Articular Facet Of The Head Of The Rib

Description

Articular facet of the head of a typical rib occupies the medial end of the rib, where the capitulum forms a wedge-shaped surface separated into superior and inferior demifacets by the crest of the head. The superior facet aligns with the inferior costal demifacet of the numerically corresponding thoracic vertebra, while the inferior facet meets the superior costal demifacet of the vertebra below, with the intervertebral disc lying immediately between these two articulation levels. Surrounding bone of the rib head curves laterally into the neck, so the facet plane reads as a compact, slightly convex joint surface at the proximal terminus of the rib. Joint geometry matters. These demifacets define the classic costovertebral joint arrangement of ribs 2 through 9, a frequent teaching point because it explains why the crest anchors the intra-articular ligament to the intervertebral disc and why degenerative disc height loss can change rib excursion mechanics and provoke posterior thoracic pain. Osteophytes at the thoracic vertebral bodies, inflammatory enthesopathy (including ankylosing spondylitis), or subtle malalignment after vertebral compression fracture can all alter contact across the superior versus inferior facets, and that asymmetry is easier to explain when the ridge and two facet fields are isolated and well lit. The wedge form also helps learners distinguish a typical rib head from the single-facet heads seen in ribs 1, 10, 11, and 12. Use this illustration in thorax and vertebral column anatomy labs to correlate rib numbering with thoracic vertebral demifacets, and in orthopaedic or radiology teaching files to annotate costovertebral arthrosis, rib head fracture patterns, and posterior thoracic pain generators adjacent to the T-spine. Anatomical accuracy verified by SciePro's Medical Advisory Board.