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 neck is a delicately functioning unit and this precise control is disturbed by muscle spasm which decreases its coping with unexpected forces. The neck shows an increased vulnerability to sudden applied forces when its muscles continue contracting beyond their allotted times. Guarding of the neck and self-limitation of movements occurs as the neck becomes increasingly painful and stiff, with the range of arm movements carefully limited. How the neck posture relates to the posture and mobility of the thoracic spine causes significant after affects for pain problems in the neck under stress.

A lack of thoracic kyphosis can mean that the thoracic spine approaches its junction with the cervical spine above it in too vertical a position, forcing the neck to adopt a correspondingly more vertical posture than normal. The loads the neck bears are usually spread between the discs and the facet joints by the normal lordosis and if this is lost then increased loads may be thrown onto the discs, causing increased degenerative changes within them. The opposite, where an increased thoracic curve forces a correspondingly increased neck curve, is countered either by neck or lumbar extension.

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.

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.