The Bones of the Neck
The neck or cervical spine is made up of 7 vertebrae or bones. The top two cervical vertebrae - C1 and C2 are called the Atlas and the Axis. These bones are unique because they are shaped differently than the rest of the bones of the neck. There is no disc between C1 and C2.
The Atlas (C1) supports the head- sometimes weighing between 12 to 16 pounds ! The Atlas also supports the skull because it has two flat surfaces. The motion of flexing your head forward is actually your skull rocking back and forth on the atlas.
The Axis or C2 fits with the atlas in a special way: it has what is called the odontoid process about which the atlas rotates. The joint between the atlas and axis is a pivot type of joint. It allows the head turn from side to side. It is also called the atloaxoid joint.
There are 8 pairs of nerves that emerge from this spinal area. The lower 4 merge to form the major innervation to the arms, wrists and fingers. That is why an injury to the neck can cause pain with numbness and tingling into the arms.
Muscles of the Neck
Muscles in the cervical spine area
- There are several layers of muscles in the neck that can contribute to neck pain:
- The Trapezius: A triangular shaped muscle that is closest to the surface
- Sternocleidomastoid (SCM)
- Scalene Muscles