However, T5-T8 have the greatest rotation ability of the thoracic region. The positioning of the ribs and spinous processes greatly limits flexion and extension of the thoracic vertebrae. The length of the transverse processes decreases as the column descends. For example, the inferior demifacets of T4 and the superior demifacets of T5 articulate with the head of rib 5. They are positioned so that the superior demifacet of the inferior vertebrae articulates with the head of the same rib that articulates with the inferior demifacet of the superior rib. The demifacets are bilaterally paired and located on the superior and inferior posterolateral aspects of the vertebrae. There are six facets per thoracic vertebrae: two on the transverse processes and four demifacets-the facets of the transverse processes articulate with the tubercle of the associated rib. The primary characteristic of the thoracic vertebrae is the presence of costal facets. T5-T8 tend to be the most “typical” because they contain features present in all thoracic vertebrae. Typical thoracic vertebrae have several features distinct from those typical of cervical or lumbar vertebrae. Lastly, two transverse processes project laterally from the vertebral arch in a symmetric fashion. The spinous process projects posteriorly and inferiorly from the vertebral arch and overlaps the inferior vertebrae to various degrees, depending on the region of the spine. These maintain vertebral alignment, control the range of motion, and are weight-bearing in certain positions. The point at which superior and articular facets meet is known as a facet, or zygapophyseal, joint. A typical vertebra also contains four articular processes, two superior and two inferior, which contact the inferior and superior articular processes of adjacent vertebrae, respectively.

The arch consists of bilateral pedicles, cylindrical segments of bone that connect the arch to the body, and bilateral lamina, bone segments form most of the arch, connecting the transverse and spinous processes. The arch, along with the posterior aspect of the body, forms the vertebral (spinal) canal, which contains the spinal cord. The vertebral body consists of a trabecular bone, which contains the red marrow, surrounded by a thin external layer of compact bone. Vertebral bodies increase in size from superior to inferior. The body bears the majority of the force placed on the vertebrae. Typical vertebrae consist of a vertebral body, a vertebral arch, as well as seven processes. Thoracic vertebrae are unique in that they have the additional role of providing attachments for the ribs.

The thoracic vertebrae, as a group, produce a kyphotic curve. The intervertebral discs, along with the laminae, pedicles, and articular processes of adjacent vertebrae, create a space through which spinal nerves exit.

The thoracic region contains 12 vertebrae, denoted T1-T12. The intervertebral discs are responsible for this mobility without sacrificing the supportive strength of the vertebral column. The spine has several major roles in the body that include: protection of the spinal cord and branching spinal nerves, support for thorax and abdomen, and enables flexibility and mobility of the body. It extends from the skull to the coccyx and includes the cervical, thoracic, lumbar, and sacral regions. Vertebrae, along with intervertebral discs, compose the vertebral column or spine.

Thoracic vertebrae vertebral arch