Originally published in the AMT Journal "In Good Hands", June 2009
© AMT 2009, © Colin Rossie 2009. Not to be printed or used without permission of the copyright holders and acknowledgement of original publication.
In the last issue of In Good Hands, the contributions to the clinical perspectives article devoted to sciatica were so impressive that there seemed nothing of further significance that I could add. Jeff Murray mentioned the synergistic relationships of soft tissues in the pelvic girdle and the mechanics of force closure and form closure in pelvic and sacral function. He also discussed the role of stability versus strength in hip dysfunction. A few issues back (June 2008), there was a multi-contributor article on psoas function. From my perspective, there is a definite relationship between the two articles.
Although psoas isn’t always a first consideration in the treatment of sciatica, its dynamic relation to piriformis in stabilising the pelvic girdle should not be overlooked. These two muscles each cross the sacro-iliac and hip joints as ‘three-dimensional’ muscles and act synergistically to affect sacral biomechanics and stability as well as work to maintain the balanced position of the sacrum. I would like to add some other information on sciatica, and expand on that with some thoughts drawn from a Rolfing®/Structural Integration (SI) perspective.
On Sciatica: Historical Titbits, Description and Additional Considerations
The term sciatica was originally used in ancient times to describe any hip and buttock pain. From the mid 18th century, it has been used to describe pain in the buttock and posterior thigh originating from the sciatic nerve. ‘True’ sciatica was once thought of as a neuritis (inflammation) that occurred in untreated diabetes or severe alcoholism.(1) Now the term is commonly used to describe a neuralgia resulting from impingement of the sciatic nerve that results in pain, tenderness and paraesthesia, usually unilateral, in the buttock, posterior thigh and lower leg.(2,3) In addition to pain, gait can also be affected and in extreme cases, there can also be muscle wasting in the lower leg.
The sciatic nerve arises from L4–S3 nerve roots.(4) As Kerry Hage, Alan Ford and Jeff Murray all mentioned, pain can originate at the nerve roots, but it is useful to differentiate radicular the pain originating in nerve roots from neuralgia arising from the sciatic nerve. In the former, pain will be present in the lower back and maybe also in the buttock and thigh but not in the lower leg. In the latter, it will be absent in the lower back but present in the posterior thigh and below the knee. The distinction here is between central nerve root and peripheral nerve involvement. Bogduk argues, ‘the only pain that has ever been produced experimentally by stimulating nerve roots is shooting pain in a band-like distribution. There is no physiological evidence that constant, deep aching pain in the lower leg arises from nerve root irritation’.(5)
Anatomical and Functional Considerations
The sciatic nerve is the longest and widest peripheral nerve in the body. It exits from the greater sciatic foramen via the superior sciatic notch just anterior to the piriformis muscle and has peroneal and tibial portions. It supplies the hamstrings and adductor magnus, and its branches supply most of the lower leg. Also exiting the greater sciatic foramen are the inferior gluteal nerve, the posterior femoral cutaneous nerve, and the nerves supplying the other external rotators—basically, all the nerves that supply all the gluteal region and the posterior thigh and calf.
The piriformis muscle originates on the anterior surface of the sacrum and exits the inner pelvic bowl through the greater sciatic foramen to insert onto the upper border of the greater trochanter. It is a postural muscle, with type I fibres that shorten and tighten in response to overload. If these fibres become engorged and swollen in the limited space of the sciatic foramen, then piriformis will impinge on the sciatic nerve.
As Jeff noted, there is great anatomical variation in the relationship of the sciatic nerve to the piriformis muscle. In 85% of people both portions of the sciatic nerve pass anterior to the piriformis muscle; in 10% only the tibial portion is anterior to the piriformis, while the peroneal portion goes through the muscle; in 2–3% the peroneal portion starts superior and runs posterior to the muscle; and in 1% both portions travel together through the middle of the muscle belly.(6) If present, these structural anomalies could easily result in sciatic nerve impingement in the event of any myofascial dysfunction.
Travell and Simons note that, in addition to entrapment of the nerve by piriformis being responsible for sciatica, the referral pattern from active myofascial trigger points in piriformis mimics the pain pattern of sciatica. They also note that active trigger points in gluteus minimus and the anterior portion of gluteus medius can have similar referral patterns, which they term ‘pseudo sciatica’.(6)
Though frequently overlooked, the external rotators (piriformis, gemellus superior and inferior, obturator externus and internus and the quadratus femoris) are also postural extensors of the hip joint. When talking about hip extension, usually the hamstrings come to mind as the hip extensors. While that is undeniably their function, it is worth noting that as long muscles with a linear alignment of myosin and actin fibres that cross two joints, they are not the most efficient way to maintain upright stance at the hip joint. On the other hand, the external rotators, if thought of as short extensor muscles, are short, single-joint muscles responsible for form closure of the sacro-iliac articulation, thus bringing great postural stability to the pelvis.(7,8) Perhaps it would be useful to differentiate between femoral and coxal components of hip extension.(7)
There is a distinct relationship between the role of the hip external rotators—especially the piriformis—and the psoas. Both psoas and piriformis travel anteriorly, inferiorly and laterally from their origins to their insertions: the psoas from the anterior vertebral bodies of the lumbar spine to the lesser trochanter of the femur, the piriformis from the anterior surface of the sacrum to the upper border of the greater trochanter of the femur. The piriformi run primarily horizontally to their attachment, while the psoas run vertically.
If one considers the body from a tensegrity viewpoint, the psoas can be seen as a guy wire pulling the lumbar spine forward, countering the pull of the posterior guy wire of the lumbar erectors,(9) not only via the attachment of their deeper fibres to the lumbar spine,(5) but also through the thoraco-lumbar fascia.(10) Similarly, a fan around the hip consisting of the external rotators, gluteus minimus and the anterior fibres of gluteus medius can be seen as the tensegrity opposite of the iliacus in the ilium.
Piriformis is the tensegrity antagonist to the psoas around the sacro-iliac joint. An active psoas pulls the lumbar spine (and also indirectly the superior anterior surface of the sacrum) forward and down, affecting the position of the superior sacro-iliac joints, whereas the piriformis activates to counter this, bringing the anterior, inferior sacrum forward, thus creating a seesaw effect on the sacrum. The two muscles work together to allow optimal balance of the lumbosacral junction and the functioning of the inferior and superior SIJs around the body’s centre of gravity. This action balances the bones of the pelvis and ensures the congruence of the centre of gravity with the body’s centre of mass.
An Evolutionary Digression
It is worthwhile to digress slightly here and consider the hips from an evolutionary perspective. Over time, to accommodate the change to upright stance and bipedal gait, the hip girdle has changed shape and orientation. The direction of the ilia has changed. A deep iliac fossa has developed that allows a greater attachment area for the gluteus minimus, gluteus medius and external rotator muscles laterally and the iliacus medially. The ilia have twisted anteriorly to a more lateral and anterior orientation. Our nearest primate relatives have posterior facing ilia with small to non-existent iliac fossae. Their gluteus medius and minimus muscles extend the femur. In humans, these muscles abduct the femur at the hip joint in order to prevent a Trendelenberg gait. Moreover, the sacrum has increased in width and the complexity of its articulations in order to enhance stability. Consequently, the external rotators have taken on the extra functions of pelvic stabilisers and extensors.(11,12)
Rolfing®/ SI Definition and Perspective
SI, of which Rolfing®, Hellerwork and Tom Myers’ KMI (Kinesis Movement Integration) are probably the most commonly known varieties, is a specific body of work based on the teachings of Dr Ida Rolf (1896–1979).(13,14) The goal of the SI process is the optimal dynamic alignment of the body in relationship to gravity and the three-dimensional space around it (what a mouthful!). This most frequently occurs as an outcome-oriented process over ten or so sessions,(15) each session having a specific goal (see box). There is a long tradition and strong emphasis on the functional aspect of anatomy in the SI tradition, as witnessed not only in Ida Rolf’s only published work,(16) but also in such publications as Tom Myer’s Anatomy Trains(17) and the many research contributions made by SI practitioners to our current understanding of fascia.(18, 19, 20, 21, 22, 23, 24,25,26,27,28)
In the sciatica article, Jeff Murray stated that in hip dysfunction a tight piriformis might be all that provides stability to the pelvis and that to work initially to counter this could lead to even greater instability. I am in total agreement with him. Ida Rolf devoted a lot of her book to the role of the external rotators and the psoas around the pelvis.(16) In the classic SI process, work on the piriformis and other hip stabilisers is only commenced in the sixth session, once all the synergistic relationships in the hip girdle have been addressed in previous sessions. In SI, stability in the pelvis is addressed right from the first session, where the superficial gluteals are worked and balance between the hamstrings and quadriceps are themes.
This is ramped up in the third session, where attention is given to the TFL, ITB, gluteus medius anticus and fascial convergences at the trochanter, as well as the relationship of the pelvis to the ribs and the contra-lateral gluteus maximus/ latissimus dorsi relationship. The fourth session prepares for more thorough work on the pelvis, consisting of much work on the adductors, the lower insertion of the psoas and the ischial rami and tuberosities, sacrotuberous ligament and obturator membranes, and commences work with core activation and stability. Much of the moment work of this session focuses on synergistic, melodic relationships in the pelvic myofascia.
These themes continue into the fifth session, with work on the iliopsoas addressing issues of balance in the abdomen between the rectus and transversus and the rectus and psoas, as well as balance in contralateral gait - all in preparation for the sixth session. The later integration sessions are based on the relationship of upper and lower body to the pelvis (for a fuller description of the structural integration process, see Maupin 2005 and Myers 2004a, 2004b, 2004c.(29, 13, 15, 31),
Conclusion
I dislike the Cartesian view of the body as a ‘soft machine’ and am not fond of seeing it compared to inanimate objects such as machines or buildings. Living beings are far more complex and interesting than that. However, I will use two analogies to elucidate the ideas what I have attempted to express in this article.
If you compare the body to a carriage or chariot, the psoas can be thought of as the drawbar or pole and the piriformis as the axle attaching to it. The external rotators and the iliacus are the outer and inner spokes of the wheel. Maupin provides a distillation of the structural integration view when he says, ‘Much as the external rotators are the key to the sacrum, the piriformis is the key to the rotators’.(30) Further, from a tensegrity perspective, each of the spokes needs to be able to play their part in the balanced function of the wheel.(29,7) Thus, the two piriformi can be considered a prevertebral muscle axle, stretching from femur to femur. Their horizontal orientation and the psoas’ vertical orientation is responsible for the three-dimensional space in the area between the ribs and the legs. Together the piriformis and psoas support the lumbo-sacral junction—the central joint of the body—as well as hold the front of the spine back with the support of the legs.(30)
The sacrum itself is the keystone bone of the pelvis in both stance and movement. To continue with the architectural analogy, the pelvis is the arch spanning the columns of the legs, where they meet to support the vertebral column and the superstructure of the torso above. Pelvic floor muscles attach to its inferior aspect (the sacral apex); its superior aspect (the sacral base) provides the foundation for the vertebral column. Additionally, the sacrum is the body’s transverse centre of gravity.
Thus, the dynamic relationship between the piriformis and the psoas plays a crucial role in the efficient functioning of the sacrum. A properly functioning sacrum influences core tone and stabilisation. As the “keystone” of the body below the cranium, all structures (osseous and soft tissue) that attach to it are vital for optimally efficient upright stance.
References
(1) Cailliet R. Low back pain syndrome: 5th edition. Philadelphia: FA Davis Company, 1995.
(2) Lee D. The evolution of myths and facts regarding function and dysfunction of the pelvic girdle in Vleeming A, Mooney V, Stoeckart R.(eds) Movement, stability and lumbopelvic pain: 2nd edition. Churchill Livingstone, 2007.
(3) Willard FH. The muscular, ligamentous and neural structure of the lumbosacrum and its relationship to lower back pain in Vleeming A, Mooney V, Stoeckart R.(eds) Movement, stability and lumbopelvic pain: 2nd edition. Churchill Livingstone, 2007.
(4) Kendall F, McCreary E, Provance P, Rodgers M, Romani W. Muscles: testing and function, with posture and pain: 5th edition. Baltimore: Lippincott Williams and Wilkins, 2005.
(5) Bogduk N. 2005 Clinical anatomy of the lumbar spine and sacrum: 4th edition. Churchill Livingstone, 2005.
(6) Travell J, Simons D. Myofascial pain and dysfunction: the trigger point manual, vol 2: the lower extremities. Baltimore: Lippincott, Williams and Wilkins, 1983.
(7) Myers T. Extensor coxae brevis: treatment strategies for the deep lateral rotators in pelvic tilt in Beech M, Kemper P, Schumaker K.(eds) Missoula: IASI 2009 Yearbook of Structural Integration IASI, 2009.
(8) Richardson C, Hodges P, Hides J. Therapeutic exercise for the lumbopelvic stabilization: 2nd edition. Churchill Livingstone, 2004.
(9) DeRosa C, Porterfield J. Anatomical linkages and muscle slings of the lumbopelvic region in Vleeming, A, Mooney V, Stoeckart R.(eds) Movement, stability and lumbopelvic pain: 2nd edition. Churchill Livingstone , 2007.
(10) Gracovetsky S. 2007 Stability or controlled instability in Vleeming A, Mooney V, Stoeckart R.(eds) Movement, stability and lumbopelvic pain: 2nd edition. Churchill Livingstone, 2007.
(11) Lee D. The pelvic girdle: 3rd edition. Churchill Livingstone, 2004.
(12) Lovejoy CO. Evolution of the human lumbopelvic region and its relationship to some clinical deficits of the spine and pelvis in Vleeming A, Mooney V, Stoeckart R.(eds) Movement, stability and lumbopelvic pain: 2nd edition. Churchill Livingstone, 2007.
(13) Myers T. Structural integration: developments in Ida Rolf"s ‘recipe’: part 1. Journal of Bodywork and Movement Therapies 2004a;8(2):131–142.
(14) Smith J. Structural bodywork. Churchill Livingstone, 2005.
(15) Myers T. Structural integration: developments in Ida Rolf"s ‘recipe’: part 2. Journal of Bodywork and Movement Therapies 2004b;8(3):189–198.
(16) Rolf IP. Rolfing: re-establishing the natural alignment and Structural Integration of the human body for vitality and well-being. Rochester: Healing Arts Press, 1977.
(17) Myers T. Anatomy trains: 1st edition. Churchill Livingstone, 2001.
(18) Schleip R. Fascial plasticity—a new neurobiological explanation: part 1. Journal of Bodywork and Movement Therapies 2003a;7(1):11–19.
(19) Schleip R. Fascial plasticity—a new neurobiological explanation: Part 2" Journal of Bodywork and Movement Therapies 2003b;7(2):104–116.
(20) Schleip R, Klingler W, Lehmann-Horn F. Active fascial contractility: fascia may be able to contract in a smooth muscle-like manner and thereby influence musculoskeletal dynamics. Medical Hypotheses 2005;65:273–277.
(21) Evanko S.P &Vogel,K.G. “Ultrastructure and proteoglycans composition in the developing fibrocartilagenous region of bovine tendon.” Matrix 1990 10: 420-36
(22) Evanko S.P &Vogel,K.G “Proteoglycan synthesis in the fetal tendon is differentially regulated by cyclic compression in vitro.” Arch Biochem Biophys 1992. 298: 303-12
(23) Robbins, J.R., Evanko S.P &Vogel,K.G “Mechanial Loading and TGF-beta regulate proteoglycans synthesis in tendon” Arch Biochem Biophys 1997 342:203-11
(24)Evanko S.P., Tammi, M.I., Tammi,R.H. & Wight, T.N. “Hylauron -dependant pericellular matrix" Adv Drug delivery Review 2007
(25) Chaudry, H.R. Schleip, R., Ji, Z., Bukiet, B., Maney, M. & Findley, T” Three Dimensional mathematical modelfor deformation of human fasciae in manual therapy” Journal of the American Osteopathic Association 2008,108: 379-90
(26) Evanko, S. “Extracellular matrix and the manipulation of Cells and Tissues.” IASI Yearbook 2009 61-68
(27) Cottingham, J.T, Porges,S.W. & Richmond, K. “Shifts in Pelvic Inclination Angle and Parasympathetic Tone Produced by Rolfing Stoft Tissue Manipulation.” Journal of the American Physical Therapy Association 1988 Vol 68 no9 1364-1370
28) Cottingham J. T, Porges,S.W. & Lyon, T. “Effects of Soft Tissue Mobilization (Rolfing Pelvic Lift) On Parasympathetic Tone in Two Age Groups.” Journal of the American Physical Therapy Association 1988 Vol 68 no3 352-357
(29) Myers T. Anatomy Trains: 2nd edition. Churchill Livingstone, 2008.
(30) Maupin E. A dynamic relation to gravity, vol 2—the ten sessions of Structural Integration. Dawn Eve Press, 2005.
(31) Myers T. Structural integration:developments in Ida Rolf"s ‘recipe’: part 3. Journal of Bodywork and Movement Therapies 2004c;8(4):249–264.
Also worth consulting for further elucidation would be the following websites:
http://www.anatomytrains.com/
http://www.somatics.de/
