Quick Facts
Location: Vertebral column.
Bone Type: Irregular bone.
Key Features: Vertebral body, laminae, pedicles, superior and inferior articular processes, and transverse and spinous processes.
Articulates With: Seventh cervical and second thoracic vertebrae, first and second ribs.
Arterial Supply: Posterior intercostal arteries.
Related parts of the anatomy
Key Features & Anatomical Relations
The first thoracic vertebra (vertebra T1) is the smallest of the twelve thoracic vertebrae of the vertebral column. Although its general morphology is typical of the thoracic vertebrae, the first thoracic vertebra presents some transitionary features, similar to the seventh cervical vertebra. It is classified as an irregular bone and includes the following bony features:
- parts: vertebral body, laminae, pedicles, superior and inferior articular processes, and transverse and spinous processes;
- surfaces: superior and inferior intervertebral surfaces, superior and inferior annular epiphyses, and vertebral arch;
- landmarks: superior and inferior vertebral notches, superior and inferior articular facets, and superior, inferior, and transverse costal facets.
More information regarding these and other bony features can be found in the Parts, Surfaces, and Landmarks tabs for this bone.
The first thoracic vertebra is located:
- superior to the second thoracic vertebra;
- inferior to the seventh cervical vertebra;
- medial to the first and second ribs.
It articulates with the:
- seventh cervical and second thoracic vertebra at the intervertebral symphyses and zygapophyseal joints;
- first and second ribs at the costovertebral joints.
Ossification
Ossification of all thoracic vertebrae occurs at eight ossification centers, these are found in the:
- vertebral body, which appears in utero during the second to fourth months;
- right and left halves of the vertebral arch, with one center found in each, which appear in utero during the third month;
- right and left transverse processes, with one center found in each, which appear during puberty;
- spinous process, which appears during puberty;
- superior and inferior annular epiphyses, with one center found in each, which appear during puberty.
The ossification centers for the right and left halves of the vertebral arch fuse with each other during the first year after birth. The vertebral arch fuses with the vertebral body during the third year. The remaining centers fuse with the vertebral arch and body during early adulthood (Standring, 2016).
Variations
In some individuals:
- the spinous process of first thoracic vertebra may be more prominent than that of the seventh cervical vertebra;
- the superior costal facet of the first thoracic vertebra may be present as a demifacet and not a complete facet, in instances where the first rib articulates with both the first thoracic and seventh cervical vertebrae;
- the pedicles of thoracic vertebrae can display significant morphological variation;
- the transverse processes may fail to ossify (Tubbs, Shoja and Loukas, 2016).
Surface Anatomy
The spinous process of the first thoracic vertebra can be palpated, especially during flexion of the neck and trunk.
List of Clinical Correlates
- Fracture
- Osteoporosis
- Spinal stenosis
- Scoliosis
- Spondylosis
- Spondylolisthesis
- Spondylolysis
- Butterfly vertebra
- Spina bifida
References
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.
