Thursday, October 1, 2015

Head Forward Posture: Part 1

One of the most common postural disparities I see is a head-forward posture. In The Physiology of Joints, Volume III, French surgeon and anatomist Adalbert I. Kapandji states that for every inch the head goes forward it gains an additional ten pounds of weight in terms of strain on the posterior neck and upper back muscles. The average weight of the head is about 4.5-5 kg (10-11 pounds) and, in a balanced posture, it is supported evenly amid the muscles of the neck. With a head-forward posture, this balanced support is disrupted, and the posterior neck and upper back muscles then become increasingly more overloaded (and painful) with every additional degree of head-forward posture. With the head an inch forward (neutral is considered as consisting of the ear aligning over the acromion process which is the highest point of the shoulder) this means that the posterior neck and upper back muscles have to support about 20 pounds of weight all day. At 2 inches forward, this becomes about 30 pounds. With Americans spending more and more time behind the wheel, in front of computer screens, glued to cell phones and tablets, and performing other activities which lend themselves to this already common posture, it is not surprising that we frequently see so many problems attributed to this posture.

This is the first post of a three-part article about the implications of the head-forward posture. Part One (today’s post) discusses some common pain syndromes to which it contributes. Part Two will discuss the relationship of this imbalance to the shoulder girdle and will look at the sinew channel relationships. These two parts will be useful for patients and those suffering from the painful conditions described below; they will also be useful for acupuncturists who want to understand how improving posture can improve treatment results.

Part Three will explore the relationship of this imbalance to the zangfu (primary organ systems discussed in TCM). This will be largely for the benefit of practitioners of acupuncture, tuina and other modalities used in Traditional Chinese Medicine. 

The following are common complaints that involve a head-forward posture:

Generalized neck pain and shoulder pain caused from muscle overuse: As stated above, for every inch the head moves forward, it gains an additional 10 pounds of weight in terms of strain on the posterior neck and upper back muscles. What this means is that the muscles of the posterior cervical spine are working overtime, day in and day out, and for a prolonged time. It is just a matter of time before they start to cry out for some attention and that usually comes in the form of aches and pain. Specifically, the upper trapezius, levator scapula, and splenius cervicis are frequent muscular contributors to neck discomfort; they not only produce pain, but reduce range of motion and can contribute to stiffness, including stiffness which makes it difficult to turn the neck. Generally, restriction in the upper trapezius manifests in reduced range of motion and discomfort towards the end of the range of motion when looking in the opposite direction, while restriction in the levator scapula often causes pain when looking to the same direction. However, sometimes all three of these muscles can become spasmed, making it very difficult to turn the neck in any direction without considerable pain.

And it is not just the muscles which are involved with neck pain from a head-forward posture. The strain in the posterior neck from the additional load signals fibroblasts to produce more extracellular matrix to support this area. Fibroblasts are specialized cells that produce the building blocks of fibrous connective tissue, such as collagen fibers and a sticky, syrupy substance called proteoglycans (a protein-carbohydrate based molecular structure). Prolonged strain (such as years of bracing against the extra weight of having the head forward) stimulates production of this extra material which can be easily felt as dense, ropy, fibrous bands in the upper back and neck region. It is the body’s attempt to add more support to a region that has additional demands placed on it. Local massage, acupuncture, or other treatments applied directly to the painful tissue may temporarily help make this dense, stagnant tissue feel better, but the posture as a whole needs to be addressed if there is to be any hope of long-lasting relief.

Cervical facet joint referral patterns.
Image from: Osteoarthritis of the Spine:
The Facet Joints, Gellhorn, A.C. et al
Nature Reviews Rheumatology 9, April 2013
Facet joint syndrome: This involves a degeneration of the vertebral facet joints, which is usually secondary to degeneration of the intervertebral discs. Cervical disc degeneration is usually exaggerated whenever there is long term hypomobility (limited movement) of cervical spine. While the outer part of the intervertebral disc has a blood supply, the inner part does not and requires nutrition and fluids via diffusion from the outside. So, with any limited movement patterns that persist for a long time, the discs suffer. As one of my tai chi instructor states, “Motion is Lotion,” and this is definitely true for the spine. In addition to the discs, the synovial, freely moveable (at least they should be) joints of the spine can become degenerative and lead to pain, which can affect the neck but can also refer to the head and, even more commonly, between the shoulder blades. This is a commonly overlooked source of pain and patients with a head-forward posture are much more predisposed to it.

Facets joints are the synovial joints between adjacent vertebrae. They can become degenerative and painful with osteoarthritis of the spine. In a head forward posture, the upper cervical facets are often in a closed position while the lower facets are in an open unstable position. Both situations can aggravate the joints and lead to referred pain. This image is from Kapandji's Physiology of Joints.

Splenius capitis (close to GB-20) and splenius cervicis
(at extrapoint Bailao) TrP referral patterns.
Image from Travell and Simons' Myofascial Pain and
Dyfunction: A Trigger Point Manual.
Tension headaches: With cervical (neck) flexion and capital (head) extension, the posterior cervical muscles are in a shortened position, especially the muscles referred to as the suboccipitals. These four deep upper cervical muscles are very common causes of referred pain into the head, contributing to tension headaches. With the movement of the head forward, the eyes would be looking toward the ground if not for these muscles tightening to lift the head, placing the occiput into an extended position relative to the top of the cervical spine. Other muscles, such as the upper trapezius, splenius capitis, splenius cervicis, and sternocleidomastoid (SCM) are also negatively impacted and common contributors to tension headaches.

Nerve impingements and entrapments: Since disc health is affected by head-forward posture, it can play a role in spinal nerve impingement.  In addition, thoracic outlet syndrome (another type of entrapment of neural structures) is often seen with a head-forward posture. Both of these can radiate pain into the upper extremities and be causes of pain in the arms, elbows, forearms or hands.
Thoracic outlet syndrome involves an entrapment of the brachial plexus, which is the bundle of nerves that exit from the neck and travel to the arms. The brachial plexus can be entrapped as it travels between the anterior and middle scalene muscles (two anterior neck muscles which are shortened in a forward-head posture), between the clavicle and ribcage, and between the pectoralis minor muscle and the ribcage. The head-forward posture is often a contributing factor to all of these, especially as the entire shoulder girdle is involved (more on this in the next post).

Jaw tension: a head-forward posture places the mandible (lower jaw bone) in a position which stresses and tightens the muscles of the jaw. The position of the head places anterior neck muscles such as the suprahyoids and infrahyoids in an overstretched position. These muscles attach to the mandible and pull down on the lower jaw bone. The muscles of mastication (chewing), such as the masseter, reflexively tighten to hold the jaw close. They then develop trigger points which put pressure on the temporomandibular joint (TMJ).

Shoulder and other problems: Part 2 of this post will discuss the relationship of the balance of the cervical spine to the shoulder girdle. Because these are so intimately tied to each other, shoulder dysfunction such as supraspinatus tendinopathy, bicipital tenosynovitis, infraspinatus and subscapularis myostrain, and other conditions are often made worse by the strain of a head-forward posture. As we explore the sinew channel relationship described in Chinese medicine, this neck-shoulder girdle relationship will become even more apparent.

Image from Startle as a Paradigm 
for Malposture, by Pierce, F. et al 
Perceptual and Motor Skills, 1964
A)     Patient standing upright
B)      Door closes loudly and 
startles patient. Notice the 
shortening along the front 
of the body 
In addition to shoulder dysfunction, head-forward posture can contribute to other problems elsewhere in the body. This could become a very complex analysis, so I will not give a complete list. However, I will mention some interesting research that explored hamstring flexibility in relation to the suboccipital muscles (which extend the joint between the occiput and top of the cervical spine). This research measured hamstring flexibility and then split the subjects into two groups. Members of one group performed hamstring stretches; members of the other performed stretching to the suboccipital muscles. Surprisingly, the group that received stretching for the suboccipitals alone had a greater increase in hamstring flexibility (13%) than the group receiving hamstring stretches alone (9%). The reason likely has to do with the high concentration of muscle spindles present in the suboccipital muscles and, due to this, the fact that they have such a strong influence on tone throughout the musculature of the back, especially at the hip joint. Consider what happens when someone is startled, and the typical startle response observed. The firing of the suboccipitals might be reflexively tied to the firing of the hamstrings which assists in extending the hip joint. This, along with the shortening in the front of the body, would effectively protect the vulnerable organs.

For acupuncturists, it is worth reexamining the Urinary Bladder sinew channel and noting that it does bind to the occiput, and, therefore would include the suboccipital muscles. Looking for a head-forward posture and addressing shortened suboccipitals would be a worthwhile strategy, not only when treating local dysfunction, but with any strain pattern affecting the Urinary Bladder sinew channel. Addressing this pattern would help focus the selection of effective points to treat according to the principle of “selecting points above to treat below.”

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