Learning Objective: By the end of this lesson, the learner should be able to describe the anatomy, characteristic features, articulations, and clinical relevance of the thoracic vertebrae, and identify how these structures contribute to the thoracic cage and spinal stability.:
The thoracic spine is the second segment of the vertebral column, located between the cervical and lumbar regions. It consists of twelve vertebrae (T1–T12) separated by intervertebral discs, forming the posterior part of the thoracic cage along with the sternum and ribs. This structure helps protect vital organs such as the heart, lungs, and oesophagus.
Activity:
Characteristic Features
The thoracic vertebrae possess distinct anatomical features that differentiate them from other vertebral regions:
- Heart-shaped vertebral body: Provides articulation with the rib heads.
- Demi-facets on the sides of each vertebral body: For articulation with rib heads.
- Costal facets on transverse processes (T1–T10): For articulation with the tubercles of ribs.
- Long, downward-sloping spinous processes: Overlap like shingles to protect the spinal cord from direct trauma.
Activity:
Superior and Inferior Costal Facets
- Found on the lateral aspects of vertebral bodies.
- Superior costal facet → articulates with the head of the corresponding rib.
- Inferior costal facet → articulates with the head of the rib below.
- Vertebrae T2–T9 typically have demi-facets, while others are atypical.
Atypical Vertebrae
- T1: The Superior facet is a complete facet for the 1st rib.
- T10: Has a single pair of complete facets across the body and pedicle.
- T11 & T12: Each has a single pair of facets on the pedicles only and no costotransverse joints.
Joints of the Thoracic Spine
Present Throughout the Vertebral Column
- Intervertebral joints – Between vertebral bodies; cartilaginous (symphysis type).
- Facet (zygapophyseal) joints – Between articular processes; synovial type.
Unique to the Thoracic Region
- Costovertebral joints
- Between the rib head, superior and inferior costal facets, and the intervertebral disc.
- Stabilized by the intra-articular ligament.
- Costotransverse joints
- Between the tubercle of the rib and the transverse process of the corresponding vertebra.
- Present in T1–T10, absent in T11–T12.
Ligaments of the Thoracic Spine
Common Vertebral Ligaments
- Anterior and posterior longitudinal ligaments – Run along the vertebral column, reinforcing the discs.
- Ligamentum flavum – Connects laminae of adjacent vertebrae.
- Interspinous ligament – Connects spinous processes.
- Supraspinous ligament – Connects tips of spinous processes (becomes nuchal ligament in the cervical spine).
Unique Thoracic Ligaments
- Radiate ligament of the head of the rib – Connects the rib head to the vertebral bodies and disc.
- Costotransverse ligament – Connects the rib neck to the transverse process.
- Lateral costotransverse ligament – Extends from the transverse process to the rib tubercle.
- Superior costotransverse ligament – Connects the rib neck to the transverse process above.
Clinical Relevance
Thoracic Kyphosis
- Kyphosis is an excessive curvature of the thoracic spine, giving a hunched appearance.
- Causes:
- Poor posture in youth
- Scheuermann’s disease (developmental wedging of vertebrae)
- Congenital vertebral fusion
- Osteoporosis in adults — loss of bone mass leads to collapse of vertebral bodies
- Effects: Reduced lung capacity, back pain, and cosmetic deformity.
- Management: Postural correction, physiotherapy, or surgical stabilization in severe cases.
