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Vertebral Column

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The spinal column (or vertebral column) extends from the skull to the pelvis and is made up of 33 individual bones termed vertebrae. The vertebrae are stacked on top of each other group into four regions:

spine, lateral and posterior views, labeled, color

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 Tailbone None

Cervical Vertebrae (C1 – C7)


The cervical spine is further divided into two parts; the upper cervical region (C1 and C2), and the lower cervical region (C3 through C7). C1 is termed the Atlas and C2 the Axis. The Occiput (CO), also known as the Occipital Bone, is a flat bone that forms the back of the head.

Atlas (C1)
The Atlas is the first cervical vertebra and therefore abbreviated C1. This vertebra supports the skull. Its appearance is different from the other spinal vertebrae. The atlas is a ring of bone made up of two lateral masses joined at the front and back by the anterior arch and the posterior arch.

 

altas axis

Axis (C2)
The Axis is the second cervical vertebra or C2. It is a blunt tooth–like process that projects upward. It is also referred to as the ‘dens’ (Latin for ‘tooth’) or odontoid process. The dens provides a type of pivot and collar allowing the head and atlas to rotate around the dens.

Thoracic Vertebrae (T1 – T12)
The thoracic vertebrae increase in size from T1 through T12. They are characterized by small pedicles, long spinous processes, and relatively large intervertebral foramen (neural passageways), which result in less incidence of nerve compression.

 

parts of a thoracic vertebrae

1-Vertebral Body 2-Spinous Process 3-Transverse Facet
4-Pedicle 5-Foramen 6-Lamina 7-Superior Facet

The rib cage is joined to the thoracic vertebrae. At T11 and T12, the ribs do not attach and are so are called "floating ribs." The thoracic spine's range of motion is limited due to the many rib/vertebrae connections and the long spinous processes.

thoracic spine, rib cage, labeled

Lumbar Vertebrae (L1 – L5)
The lumbar vertebrae graduate in size from L1 through L5. These vertebrae bear much of the body's weight and related biomechanical stress. The pedicles are longer and wider than those in the thoracic spine. The spinous processes are horizontal and more squared in shape. The intervertebral foramen (neural passageways) are relatively large but nerve root compression is more common than in the thoracic spine.

lumbar vertebrae

Purpose of the Vertebrae
Although vertebrae range in size; cervical the smallest, lumbar the largest, vertebral bodies are the weight bearing structures of the spinal column. Upper body weight is distributed through the spine to the sacrum and pelvis. The natural curves in the spine, kyphotic and lordotic, provide resistance and elasticity in distributing body weight and axial loads sustained during movement.

The vertebrae are composed of many elements that are critical to the overall function of the spine, which include the intervertebral discs and facet joints.


Functions of the Vertebral or Spinal Column Include:

Protection
  • Spinal Cord and Nerve Roots
  • Many internal organs
Base for Attachment
  • Ligaments
  • Tendons
  • Muscles
Structural Support
  • Head, shoulders, chest
  • Connects upper and lower body
  • Balance and weight distribution
Flexibility and Mobility
  • Flexion (forward bending)
  • Extension (backward bending)
  • Side bending (left and right)
  • Rotation (left and right)
  • Combination of above
Other
  • Bones produce red blood cells
  • Mineral storage

Sacral Spine
The Sacrum is located behind the pelvis. Five bones (abbreviated S1 through S5) fused into a triangular shape, form the sacrum. The sacrum fits between the two hipbones connecting the spine to the pelvis. The last lumbar vertebra (L5) articulates (moves) with the sacrum. Immediately below the sacrum are five additional bones, fused together to form the Coccyx (tailbone).

Updated on: 01/10/13
Mary Rodts, DNP
Understanding the terminology associated with spinal problems is very important as health care providers discuss the problems and the solutions for the spinal disorder with patients and families. This article helps clarify a difficult topic.
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Intervertebral Discs

Intervertebral discs are the pillow-like cushions in between your vertebrae. They are your spine?s shock-absorbing system, helping you move more easily. See illustrations of what your discs look like and learn more about what they do for your spine.
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