Workings Of The Human Neck-Part Two
Irritability of inflamed or injured facet joints is high in terms of easily and quickly flaring up into pain when subject to unusual stresses, but then later can react badly even to normal stresses. The typical symptoms are local tenderness and aching throughout the neck, across the shoulder blades, over the neck/shoulder area and upper arms. All this pain can cause the muscles to go into spasm which compounds the problem by facet joint compression with consequent enhancement of the pain and joint forces. Some patients have severe neck muscle spasm which presents as tight, hard muscles.
The overall delicate functioning of the neck can be badly disturbed by this muscle spasm, limiting its capacity to cope with sudden shocks. Muscles are more likely to remains contracted for longer than they should, rendering the neck more vulnerable to sudden jars and shocks. As the neck pain develops the person naturally guards their movement much more strongly which adds to the lack of normal movement as they limit arm activities. The interrelation of the thoracic and neck postures has important knock-on effects for neck pain syndromes as abnormal postures increase segmental stresses.
If the thoracic spine is much straighter than it typically is the reciprocal curves of the thorax and the neck can be lost, forcing the cervical spine to sit more vertically upon the thorax, without its typical lordosis. The lordosis distributes weight between the anterior discs and the posterior joints, preventing abnormal disc loading which can cause early degeneration and then secondary facet changes. Problems can also occur when the opposite anatomical misalignment occurs with an increased thoracic curve forcing a reciprocally increased cervical curve to maintain the face in a horizontal position.
Increased cervical and thoracic spinal curves result in a typical poor posture, particularly in sitting, of the head poking well forwards of the shoulders and trunk, requiring high levels of force to be developed in the supporting musculature of the neck to keep the head held in space. The biggest and strongest muscle is the upper trapezius and when it is working too hard it can develop local tender and painful spots which can refer pain elsewhere and are known as trigger points. The lower trapezius muscles can correspondingly become underactive, leading to a reduced level of control of the shoulder, neck and arm complex.
Neck injuries can occur in a variety of mechanisms, either the more vertical, compression like events or a sideways shearing and twisting incident. The disc outer walls are sensitive to these events and can be injured, starting the process of pain, muscular inhibition and muscular overactivity, reduced disc nutrition and loss of movement which progresses steadily to increased degenerative changes. As the pain progresses the neck extensor muscles add to the compression forces on the segments by becoming overactive, forcing the vertebrae closer together. Once a segmental disc has narrowed it may develop increased mobility rather than stiffness due to the reduction in strength of the disc unit when it loses its water content.
With a degenerate segment often comes the growth of osteophytes, bony outgrowths which appear at the joint margins and along its ligaments. Osteophytes grow at segmental levels which are suffering abnormal movement forces and may be the bodys attempt to stabilise the segment by growing bone from vertebra to vertebra along the now less effective ligaments. Osteophytes may impinge on the spinal nerves to the neck or the back, causing severe arm pain, usually in older people. However, most osteophytes are a symptom of the degenerating disc level and not a problem in themselves, rarely needing surgical attention.
The establishment of a stiff spinal segment in the neck forces the facet joints into an untenable position in terms of normal function. Compressed together by vertebral approximation secondary to disc narrowing, the facet surfaces suffer from the increased forces. The gradual joint damage reduces the movement available and this is picked up elsewhere in the spinal column, either lower down or higher up. This way previously normal joints can start to develop movement and structural abnormalities.
About the author:
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapists, physiotherapy, physiotherapists in Birmingham, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
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