The neck is an upward extension of the spine beyond the body, designed to support and serve the needs of the head. It is amazingly designed and highly engineered so its underlying very complex function goes on in the background without us having to think about it. We can move and stop the motion of our heads very quickly, placing it very precisely within its very large range of motion, despite its weight and the leverage of its position. The head bears most of our very important sensory organs so the neck's job is to put the head where it can perform its sensory function best.
The structure of the neck region consists of discs, muscles, joints, bones and ligaments but it is worth ensuring that we do not forget the nervous components which are so important up here close to the brain. The comprehensive nervous control of the area facilitates movement, accepts incoming information for movement planning and controls circulatory responses. The function of the cervical spine is a compromise between the subtle control mechanisms needed and the requirement to provide as much range of joint movement as possible.
Mechanical symptoms are the initial and obvious symptoms from the neck, with postures and activities causing the pain to vary in severity. Loss of range of motion and pain symptoms of various kinds are typical complaints but other problems related to the neck can be difficulties with balance, disturbed vision, dizziness, headaches, mental stresses and muscle weakness. If the physiotherapist can settle the muscle and joint dysfunctions in the neck then all the other symptoms can be positively affected also.
Large degrees of joint mobility are present in the cervical spinal region and this is partly made possible by the greater thickness of the intervertebral discs in the cervical region compared to the other spinal areas. Larger ranges of movement are possible with thicker discs, and the facet joints are structurally larger than similar joints in any other spinal areas. The large gliding motions which are possible in the neck allow its high levels of mobility in the compromise between mobility and stability in the spine.
The vertebrae in the upper neck, particularly the two upper ones called the atlas and axis, are of a very different shape to the remaining neck vertebrae. These bones are specially designed to work with the movements and stability of the skull and the C1 and C2 articulation is a structure well suited to rotatory movements and makes up much of the neck's rotatory ability. The neck has a very great range of motion with the typical movements of side flexions, flexion, extension and rotations, enabling us to position our faces in a varied combination of positions and angles to allow us to do what we need to do.
The neck is helped in its mobility and stability by the thoracic spine beneath it, which allows an increased range of the neck and without which the neck would have to cope with much increased loads at each end of its span where it meets different structures such as the thorax and the skull. The head sits on top of the long tower of the cervical spine with the stabilising guy ropes of the muscles allowing the head to be placed in space accurately without shifting repeatedly. The head is a weighty object and is placed anterior to the centre of gravity, forcing the muscular stabilisers to require endurance and strength to keep the head still so our sense organs can function.
The flexor muscles of the neck are at the front and do not have a very difficult job, only working hard when we get up from lying on the back. The extensor muscles, however, are designed to hold our heads up and have to do it for many hours a day, frequently for the whole day. They only go off line when we lie down or start to nod off in a train for example, as our heads fall forward without the support of the extensors. Looking at the neck muscles it can be seen that although they may balance the neck there is significant downward compressive forces produced on the neck structures.