Thoracic VertebraeEdit

The thoracic vertebrae form the middle segment of the spine, bridging the gap between the cervical (neck) and lumbar (lower back) regions. In humans and many other vertebrates, there are twelve of them, designated T1 through T12. They are uniquely integrated with the rib cage, offering a stable scaffold for the thoracic cage while protecting the spinal cord as it traverses the vertebral canal. Together with the ribs and sternum, they help form the Rib cage and play a central role in protecting vital organs and enabling a range of postures and movements.

The thoracic region stands apart from the cervical and lumbar regions in both structure and function. It bears more rigid constraints because the ribs anchor to it, which in turn affects how this part of the spine moves. The general architecture—bodies, vertebral arches, and processes—supports attachment of muscles and ligaments that maintain posture, stabilize the trunk, and permit controlled rotation and lateral bending. At the same time, the presence of rib connections reduces the extent of flexion compared with the cervical region and limits extreme bending, helping to protect the thoracic contents and the spinal cord housed within the Vertebral column.

Anatomy and terminology

Number, location, and overall plan

The thoracic vertebrae occupy the portion of the spine that lies between the cervical vertebrae above and the lumbar vertebrae below. They are arranged in a consistent sequence from T1 to T12, and each vertebra interfaces with a pair of ribs through costal joints. The thoracic spine is part of the broader Vertebral column and participates in forming the Thoracic cage with the ribs and sternum.
The typical thoracic vertebra shares several core features with other vertebrae, including a vertebral arch enclosing the vertebral foramen, a vertebral body, and a series of processes that provide leverage and muscle attachment points. The vertebral body tends to be more heart-shaped in the upper thoracic levels, and the vertebral arch projects posteriorly to create a protective canal for the spinal cord.

Costal articulation: ribs and facets

A defining attribute of the thoracic vertebrae is their articulation with ribs. Each thoracic vertebra bears costal facets on the bodies for the heads of the ribs, and, for most of the upper thoracic levels, facets on the transverse processes for the tubercles of the ribs. These joints—the costovertebral joints and costotransverse joints—integrate the spine with the rib cage and contribute to the stability and mechanics of the thorax.
The pattern of costal facets varies along the thoracic series. In most upper thoracic vertebrae there are superior and inferior costal facets on the body, which accommodate the heads of adjacent ribs, while the transverse costal facets on the transverse processes accommodate the ribs’ tubercles. The lower thoracic levels show a simplification, and the 11th and 12th ribs (often called floating ribs) have reduced or absent transverse facets, reflecting their armamentarium of articulations. These relationships help explain how the rib cage moves during respiration and how the spine supports the chest wall.

Vertebral body, arch, and processes

The vertebral body in the thoracic region is typically smaller than in the lumbar region but larger than in the cervical region. It provides a sturdy anchor for the rib connections and for the intervertebral discs that cushion each motion segment.
The vertebral arch consists of pedicles and laminae that form the vertebral foramen, which houses the spinal cord and surrounding nerve roots. The foramina in the thoracic spine tend to be circular to oval, with the spinal canal relatively narrow in comparison to the cervical region.
The spinous processes are generally long and slender, angled downward and overlapping those of the vertebrae below. This pattern contributes to the characteristic appearance and restriction of movement in the midline of the back.
The transverse processes project laterally and provide attachment points for muscles and ligaments. In the upper part of the thoracic spine, these processes bear transverse costal facets for the tubercles of the ribs, helping to secure rib motion to spinal movement.

Facet orientation and motion

The superior and inferior articular facets (on the facets of the vertebra) align predominantly in a coronal plane. This orientation favors rotation and lateral bending more than flexion, which is consistent with the thoracic cage’s role in limiting extreme movement to protect the thoracic contents and the spinal cord.

Nerve passageways and clinical relevance

Intervertebral foramina formed between adjacent vertebrae permit the exit of the thoracic spinal nerves. These nerves contribute to the autonomic and somatic innervation of the trunk and walls of the thorax and abdomen.
The thoracic region is a site for a range of clinical considerations, from degenerative changes and disc problems to conditions like thoracic outlet issues in rare cases and juvenile or adult deformities such as kyphosis and Scheuermann’s disease. Although most spinal pathology is more commonly diagnosed in the cervical or lumbar regions, thoracic issues can produce back pain, radiculopathy, or myelopathy when nerve roots or the spinal cord is affected.

Structure and variation by level

T1 and the uppermost vertebrae show features that accommodate the first rib and its articulations, while the lower thoracic vertebrae (T9–T12) gradually transition toward lumbar-like characteristics. This transition underlines the thoracic spine’s role as a bridge between the flexible cervical spine and the more weight-bearing lumbar region.
The 12 vertebrae collectively contribute to a kyphotic curvature in the upper back, which is part of the natural alignment of the spine. This curvature interacts with the rib cage to balance structural stability with the range of motion required for posture and breathing.
Variation exists among individuals and species. Developmental biology and genetics influence the shape and size of vertebral bodies, the exact pattern of costal facets, and the robustness of the processes. In some people, minor anatomic variants can influence susceptibility to certain kinds of back pain or to how a given spine segment responds to injury or wear over time.

Development, aging, and health implications

The thoracic vertebrae arise from segmental mesenchymal precursors during embryonic development, ultimately differentiating into a series of vertebrae that pattern the mid-spine. Their formation is coordinated with the growth of the ribs and sternum to form the thoracic cage.
With aging, degenerative changes can occur in the thoracic discs and facets, leading to pain or limited mobility. Kyphosis, an exaggerated forward curvature, can develop from progressive changes in the thoracic region and may be functional or structural. When such changes cause symptoms, clinical assessment considers imaging of the spine alongside evaluation of adjacent structures like the ribs and chest wall.
Therapeutic approaches range from conservative care—rest, physical therapy, and targeted exercise—to surgical interventions in more severe cases. In decision-making, many clinicians emphasize preserving mobility and function while addressing pain and risk, a balance that often reflects broader healthcare priorities and patient preferences.