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M01.05.007 Thoracic Spine
The thoracic spine is the second segment of the vertebral column, located between the cervical and lumbar segments. Comprising 12 vertebrae, separated by intervertebral discs, it forms part of the thoracic cage along with the sternum and ribs. This structure protects vital organs such as the heart, lungs, and esophagus.
This article provides an in-depth understanding of the anatomy of the thoracic vertebrae, including their characteristic features, joints, ligaments, and clinical correlations.
Characteristic Features
The thoracic vertebrae are distinct from other vertebrae due to the following features:
| Feature | Description |
|---|---|
| Vertebral Body | Heart-shaped. |
| Demi-Facets | Present on sides of vertebral bodies, articulating with rib heads. |
| Costal Facets | Located on transverse processes (T1–T10) for articulation with rib tubercles. |
| Spinous Processes | Long, slant inferiorly, providing increased protection to the spinal cord. |
Superior and Inferior Costal Facets
- Located on the sides of vertebral bodies.
- Cartilage-lined depressions for articulation with rib heads:
- Superior facet: Articulates with the head of the adjacent rib.
- Inferior facet: Articulates with the head of the rib below.
Atypical Thoracic Vertebrae
| Vertebra | Unique Features |
|---|---|
| T1 | Superior facet is a whole facet (articulates with the first rib). |
| T10 | Single pair of whole facets across vertebral body and pedicle (articulates with the 10th rib). |
| T11, T12 | Single pair of entire costal facets located on the pedicles. |
Joints
The joints of the thoracic spine are divided into two categories:
1. Joints Present Throughout the Vertebral Column
- Intervertebral Disc Joints:
- Type: Cartilaginous (symphysis).
- Join adjacent vertebral bodies with fibrocartilage.
- Facet Joints (Zygapophysial Joints):
- Type: Synovial.
- Formed by articulation of superior and inferior articular processes.
2. Joints Unique to the Thoracic Spine
| Joint | Description |
|---|---|
| Costovertebral Joint | Articulates rib head with: |
- The superior costal facet of the corresponding vertebra,
- Inferior costal facet of superior vertebra,
- Intervertebral disc.
| Costotransverse Joint | Articulates transverse process of vertebra with rib tubercle (absent in T11 and T12). |
Ligaments
Ligaments Throughout the Vertebral Column
| Ligament | Function |
|---|---|
| Anterior Longitudinal | Covers anterior vertebral bodies and discs. |
| Posterior Longitudinal | Covers posterior vertebral bodies and discs. |
| Ligamentum Flavum | Connects adjacent vertebral laminae. |
| Interspinous | Connects adjacent spinous processes. |
| Supraspinous | Runs along tips of spinous processes (forms nuchal ligament in the cervical region). |
Ligaments Unique to the Thoracic Spine
| Ligament | Function |
|---|---|
| Radiate Ligament | Connects rib head to vertebrae and intervertebral disc. |
| Costotransverse Ligament | Connects rib neck to transverse process. |
| Lateral Costotransverse | Extends from transverse process to rib tubercle. |
| Superior Costotransverse | Runs from rib neck to transverse process of superior vertebra. |
Clinical Correlation: Thoracic Kyphosis
- Definition: Excessive curvature of the thoracic spine causing a “hunched” appearance.
- Etiology:
- In Adolescents: Poor posture, Scheuermann’s kyphosis, or vertebral fusion.
- In Adults: Osteoporosis leading to weakened vertebrae, resulting in curvature.
| Cause | Description |
|---|---|
| Scheuermann’s Kyphosis | Abnormal vertebral wedge shapes in adolescents. |
| Osteoporosis | Loss of bone mass weakens spinal support in older adults. |
Points to Remember
- The thoracic spine consists of 12 vertebrae that form part of the thoracic cage.
- Unique features include heart-shaped vertebral bodies, demi-facets, and long spinous processes.
- The thoracic vertebrae articulate with ribs through costovertebral and Costotransverse joints.
- Numerous ligaments provide stability, some specific to thoracic anatomy.
- Thoracic kyphosis is a clinically significant condition often linked to osteoporosis.
References
- Anatomy of the Thoracic Spine. (Insert detailed references here).
- Clinical Resources for Spine Pathologies.