The neck, also known as the cervical spine, includes the bottom of the skull and the seven small bones that it sits on top of, known as the cervical vertebrae. There are six discs that rest between each cervical vertebra. The purpose of the discs is to absorb shock in the neck.
Nerves branch out from the spinal cord through openings in the vertebrae and carry messages between the brain and the muscles. These nerves are responsible for the muscles of the upper part of the body, including the shoulder blades, shoulders, arms and hands.
The Curves of the Spine
The neck has a natural extension curvature. Dysfunction most often occurs at the lower levels of the neck where this curve transitions into the thoracic spine (middle back), which curves in the opposite direction.
The neck has both long and short muscles. Some muscles of the neck span from the base of the skull and the bottom of the front jaw down to the collar bone, ribs and middle back. The shorter muscles are deep and may only span one or two vertebral levels. Each of these muscle groups plays a different role in providing stability and mobility to the neck.
Normal Range of Motion
The neck is more mobile than the middle and lower spine, with large ranges of mobility for flexion (forward bending), extension (backward bending), side bending and rotation. This allows us to move our head in many directions and receive visual input from our surroundings and for balance. The upper cervical spine is primarily responsible for rotation, while the middle and lower cervical spine are responsible for side bending. The motions of flexion and extension are dispersed among all cervical spine levels.
The motion of the neck would not be complete without the simultaneous movement of the middle back in the same direction.
The neck's normal range of motion will vary. However, motion should feel free and there should be no pain or stiffness at the end range. Golfers should be able to move through their swing with enough motion in their neck to keep their eyes fixed on the ball without moving, as their middle back rotates below the neck and the head.