Bones Of The Spine (Vertebral Column) The spine consists of 26 bones. Each of these bones are connected by a number of ligaments and provide support for the upper body. It also provides protection for the Spinal Cord. The vertebral column provides attachment points for the ribs and the muscles of the back.
The spine has 5 regions and each has varying characteristics: Cervical, Thoracic, Lumbar, Sacrum, and the Coccyx.
Cervical Vertebrae
The Cervical region consists of seven bones and smallest bones of the spine. They are numbered 1 to 7, starting from the top and working down. The first two also have another name: the Atlas (C1) and the Axis (C2). The Atlas is given its name because it carries the weight of the Skull (just as Atlas supported the heavens!).The Axis gets its name because it acts as a pivot which allows the Atlas to rotate.
Thoracic Vertebrae
The Thoracic region consists of 12 vertebrae which start out smaller, just like the Cervical vertebrae, and increase in size until they are similar to the Lumbar vertebrae. Each of these 12 bones articulate with the ribs.
Lumbar Vertebrae
The Lumbar region consists of 5 vertebrae. This region receives the most stress, which is why they are much larger. This is also the section commonly referred to as ‘The Lower Back’.
Sacrum
The Sacrum consists of five fused vertebrae. It is a triangular shaped bone that connects the two Coxal bones (Pelvis). It articulates with the fifth lumbar vertebrae (L5), the Coxal bones on each side, and the Coccyx at the bottom.
Coccyx (Tail-Bone)
The Coccyx usually consists of four fused vertebrae but can sometimes vary between three and five. It is a triangular shaped bone that offers a small amount of support for the pelvic region
A. Coccyx Also known as the 'Tail-Bone', the Coccyx consists of 3-5 fused bones.
B. Sacrum
Five fused vertebrae that form a triangular-shaped structure. The Sacrum is found at the back of the Pelvis.
C. L5
The lowest vertebra of the Lumbar spine
D. L1
The highest vertebra of the Lumbar spine
E. Intervertebral Disc
Intervertebral Discs are found between each vertebra and act as a cushion or shock-absorber. They are composed of an inner semi-fluid material and a strong outer ring of fibrocartilage.
F. C7
The lowest vertebra of the Cervical spine
G. C2 (Axis)
The second Cervical vertebra, it has a vertical projection called the Odontoid Process which allows the Atlas (C1) to rotate.
H. C1 (Atlas)
The highest of all vertebra, the C1 (Atlas) articulates with the Skull.
I. T1
The highest vertebra of the Thoracic spine
J. T12
The lowest vertebra of the Thoracic spine
K. Transverse Process
These lateral extensions form each vertebra provide attachment sites for muscles that move the spine and ligaments that stabilize it.