Our necks are our spines continuing above shoulder level so that our head can be supported and facilitated in its job. The neck is beautifully designed and engineered and performs its highly complex functions automatically without us having to give them any thought. Our heads are very heavy and placed on top of the lever which is the neck, however we can move them or stop moving them very quickly, positioning them at a very specific point within the large ranges of movement the neck can perform. The ears and eyes, some of our most vital organs of sensory input, are placed on the head and the neck has to serve their needs.
The cervical spine is a complicated structure made up of ligaments, discs, joints, muscles and bones. What are missing from this description are the vitally important and widespread nets of nerve fibres which clothe the spinal structures here. Nerve functions include the control of movement, the transmission of sensory information for biofeedback and balance and the control of circulation and other reflex responses. The neck has a difficult job to do as the very large ranges of movement it needs to provide are at odds with its precision and delicate control.
When the neck starts to give problems they are usually mechanical at least initially, in other words the symptoms vary with posture and what the person is doing physically with their neck. Neck symptoms typically include pain and loss of movement but can also cover a very long list of other symptoms such as headache, dizziness, vision disturbance, balance loss, weakness and mental difficulties. Restoration of a relative state of normality can be established by settling down the joint and other dysfunctions in the neck.
The cervical spine has a very great degree of joint mobility and part of this ability is related to the cervical discs which are very thick in comparison to the height of the neck bones. An increased thickness of disc allows greater movement to occur in the segment. Compared to the facet joints in the lumbar and thoracic spine, these joints in the neck are much larger and facilitate the significant gliding movements required in the neck. Stability is important in other spinal areas but in the neck stability is compromised in favour of mobility.
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 underlying stability of the cervical spine is aided by the thoracic spine underneath it, also providing increased mobility. Without the contribution to its ease of motion from the thorax the neck would suffer increased forces where it meets the stiffer and heavier parts at each end, the thoracic spine and the skull. The neck projects from the thoracic spine up to the exposed and heavy head, the surrounding muscles acting like guy ropes to maintain it in a stabilised position under load and without shaking. It’s a hard job as the head weighs a lot and is forward of the gravity centre so the muscular systems must have good strength and endurance to keep the head where we want it.
The neck flexor muscles, situated anterior to the neck, do not have a lot of work to do as they only really function strongly in getting up from lying down. It is a different story for the extensor muscles behind the neck as they have the job of keeping the head up for the whole day without tiring, only showing their function when we get tired in a train when sitting and our head flops forward as the extensors turn off. While balancing the forces applied to the neck and maintaining posture is their key function they also produce levels of compressive forces.
