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THE PROFOUND PSOAS – Functional Anatomy & Movement Integration A warm welcome to the seminar that encourages you to think, feel and move (differently)!

Our topic is the profound Psoas muscle. A discussion on all the various aspects associated with this topic, the muscles influence on other physical structures and our well-being, would exceed the frame of this seminar by far. Anyone who has devoted a considerable amount of attention to the body, movement and their mysterious ways presumably comes to the conclusion that human anatomy also obeys the law of relativity. My search for the “Psoas Truth” was a horizon expanding journey in which I gained a deeper knowledge of functional anatomy, but was also confronted with contradiction. Did I find the truth in the end? Partly, but the journey is still underway.

To date, the world of science, sport and bodywork research has discussed and debated the function of the Psoas in terms of both a mover and a stabilizer. Yet opinions amongst anatomists remain divided when it comes to attachment points, let alone the best ways to strengthen, stretch and release this fascinating muscle.

This seminar will therefore be combining facts and subjective elements, not only gained from my research, past education and work experience, but also from my own body.

We’ll be discussing and experimenting with the following aspects: § Origin and insertion. § Muscle course. § Psoas as connector. § Neighbouring structures. § Palpation. § Form & function. § Movement integration.

PSOAS The Psoas is often described as part of a muscle group called Iliopsoas. The Iliopsoas group comprises the Psoas major, Psoas minor (if existent) and the Iliacus.

Iliacus starts laminar on the inside of the ilium and continues running bundled across the hip joint. It shares a tendon with the Psoas major and inserts on the and just below the minor trochanter on the femur shaft.

Psoas minor is a disappearing muscle and only exists in about 50% of the population. Ordinarily it runs on both sides of the body like the Psoas major, however, it is possible to have one Psoas minor only. It originates from the 12th thoracic and 1st lumbar vertebra and inserts on the iliopectineal eminence (lateral to the pubic symphysis).

As the main topic of this seminar is the Psoas major, I’ll simply refer to it here after as the Psoas.

ORIGIN & INSERTION Fundamentals first: We have two Psoas muscles, one on the right and one on the left side of the spine.

Origin Insertion

§ Transverse processes of L1-L5 § Lateral sides of vertebral bodies of T12, L1-L5 § Intervertebral discs T12, L1-L5

§ Slightly distal to the minor trochanter

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MUSCLE COURSE Our evolutionary transformation from quadruped to biped changed the course of the Psoas. In our four-legged friends, the Psoas runs directly from the spine to the femur, whilst in the case of humans the hip joint is extended (or should at least be when in an erect posture). Because of this, the Psoas takes a rather unusual route from the spine, running from deep inside the body to the front of the pelvis and then back into a deep position on the inside of the thigh. In other words, the Psoas starts deep inside the abdominal cavity lateral to the lowest thoracic vertebra and the lumbar spine. The individual muscle attachments join and continue running anterior inferior until they cross the iliopectineal ridge and the hip joint. At the end, the muscle inserts via a tendon on the minor trochanter, which is on the inside of the “7-shaped” femur. Reference: The Anatomist’s Corner, The opinionated Psoas by Thomas Myers

PSOAS AS CONNECTOR The Psoas connects: § Top and bottom. § Inside and outside. § Axial and appendicular skeleton. § Breath and gait.

NEIGHBOURING STRUCTURES The Psoas has many influential neighbouring structures; here a list of some: § Hip joint. § Lumbar spine. § Sacrolumbar junction. § Thoracolumbar junction. § Kidneys. § Adrenal glands. § Iliac arteries. § Solar plexus. § Lumbar plexus (it lies within the Psoas – Reference: Myers 2000). § Diaphragm.

In the case of the most relevant neighbouring muscles, I’ll be avoiding certain classifications such as synergists and antagonists, as under certain circumstances antagonists can also work as synergists. Ok, here a list of important neighbours and friends (Reference: Myers 1998). § Iliacus.

o Anterior pelvic tilt, hip flexion. § Quadratus lumborum.

o Anterior pelvic tilt, lumbar extension, lateral flexion, rotation. § Pectineus.

o Anterior pelvic tilt, hip flexion, adduction, lateral hip rotation. § Piriformis.

o Posterior pelvic tilt, hip extension, lateral hip rotation. § Gluteus maximus.

o Posterior pelvic tilt, hip extension, lateral hip rotation.

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MUSCLE FORM & FUNCTION In our upright posture the Psoas looks and feels like a fusiform muscle. Similar to quadrupeds, the Psoas used to act, and indeed still does, as a triangular (radiate or convergent) muscle.

Like the Deltoid muscle the Psoas can be involved in a variety of actions.

Here a speculative list of muscle functions in sagittal plane.

Psoas-Portion Function

Inferior, medial fibres pull L4 and L5 anterior (Myers 1998).

Extension of the lumbar spine. Likely consequence: anterior tilt of the pelvis.

Superior, lateral fibres (including Psoas minor if existent) pull T12 and L1 towards the groin, leading to lumbar flexion. Whether this actually occurs, however, depends on the mechanical axis of the lumbar vertebrae and their relative position to the hip joint (Myers 1998).

Flexion of the lumbar spine. Possible consequence: posterior tilt of the pelvis.

Assuming these statements to be correct, the actions of the upper and lower portion of the Psoas neutralize themselves. In other words, they will balance each other and stabilize the lumbar spine in its natural lordosis.

FLEXION IN THE HIP JOINT Viewed from the side, one can see the course of the Psoas: from the spine down and to the front of the pelvis, across the hip joint, then down and in again to the inside of the femur. With a fair degree of certainty then, we can say that the Psoas is a hip flexor. Reference: The Anatomist’s Corner, The opinionated Psoas by Thomas Myers

ROTATION OF THE HIP JOINT Does the Psoas rotate the hip joint and if so, medially or laterally? Opinions are divided. Because the muscle insertion is on the minor trochanter, which is slightly posterior to the midline of the femur, the most common opinion is that the Psoas is a lateral rotator. However, this can change depending on the position of the pelvis and femur. To shed yet more light onto the (in)significance of this question, let’s look at the Psoas’ lever strength as a rotator. As the insertion is medial and not lateral, its power as a rotator is very low. Because of this, I will include its function as a rotator in our thinking model, but in a playful, easy manner. So we’ll include lateral and medial rotation in the practical movement applications – better to be safe than sorry.

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EXTENSION OF THE LUMBAR SPINE The lower, more medial fibres of the Psoas pull the lower lumbar vertebrae anteriorly; thus creating extension in the lower back and a related anterior pelvic tilt.

Reference: The Anatomist’s Corner, The opinionated Psoas by Thomas Myers

FLEXION IN THE LUMBAR SPINE The upper, more lateral fibres of the Psoas pull the last thoracic and top lumbar vertebra inferior, which can create a posterior shift in the vertebrae underneath. If this occurs, the lumbar spine flexes and a related posterior pelvic tilt can result.

STABILISATION OF THE LUMBAR SPINE Dual traction neutralizes the action of the lower and upper fibres of the Psoas , their activation thus contributes to lumbar stabilisation. This synergy supports the balance of the thorax on the pelvic girdle.

LATERAL FLEXION OF THE LUMBAR SPINE If the Psoas contracts on one side (unilateral), the lumbar spine will laterally flex towards the shortened muscle.

ROTATION IN THE LUMBAR AND THORACIC SPINE Rotation often follows lateral flexion. However, due to the very limited rotational range of movement in the lumbar spine (approximately 1° per segment), the main movement is transferred up into the thoracolumbar junction. Due to the slight diagonal fibre arrangement (inferior anterior), the rotation is contralateral - in other words, away from the shortened muscle (the navel is pointing away from the shortened Psoas). Reference: The Anatomist’s Corner, The opinionated Psoas by Thomas Myers

SYNERGY WITH THE DIAPHRAGM The Psoas has a direct fascial connection to the respiratory diaphragm. All other facets of this connection aside, the Psoas and the diaphragm are key components for a natural, elegant and easy gait. We can say then, that the activity of the Psoas is initiated by the breath and that our walking motion starts at the 12th thoracic vertebra.

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REFERENCES § The Anatomist’s Corner, Issues in Structural Anatomy by Thomas Myers § Body 3, A Therapist’s Anatomy Reader by Thomas Myers § Trailguide to the Body by Andrew Biel § Manual of Structural Kinesiology by Clem W. Thompson and R.T. Floyd § The Psoas Book by Liz Koch

I hope you enjoyed the seminar and it gave you food for thought and new impulses for your work as a movement teacher. I look forward to continuing and building on this. In the meantime, I wish you much success and satisfaction for your teaching. Warm wishes

Karin Sharp-Gurtner Principal & Educator

art of motion training in movement® www.art-of-motion.com Email Switzerland info@art-of-motion.com Email Australia move@art-of-motion.com