Whiplash

Anatomy

What parts of the spine are involved?

The human spine is made up of 24 spinal bones, called vertebrae. Vertebrae are stacked on top of one another to form the spinal column. The spinal column is the body's main upright support.

The cervical spine is formed by the first seven vertebrae referred to as C1 to C7. The cervical spine starts where the top vertebra (C1) connects to the bottom edge of the skull. The cervical spine curves slightly inward and ends where C7 joins the top of the thoracic spine. This is where the chest begins.

A bony ring attaches to the back of the vertebral body. When the vertebrae are stacked on top of each other, the rings form a hollow tube. This bony tube surrounds the spinal cord as it passes through the spine. Just as the skull protects the brain, the bones of the spinal column protect the spinal cord.

As the spinal cord travels from the brain down through the spine, it sends out nerve branches between each vertebrae called nerve roots. The nerve roots that come out of the cervical spine form the nerves that go to the arms and hands.

Two spinal nerves exit the sides of each spinal segment, one on the left and one on the right. As the nerves leave the spinal cord, they pass through a small bony tunnel on each side of the vertebra, called a neural foramen. (The term used to describe more than one opening is neural foramina.)

Each spinal segment includes two vertebrae separated by an intervertebral disc, the nerves that leave the spinal cord at that level, and the small facet joints that link each level of the spinal column.

An intervertebral disc is made of connective tissue. Connective tissue is the material that holds the living cells of the body together. The disc is a specialized connective tissue structure that separates the two vertebral bodies of the spinal segment. The disc normally works like a shock absorber. It protects the spine against the daily pull of gravity. It also protects the spine during activities that put strong force on the spine, such as jumping, running, and lifting.

An intervertebral disc is made up of two parts. The center, called the nucleus, is spongy. It provides most of the ability to absorb shock. The nucleus is held in place by the annulus, a series of strong ligament rings surrounding it. Ligaments are strong connective tissues that attach bones to other bones.

There are two facet joints between each pair of vertebrae--one on each side of the spine. The surfaces of the facet joints are covered by articular cartilage. Articular cartilage is a smooth, rubbery material that covers the ends of most joints. It allows the bone ends to move against each other smoothly, without pain. The alignment of the facet joints of the cervical spine allows freedom of movement as you bend and turn your neck.

Related Document: Sanctuary for the Physical Arts Guide to Cervical Spine Anatomy

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