Column

What is the spine?

The spine is composed of 33 bones in newborns and 26 in adults due to the fusion of the sacral and coccygeal vertebrae during development. The vertebrae protect the spinal cord and allow it to stand and bend.

The vertebrae are stacked one group on top of another in four regions:

• Cervical vertebrae (C1 – C7). The cervical spine is subdivided into two parts:
  • Upper cervical region (C1 and C2). The C1 vertebra is called the atlas and the C2 vertebra is called the axis.
  • Lower cervical region (C3 to C7).

  The cervical bones are designed to allow flexion, extension, and rotation of the head. They are smaller than the other vertebrae, thus allowing a greater amount of movement.

• Thoracic vertebrae (T1 – T12). The thoracic vertebrae increase in size from T1 to T12.
  In the chest region, the thoracic spine joins the ribs.
  The spinal canal in the thoracic region is relatively smaller than the cervical or lumbar areas. This puts the spinal cord in the thoracic area at greater risk if there is a fracture.
  The motion that occurs in the thoracic spine is primarily rotation. The ribs prevent flexion to the side. A small amount of motion occurs in forward and backward flexion.
• Lumbar vertebrae (L1 – L5). The lumbar vertebrae vary in size from L1 to L5. These vertebrae carry most of the body weight and related biomechanical stress.
  The lumbar vertebrae are large, broad and thick. The lowest lumbar vertebra, L5, articulates with the sacrum, and the sacrum attaches to the pelvis.
  The main movements of the lumbar region are forward flexion and backward extension. Flexion to the sides also occurs.
• Sacral region. The sacrum is located behind the pelvis. The sacrum is made up of five bones (abbreviated S1 to S5) fused into a triangular structure. The sacrum fits between the two hip bones that connect the spine to the pelvis. The last lumbar vertebra (L5) articulates (moves) with the sacrum.
• Coccyx. Immediately below the sacrum are five additional bones fused together to form the coccyx (tailbone).
  The spine of newborns is composed of 33 bones, that of adults of 26.

What are the functions of the spine?

Some of the functions of the spine are:

• Protection of areas such as the spinal cord, nerve roots and many internal organs.
• Support base for ligaments, tendons and muscles.
• Structural support of the head, shoulders, chest; connects upper and lower body; and balance and weight distribution.
• Flexibility and mobility
  • Flexion (forward lean)
  • Extension (leaning backward)
  • Tilt to the side (left and right)
  • Rotation (left and right)
  • Combination of the above
• Bones produce red blood cells, mineral storage…

What diseases can they suffer from?

The problems that can alter the structure of the spine or injure the vertebrae and the tissue that surrounds them can be several:

• Infections, such as vertebral osteomyelitis.
• Trauma
• Tumors
• Diseases, such as ankylosing spondylitis and scoliosis.
• Bone changes that occur with age, such as spinal stenosis and herniated discs.

Repeatedly, diseases affecting the spine often cause pain when bony changes put pressure on the spinal cord or nerves. Another effect is limitation of movement.

Treatment obviously varies depending on the disease affecting the spine, but back braces and surgery are often used.