomen and is therefore near many structures. The colon, the kidneys and the diaphragm are located ventrally to the muscle.

Essentially, the quadratus lumborum contributes to the stabilization and movement of the spine and the pelvis. Overuse and strain of the quadratus lumborum are one of the major causes for chronic pain in the lower back.

One typical cause is the habit of sitting at the desk using a reclined seat, which releases the intrinsic back muscles and weakens them in the long term. The weak back muscles must now be compensated by the quadratus lumborum leading to painful tension and stiffening of the muscle.

Other causes can be direct damage or any type of imbalance of the pelvis or spine which forces the quadratus lumborum to stabilize them.

Piriformis – external rotator of hip and abductor.

The piriformis is a flat, pyramid-shaped muscle that lies parallel to the gluteus medius muscle’s back margin and underneath of the gluteus maximus muscle.

The muscle passes through the greater sciatic foramen (a space in the pelvic bones, on each side of the center) and to the upper part of the greater trochanter

It is a small muscle when compared to other muscles of the region. The piriformis helps rotate the hip. It will rotate the thigh while extended and will abduct, or pull inward, the thigh when flexed.

The close nature of the piriformis muscle to the sciatic nerve, which is the largest nerve in the human body, can cause pain in some individuals.


Imagine the multifidus muscles moving like zip all the way up your spine.  Moving bones, moving segments of the spine, stabilizing side movement/lateral movement.  Think of this as the scaffolding for the back, they crisscross and connect to the intervertebral muscles, without these, your discs would compress, facets joints would erode.

Working with the forward and back plane will strengthen them, but overdone can weaken them and stiffen the back.  Lateral movement and rotation to release them.

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