Costal Facets

Costal facets are smooth, flat surfaces located on the thoracic vertebrae where the ribs articulate with the spine. These facets form part of the costovertebral and costotransverse joints, enabling rib attachment and movement during respiration. They are unique to the thoracic region of the vertebral column.

Location

Costal facets are found only on the thoracic vertebrae (T1–T12). They are located on:

• The sides of the vertebral bodies (for articulation with the heads of ribs)
• The transverse processes (for articulation with the tubercles of ribs, except T11 and T12)

Types of Costal Facets

1. Superior Costal Facets (Demifacets)

• Located on the superior posterolateral aspect of the vertebral body
• Articulates with the inferior facet of the rib head (e.g., T5 superior facet articulates with rib 5)

2. Inferior Costal Facets (Demifacets)

• Located on the inferior posterolateral edge of the vertebral body
• Articulates with the superior facet of the rib head below (e.g., T5 inferior facet articulates with rib 6)

3. Transverse Costal Facets

• Found on the anterior surface of the transverse processes (T1–T10)
• Articulate with the tubercles of ribs of the same number (e.g., T5 transverse facet with rib 5)

Vertebral Levels and Facet Configuration

• T1: Has a full superior facet for rib 1 and an inferior demifacet for rib 2
• T2–T9: Each has two demifacets (superior and inferior) on the body and a transverse costal facet
• T10: Usually has a full costal facet on the body; may or may not have a transverse facet
• T11 and T12: Have a single complete facet on the vertebral body; no transverse costal facet

Function

• Allow articulation of the rib head and tubercle with the spine
• Enable rib movement during respiration (elevation and depression)
• Maintain structural integrity of the thoracic cage

Associated Joints

1. Costovertebral Joint

• Formed between the head of a rib and the demifacets of two adjacent vertebral bodies and the intervertebral disc

2. Costotransverse Joint

• Formed between the rib tubercle and the transverse costal facet of the corresponding vertebra
• Present only in T1–T10

Clinical Relevance

• Facet joint disorders: Dysfunction or arthritis can cause localized thoracic back pain
• Fractures or dislocations: Can disrupt rib articulation and impair respiration
• Surgical considerations: Important landmarks in thoracic spine surgery and thoracotomy approaches
• Radiologic landmarking: Facets are visualized in imaging to assess rib and vertebral alignment or injury