Thoracic vertebrae

The thoracic vertebrae (Latn: vertebrae thoracicae) comprise the middle portion of the vertebral column and are characterized by their articulation with ribs

All vertebrae have rib elements that are usually small parts of the transverse processes. However, in the thorax, the ribs are separate bones that articulate with the vertebral bodies and transverse processes of the associated thoracic vertebrae, forming synovial joints.

There are twelve vertebrae (T1 - T12)in the thoracic part of the vertebral column, which participates in forming the thoracic cage.

There are general features that mainly apply to the second through eighth thoracic vertebrae (T2 - T8). The first (T1) and ninth through twelfth (T9 - T12) thoracic vertebrae have specific characteristics.

General features

The body of a typical thoracic vertebra is somewhat heart-shaped when viewed from above. It is typically as broad in the anteroposterior as in the transverse direction. The vertebral body on either side presents two partial facets - superior and inferior costal demi-facets for articulation with the head of its corresponding rib and with the head of the rib below.

The pedicles of the thoracic vertebrae are directed backward and slightly upward.

The laminae are broad and thick. They overlap does of subjacent vertebrae like tiles of a roof and connect with the pedicles to surround and provide protection to the spinal cord.

The typical thoracic vertebra has a circular vertebral foramen, which is a large opening posterior to the body, forming the spinal canal through the vertebral column. The spinal canal contains and protects the spinal cord.

The intervertebral foramen is small and circular in the typical thoracic vertebra. There are two in each intervertebral level, one for the right and one for the left exiting nerve roots.

The transverse processes of thoracic vertebrae each have a transverse costal facet that articulates with the tubercle of its corresponding rib.

The spinous process of a thoracic vertebra is generally long and triangular in coronal cross-section. It projects in an oblique and downward direction, arising from the lamina and ending with a tuberculated extremity. 

The superior articular processes of the thoracic vertebrae are thin bony plates that project upward from the junctions of the pedicles and laminae.

The inferior articular processes fuse with the laminae significantly and project slightly beyond their lower borders.