The Costovertebral Joints
The articulations between ribs and the spine are called costovertebral joints. These joints are compound, so they have more than one pair of articulating surfaces. It means that any motion of the rib requires simultaneous action in two spacially separated joints: in the joint of the rib's head (articulatio capitis costae) and in the costotransverse joint (articulatio costotransversaria).
The importance of ligaments surrounding these joints is generally underestimated. However, the data available now suggest the leading role of these ligaments in maintaining the stability of the thoracic spine1,2, the involvement of these ligaments in developing scoliotic lesions3,4, and their potential importance in the surgical correction of scoliosis5.
Articulatio Capitis Costae & Ligaments of the Heads of Ribs
The ligamentum capitis costae radiatum usually consists of 3 bands – the upper band, attaching to the upper vertebra; the middle band, connecting the head of a rib with the intervertebral disc; and the lower band, attaching to the lower vertebra*. Please note that the radiate ligament does not surround the head circumferentially. Dorsally the joint of the rib's head is sealed by the loose and irregular fibers of the articular capsule.
Click an image to see the deeper layer – the lig. capitis costae intra-articulare, which extends from the crest of the head of rib to the intervertebral disc.
Articulatio Costotransversaria & The Lateral Costotransversal Ligament
The costotransverse joints (standard synovial joint with articular cartilages and articular gap) could be found in all ribs, except the floating one – the 11th and 12th. The lateral costotransverse ligament is the primary stabilizer of the costotransverse joint. The ligament is with the oblique course, running superiorly and laterally from the tip of the transverse process of the vertebra to the rough non-articular portion of the corresponding costal tubercle*.
Other Ligaments Stabilizing the Costovertebral Joint
Some clarification is needed here. In this section, we are trying to present some evidence-based data that may not fully match the information provided in anatomy textbooks and atlases. The ligaments presented here are:
- ‣ the lateral costotransverse (see above)
- ‣ the costotransverse
- ‣ the superior costotransverse
- ‣ the inferior costotransverse, and
- ‣ the posterior costotransverse ligaments;
The last two are not mentioned in the actual list of Anatomical Terminology but are described in the dedicated scientific literature and depicted in many anatomy atlases with original illustrations1–4.
Oblique posterior view of thorax, demonstrating the thick fibers of the costotransverse ligament joining the transverse process of the thoracic vertebrae with the neck of the corresponding rib. The last two ribs may not have such a ligament*.
The superior costotransverse ligament connects the upper edge of the rib's neck with the lower surface of the transverse process of the vertebra above. The ligament consists of two layers – the fibers of the anterior layer are directed cranio-laterally, but those of the posterior layer – cranio-medially1–3. The lateral edge of the ligament fuses with the internal intercostal membrane. The superior costotransverse ligament is rudimentary or absent on the first rib2,4.
Some authors suggest that the superior costotransverse ligament is the sole true ligament providing the lateral stability of the thoracic spine3.
Both illustrations above demonstrate the posterior costotransverse ligaments connecting the non-articular part of the tubercle of the rib with the inferior articular process and the base of the transverse process of the vertebra above. The ligaments are usually identified in the lower part of the thorax – between the 5th and 10th rib. They are believed to stabilize the costotransverse joint against the strong pull of muscles during forced expiration and with increased intra-abdominal pressure1. The origin and insertion of this ligament differ from the superior costotransverse ligament. However, there are many misleading interpretations in anatomy atlases. In some sources, the posterior costotransverse ligaments are depicted but not labeled2,3; in others – this ligament is referred as the superior costotransverse4.
The inferior costotransverse ligaments are the short bands connecting the inferior border of the neck of a rib to the anterior surface of the corresponding transverse process of the upper six vertebrae. These ligaments prevent the excessive mobility of the upper six ribs that might occur during deep inspiration1.
The last rib is attached to the costal process of L1 and L2 by the lumbocostal ligament2.
Last update: 11/Nov/2023