Anatomy Lesson: Spinal or Vertebral Column
The Spinal Column is also called the Vertebral (ver-tea-brawl) Column. It starts at the skull and extends into the pelvis (hip area). The column contains 33 bones termed vertebrae (ver-tea-bray). Vertebrae is plural, vertebra is singular. The vertebrae are stacked on top of each other. The spine has five regions. See the table below.
|Region||# of Vertebrae||Body Area||Abbreviation|
C1 - C7
T1 - T12
5 or 6
L1 - L5
S1 - S5
The Atlas and Axis
The cervical spine is divided into two parts; upper (C1 and C2) and lower (C3 - C7). C1 is termed the Atlas and C2 is called the Axis. Also, there is a flat bone that forms at the back of the head. This bone is called the Occipital Bone (awk-sip-it-tull). C3 through C7 have no other names.
The Atlas is the first cervical vertebra, abbreviated C1. This vertebra supports the skull. It looks different than other vertebrae. The Atlas is a ring-shaped bone.
The Axis is the second cervical vertebra, or C2. It looks like a dull tooth and sticks upward into the ring of the Atlas. Part of the Axis is called the "dens" (Latin for "tooth"). The dens or tooth extends up from the C2 vertebral body and joins with the inside of the C1 ring. The Atlas and Axis allow the head to turn from side to side.
The Spinal Column's Duties:
Spinal cord and nerve roots
|Base for Attachment||Ligaments
|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 the above
|Other||Bones product red blood cells
Vertebrae carry much of the body's weight with the help of the discs, which are the soft tissue cushions between these vertebrae. The cervical vertebrae are the smallest - the lumbar are the largest.
Upper body weight is distributed through the spine to the pelvis. The natural curves in the spine (kyphotic and lordotic) distribute body weight and stress during movement.