The Cervical Spine ” Part Two
Facet joints are very irritable, which means when they are injured or inflamed they very quickly cause pain in response to initially abnormal, but later to normal, stresses. This causes aching and local tender spots in the neck, shoulder areas, over the shoulder blades and upper arms. Pain also leads to secondary muscle spasm which compresses the joints together further and amplifies the stresses and the pain. Muscle spasm can be very dominant in some neck problems and can easily be felt as tough, hard muscular contraction which is permanently present when the neck is under load.
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.
Many different ways of injuring the neck are possible but usually involve some straight up and down compression/tension forces and/or shearing or twisting forces which are more lateral in direction. Such injuries damage the outer walls of the intervertebral discs and this sets off degenerative processes in the disc which follow from the pain, muscular abnormalities of over and under activity, range of movement limitation and poorer disc nutrition. The extension muscles of the neck can contract more continuously and forcefully, pressuring the vertebral levels together abnormally. A thinned and degenerate disc may lead to a stiff segment but can also develop excessive mobility as its water content has decreased and its stability reduced.
When a segment suffers degenerative changes bony outgrowths can appear at its margins along the ligaments, outgrowths known as osteophytes. Segmental levels with significant movement abnormalities will tend to show osteophytic changes, perhaps reflecting an attempt by the body to give increased segmental stability by building a bony bridge along the ligament or disc wall between the segments. The nerve roots in the neck or the back can be impinged upon by osteophytes which can cause severe arm or leg pain, requiring surgery. Surgical management is not a regular approach to most osteophytes which may well be asymptomatic.
The facet joints of the neck are now vulnerable once the affected segment has stiffened with degenerative changes. Narrowing of the discs causes the facet surfaces to suffer increased contact forces as the segment closes down on itself. The movements which should be performed by the gradually more abnormal and stiff facet are passed onwards to other parts of the spinal system above or below the stiff segment. Facet joints which are normal can then start to suffer from the abnormal forces and change.
