How the neck is built

The neck is the most mobile part of the spine. It lets the head nod, tilt and turn, and it carries the head's weight all day. It is also a busy crossing point for nerves, blood vessels, the windpipe and the gullet. This page explains the parts of the neck that matter most in conversations about neck pain.

The cervical vertebrae

The bones of the neck form the cervical spine. The American Academy of Orthopaedic Surgeons, in its OrthoInfo page on neck pain, describes the cervical spine as the small vertebrae that begin at the base of the skull and form the neck. Compared with the vertebrae of the lower back, they are small and light, which suits their job of carrying the head rather than the whole upper body.

The top two are shaped quite differently from the rest. The first, called the atlas, is a ring that cradles the skull and allows the nodding movement of "yes". The second, called the axis, has a peg of bone that the atlas pivots around, allowing much of the turning movement of "no". The vertebrae below them are more alike, stacked with discs between them and linked at the back by small facet joints.

Discs and joints

OrthoInfo explains that the bony vertebrae, along with ligaments that act rather like thick rubber bands, give the neck its stability, and that flexible intervertebral discs between the vertebrae act as shock absorbers when you walk or run. The same page describes how cervical discs change with age: they lose height and water content, dry out and weaken, and may begin to bulge. When the outer rim of a disc weakens, the disc may press on the spinal cord or on a nerve root. The facet joints at the back of the neck can develop arthritis-type changes over time too, and OrthoInfo groups these long-term changes under the terms "wear and tear", cervical spondylosis, or arthritis of the neck.

The spinal cord and nerve roots

The spinal cord runs from the base of the skull down through the canal formed by the vertebrae. In the neck, pairs of nerve roots branch out through openings between the vertebrae and travel to the shoulders, arms and hands. OrthoInfo explains that these roots carry messages between the brain and the rest of the body. That is why a problem in the neck can be felt as pain, pins and needles, numbness or weakness in an arm or hand, and why those symptoms are worth describing carefully to a health care provider.

Muscles of the neck

Layers of muscle surround the cervical spine. Deep, small muscles link neighbouring vertebrae and fine-tune the position of the head. Larger muscles run from the skull and neck to the collarbones, shoulder blades and upper back, turning and tilting the head and helping to hold the shoulders in place. Because the head is heavy and usually sits slightly in front of the spine, the muscles at the back of the neck are working much of the time simply to keep it balanced, and they work harder the further the head drifts forward.

MedlinePlus's overview of neck injuries and disorders notes that any part of the neck, including muscles, bones, joints, tendons, ligaments or nerves, can cause neck problems, and that muscle strain or tension, often from overuse such as long spells at a computer, is a common cause.

Why the neck is vulnerable

OrthoInfo sums up the trade-off: the neck has a significant amount of motion and supports the weight of the head, but because it is less protected than the rest of the spine, it can be vulnerable to injury. The mid back is braced by the ribs and the lower back by thick muscles and the pelvis; the neck has neither. A sudden jolt, such as a car being struck from behind or a fall onto the head or shoulders, can move the neck faster and further than the tissues are used to.

Neighbouring structures

The neck is crowded. In front of the spine lie the windpipe and gullet; at the sides run large blood vessels to and from the head; glands and lymph nodes sit beneath the skin. This is one reason why neck pain that comes with a lump, swollen glands, difficulty swallowing or breathing, or a fever is treated as more than a muscle problem. The When to see a doctor page lists these signs, and the neck pain page covers everyday causes of a stiff or sore neck.

Putting it together

Looking down at a phone, the head tips forward, the muscles at the back of the neck lengthen and work to hold it, and the discs and joints at the front and back of the cervical spine take a different share of the load. Turning to reverse a car rotates the upper joints while the lower neck and upper back follow. Everyday neck comfort depends on all these parts sharing the work, which is why position, breaks and variety come up so often on the posture page.