The Spine / What is The Spine?

The spine, also know as the spinal column, the vertebral column and the backbone, is often used to describe the most important part of an entity, and for good reason: it's this S-curved structure around which our ability to walk, run, and sleep is hinged. Our arms, legs, chest, and head all attach to the spine. And the spine affects and is affected by every movement we make. No back problem can be isolated from how the rest of our body functions. Because of this interdependence, only by understanding the whole body and how movements affect the spine can we approach back problems.



Spinal anatomy is truly unique in its form and function. It is designed to be incredibly strong, protecting the highly sensitive nerve roots, yet highly flexible, providing for mobility on many different planes.

However, many different structures in the spine are capable of producing back pain, including:

• The large nerve roots that go to the legs and arms may be irritated
• The smaller nerves that innervate the spine may be irritated
• The large paired back muscles (erector spinae) may be strained
• The bones, ligaments or joints themselves may be injured

Therefore, a review of spinal anatomy is important to understand the causes of back pain and evaluate treatment options. This section provides an overview of anatomical structures in the spine, including:

• The spinal structure of the vertebra
• The vertebral discs
• The spinal cord and nerve roots
• The muscles
• The ligaments
• Divisions of the spine
• The functions of the spine and what causes malfunction

This article will describe the basic spinal structure and how the intricate web of bone, tissue, and muscle maintains the basis for your ability to move through life.

In animals, body weight is distributed evenly on all four legs; dinosaurs or dog, the spine lies in a horizontal position. Animals may be afflicted with their own sets of problems, but back pain usually isn't among them. In human beings, however, the spine is held in a vertical position. Walking upright may have freed our ancestors to engage in myriad civilized activities, from sipping tea to carrying a bag of groceries, but it literally created a pain in our backs. Walking on two legs places an enormous strain on our spines.

The back is not made up of a single bone but is an engineering masterpiece, composed of donut-shaped bones called vertebrae. These irregular, spool-shaped structures are stacked one on top of the other. Each vertebra is separated by a ring of shock-absorbing cartilage. These disks make spinal movement possible.

The spine extends from the base of the skull to the tailbone. The spine or back is not made up of a single bone but is an engineering masterpiece, composed of donut-shaped bones called vertebrae. These irregular, spool-shaped structures are stacked one on top of the other. Each vertebra is separated by a ring of shock-absorbing cartilage called disks. These disks make spinal movement possible.

Your spine is divided into five sections: the cervical, the thoracic, the lumbar, the sacrum, and the coccyx. There are 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, and 3 to 5 fused vertebrae (together called the coccyx). The images below show the basic spinal structure. Each unit of the spine will be explained in further detail.

Term # of Vertebrae Body Area Abbreviation Cervical 7 Neck C1 – C7 Thoracic 12 Chest T1 – T12 Lumbar 5 or 6 Low Back L1 – L5 Sacrum 5 (fused) Pelvis S1 – S5 Coccyx 3 - 5 Tailbone None		Front & Side Views of the Spine Click to enlarge

The vertebral column is characterized by a variable number of curves. These curves are: (1) a sacral curve, in which the sacrum curves backward and helps support the abdominal organs, (2) a forward cervical curve, which develops soon after birth as the head is raised, and (3) a lumbar curve, which develops as the child sits and walks.  (see figure below).

Natural curves are important. Without these curves the spine would not have the strength and resilience to act as a shock absorber during movement. The back's curves are designed to absorb shock and to facilitate the full range of motion throughout the spinal column. The natural curves act as a coiled spring to absorb force or jarring during activity. Jogging or jumping rope would be impossible without these curves. The yielding curves are the pillars of strength, resilience, and flexibility in the spine. Nonetheless, our back's flexibility is not without its own set of problems.

Pathologic curvatures of the human spinal column are common. These conditions may be caused by weak ligaments, by poor posture habits, by disease or congenital abnormalities of the spinal column, by injury, or by spasm of the back muscles.

One well-known spinal curvature is hunchback, a humped condition of the thoracic or dorsal spine resulting from an extreme curvature of the spine. This curvature may be either a kyphosis, which is an accentuation of the normal posterior curvature, or a combination of kyphosis and extreme lateral curvature (scoliosis), which is known as kyphoscoliosis. Scoliosis alone rarely creates a hunchback appearance. Kyphosis may be mild or severe. Although most cases of kyphosis are congenital, the condition may result from spinal injury. (Before the development of effective antitubercular drugs, a hunchback condition was sometimes caused by Pott's disease, a form of tuberculosis affecting the vertebrae.) Collapse may occur in elderly people, particularly women, whose bones may become soft and brittle, causing a dorsal kyphosis. When curvature results from collapsed vertebrae, the person loses height along with developing the curvature. As a result of the spinal deformity in hunchback, the ribs become contorted, compressing or displacing the lungs and other structures within the chest cavity and thrusting the collarbone and shoulder blades into distorted positions. Deformations take place in the hips and other parts of the body in its effort to maintain balance.

Treatment for a hunchback condition is varied. A mild kyphosis can often be corrected with plaster casts and braces if diagnosed before the skeletal frame has completed its growth. Chiropractic manipulation can improve and control the musculoskeletal symptoms such as pain, achiness and loss of function as a result of the deformity. Congenital deformities cannot be cured. The malformation of the vertebrae are embryological in origin; only a certain amount of the deformity can be minimized by surgery and local manipulation. Hunchback caused by spinal disease is also only slightly amenable to surgery and local treatment. Traction, pads, and plaster-jacket supports are used in manipulative treatments, and electrical stimulation is also being studied. Scoliosis is sometimes addressed surgically by insertion of a metal rod along the spine.

The spine may also be affected by herniated or ruptured nucleus pulposus, a condition in which the posterior longitudinal ligament, lying on the forward side of the neural canal, gives way or allows passage of some of the substance of the cartilage between the vertebrae into the canal. This ruptured disk material presses on the nerve roots or the spinal cord, causing great pain, a condition known as slipped disk.

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