Ligamentum intraarticulare capitis costae

The intra-articular ligament of head of rib (interarticular in older texts; ligamentum capitis costae intraarticulare) is situated in the interior of the articulation of head of rib between the superior costal facet and the inferior costal facet.

It consists of a short ligament, a band of fibers, flattened from top to bottom, attached at one end to the crest separating the two costal facets on the head of the rib, and at the other end to the intervertebral disc between the two vertebrae; it divides the joint into two cavities.

This ligament is the homologue of the conjugate ligament present in some mammals, and uniting the heads of opposite ribs, across the back of the intervertebral fibrocartilage.

In the joints of the first, tenth, eleventh, and twelfth ribs, the intra-articular ligament does not exist; consequently, there is only one cavity in each of these articulations.