The vertebrae

Anatomy of a Vertebra

Vertebrae have specific characteristics depending on their location in the spine. However, they all share a similar basic structure, with the exception of the first two cervical vertebrae and the sacrum.

The Vertebral Body: Covered with strong cartilaginous bone, it has a spongy core that allows for vascularization.
Interbody cages or discs prostheses are placed on the vertebral body.

The Posterior Arch: Composed of the pedicles, laminae, and facet joints. The pedicles are the structures on which the screws used in posterior fusion systems are inserted.

Anatomy of the Vertebral Column

The vertebral column, also called the spine, is composed of a stack of vertebrae separated by intervertebral discs.
It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae. 
The vertebrae are named and numbered from top to bottom. The bones of the sacrum and coccyx result from the fusion of several vertebrae.

The Cervical Vertebrae

The 7 cervical vertebrae (C1 to C7) are the smallest and most mobile. The atlas (C1) and the axis (C2) have a particular shape. 
The Atlas (C1) acts as a pivot on which the skull directly rests. This vertebra allows the movement of the head back and forth. 
The Axis (C2), facilitates the rotation of the head from left to right.

The Thoracic Vertebrae

The 12 thoracic vertebrae (T1 to T12) are of intermediate size and less mobile, with articular facets for the ribs, heart-shaped bodies, and long spinous processes angled downward.

The lumbar vertebrae

The 5 lumbar vertebrae (L1 to L5) are the most massive with the largest vertebral bodies to support the body's weight. Their spinous processes are short and horizontal. Their mobility is intermediate between that of the cervical and thoracic vertebrae.

The Sacrum

The sacrum is a single bone formed by the fusion of 5 sacral vertebrae (S1 to S5), located at the base of the spine. It articulates with L5, the coccyx, and the iliac bones of the pelvis. Unlike other vertebrae, the sacral vertebrae are immobile.

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