How many thoracic vertebrae are there and what is their main function?

There are 12 thoracic vertebrae. Their primary function is to articulate with the ribs via costal facets on their bodies and transverse processes, forming part of the protective thoracic cage.

What are the key features of a typical thoracic vertebra (e.g., T2–T8)?

Typical thoracic vertebrae (T2–T8) have a heart-shaped body with superior and inferior costal demifacets for rib articulation, a circular vertebral foramen, long, slender spinous processes that are directed downwards and overlapping, and transverse processes with facets for rib tubercles.

What makes T1 an atypical thoracic vertebra?

T1 is atypical because it resembles a cervical vertebra (like C7). It has a single complete superior costal facet for the first rib, an inferior demifacet for the second rib, a horizontal and prominent spinous process, and a deep superior vertebral notch.

How do T11 and T12 differ from typical thoracic vertebrae?

T11 has a single circular costal facet on the body extending onto the pedicle and no facet on the transverse process (since the 11th rib lacks a tubercle). T12 resembles a lumbar vertebra (like L1), with a costal facet more on the pedicle, three tubercles on the transverse process (mamillary, true transverse, and accessory), and no costal facet on the transverse process.

What is the anticlinal vertebra in the thoracic region and why is it significant?

T11 is the anticlinal vertebra in the thoracic region. It is significant because it marks the point where the direction of inclination of the spinous processes changes, with those above T11 sloping downward and those below sloping more horizontally.

How do thoracic vertebrae articulate with ribs?

Thoracic vertebrae articulate with ribs through costal facets located on their bodies and transverse processes. Typical vertebrae have demifacets on the body, while atypical ones (like T1, T10–T12) have variations such as single complete or large facets to accommodate specific rib attachments.

What are the distinguishing features of T9 and T10?

T9 has only a superior demifacet on the body for rib articulation. T10 has a single large costal facet on the body that encroaches onto the pedicle, making it distinct from typical vertebrae.

Thoracic Vertebrae (T1–T12) – Features & Costal Facets

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