part of part of Homo sapiens thoracic vertebra 9 zone of bone organ transverse costal facet of ninth thoracic vertebra 2026-03-19T00:00:00Z A zone of bone organ located on the anterior surface of the transverse process of the ninth thoracic vertebra, articulating with the tubercle of the ninth rib at the costotransverse joint. T9 represents the lower limit of the typical transverse costal facet pattern; below this level the transverse processes diminish and the facets become vestigial or absent. David Osumi-Sutherland