Costovertebral and costotransverse joints
The costovertebral joints describe two groups of synovial plane joints which connect the proximal end of the ribs with their corresponding vertebrae, enclosing the thoracic cage from the posterior side. Precisely, these joints are described as;
- The connection between the heads of the ribs with the sides of one, or two adjacent vertebral bodies are known as the costocorporeal joints/joints of head of ribs.
- The articulations of the necks and tubercles of the ribs with the transverse processes of their corresponding thoracic vertebra are the costotransverse joints.
The movements on these joints are called ‘pump-handle’ or ‘bucket-handle’ movements, and are limited to a small degree of gliding and rotation of the rib head. The function of these movements is to enable lifting of the ribs upwards and outwards during breathing. The end result is the increase of the lateral diameter of the thorax and subsequent expansion of the lung parenchyma as the air is being inhaled.
|Type||Synovial plane joint|
|Articular surfaces||Costocorporeal joint: Costal demifacets on vertebrae T1-T10, full costal facets on vertebrae T1, T11, T12; heads of ribs 1-12
Costotransverse joint: Tubercle of rib, transverse costal facet on transverse process of numerically equivalent vertebra
|Ligaments||Costocorporeal joint: Radiate, intra-articular ligaments (joints 11-12)
Costotransverse joint: Costotransverse, superior costotransverse, lateral costotransverse, accessory ligaments
|Innervation||Lateral branches of the dorsal rami of C8-T11 spinal nerves|
|Blood supply||Supreme intercostal, posterior intercostal arteries 1-10|
|Movements||Costocorporeal joints: internal rotation and elevation of head of rib
Costotransverse joints 1-6: internal rotation of neck of rib
Costotransverse joints 7-10: posteromedial translation of neck of rib
This article will discuss the anatomy and function of the costovertebral joints; costocorporeal and costotransverse.
- Joints of heads of ribs (costocorporeal joints)
- Costotransverse joints
- Blood supply
- Muscles that act on the costovertebral joints
Joints of heads of ribs (costocorporeal joints)
The costocorporeal joints connect the concave costal facets of the thoracic vertebra and the convex articular facets found on the heads of all ribs;
- Vertebrae T1-T10 have two costal facets; a superior one and an inferior one. When these facets are interrupted by the superior or inferior margins of vertebral body, they are often referred to as costal demifacets,.
- The heads of ribs 2-10 articulate with the bodies of two adjacent vertebrae: the superior costal facet of the numerically equivalent vertebra, and the inferior costal facet of the vertebra immediately superior to it (e.g. rib 2 articulates with vertebrae T1 and T2). As doing so, the ribs make contact with the intervertebral disc between the relevant vertebrae.
- Ribs 1, 11 and 12 are accommodated by a single, uninterrupted, costal facet on the respective thoracic vertebra (T1, T11 and T12)
The first, eleventh and twelfth costocorporeal joints are the simple synovial joints. The joints 2-10 are the complex and compound joints, as they contain the intra-articular ligaments which split the synovial cavity into two compartments.
Ligaments and joint capsule
Costocorporeal joints are enclosed by a fibrous capsule and reinforced by capsular, radiate and intra-articular ligaments. The fibrous capsule of each joint extends between the margins of the costal and vertebral articulating surfaces. The posterior sides of fibrous capsules blend with the costotransverse ligaments.
Radiate ligaments span from the anterior surface of each rib heads to the adjacent vertebral bodies and intervertebral disc. They span into three directions;
- Superiorly, to connect the rib with the vertebra immediately above
- Horizontally, to connect the rib head with IV disc
- Inferiorly, to anchor the rib to its respective thoracic vertebra (i.e. rib 2 to vertebra T2)
This applies to the complex costocorporeal joints, i.e. from second to tenth. In the first, eleventh and twelfth ribs, the radiate ligaments connect the respective ribs with their corresponding vertebra and the vertebra above.
Intra-articular ligaments are present in complex costocorporeal joints only (i.e those of ribs 2-10). In each joint, this ligament spans horizontally from the crest on the head of rib to the adjacent intervertebral disc. In this way, the intra-articular ligaments divide the joint cavity to the superior and inferior compartments.
Costotransverse joints are the connections between the articular facet on the tubercle of the rib and the transverse process of its numerically equivalent vertebra. Only the upper ten ribs participate in these joints; instead the eleventh and twelfth ribs pass anterior to, and independent of the transverse process. since the eleventh and twelfth rib don’t have it.
Costotransverse joints are the connections between the articular facet on the tubercle of the rib and the transverse costal facet located on the transverse process of the vertebra at the same numerical level.
The articular surfaces on the tubercles of ribs 1-6 are vertically convex, while the corresponding costal facets on the transverse processes are accordingly concave. In the case of ribs 7-10, the articular facets are nearly flat and oriented inferomedially and posteriorly, facing the superior surfaces of the transverse processes.
Ligaments and joint capsule
Costotransverse joints are enclosed with their respective fibrous capsules that attach to the margins of the articular facets. The inner surface of each capsule is lined with a synovial membrane which bounds the synovial cavity in each joint.
The joints are reinforced by the costotransverse, superior and lateral costotransverse, and accessory ligaments:
- The costotransverse ligament fills the narrow interval between the vertebral transverse process and the rib neck. Its many short horizontally oriented fibers form this connection starting from the back of the rib neck all the way to the anterior surface of the adjacent transverse process.
- The superior costotransverse ligament connects the superior surface of the rib neck to the inferior surface of the transverse process of the vertebra immediately above. It is featured in all costotransverse joints except the first one. The ligament consists of two layers, anterior and posterior, that are separated by the fibers of the external intercostal muscle. The anterior layer takes a superolateral course, while the posterior one runs in the superomedial fashion. On their vertebral attachments, the anterior layer blends with the internal intercostal membrane, while the posterior one fuses with the external intercostal muscle.
- The lateral costotransverse ligament connects the tip of the transverse process with the lateral, non-articular, part of the rib tubercle.
- An accessory ligament sits medial to the superior costotransverse ligament, being separated from it by the posterior ramus of thoracic spinal nerve.
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Both types of costovertebral joints are innervated by the lateral branches of the posterior rami of spinal nerves C8-T11. The innervation has a segmental pattern; each joint receives the fibers from a spinal nerve of its numerically equivalent level and from the level above.
Costovertebral joints are supplied by the branches of thoracic aorta, namely the supreme intercostal and 1st-10th posterior intercostal arteries.
Learn more about these blood vessels here.
The movements of the costocorporeal and costotransverse joints are closely related and usually described together. As the joints are firmly stabilized by their respective ligaments, the range of motion is small and falls down to slight gliding and rotational movements of the vertebral ends of the ribs. However, given that the ribs are relatively long, a small movement on their vertebral end will cause movement of much larger amplitude at their sternal end. The end result of these movements is anterior and lateral expansion of chest during inhalation.
Here is how these movements happen.
- Due to an almost vertical orientation of the costotransverse joints in the upper six ribs, the elevation of ribs will cause the rib necks to glide superiorly. But as the articular surfaces are notably curved, the main movement will be the rotation of the rib heads around their antero-posterior axes.
- The seventh-tenth costotransverse joints are oriented posteromedially, so the movements of ribs during inhalation will cause the posteromedial gliding and rotation of the rib necks.
- All the costocorporeal joints move concurrently with the costotransverse, with slight superior gliding and internal rotation of the rib heads
According to a study by Duprey ey al., the total average ranges of motion (RoM) are found to be as follows; 17° for torsion of the rib , 4.5° for the superoinferior flexion of the rib, and 2.5°-3° for the anteroposterior flexion of the rib. Since the sternal ends of ribs are lower than the vertebral ones, the elevation of ribs 1-6 will move the sternum superiorly and anteriorly. This is referred to as the ‘pump-handle’ movement.
Furthermore, given that the ribs are curved in a way that their middle thirds are lower than their sternal and vertebral ends, the rotation on 7-10 joints will move the rib shafts laterally, expanding the transverse diameter of the thorax. This is called the bucket-handle movement.
Accessory movements that happen on the thoracic spine, needed for unhindered active RoM are the rotation of vertebrae in horizontal plane and gliding of rib necks in antero-posterior direction.
Just like for all the facet joints of thoracic spine, the close packed position for the costovertebral joints is when the vertebral column is fully extended, while the joints are loosely packed midway between flexion and extension. The capsular pattern of the AC joint is equal limitation of lateral flexion and rotation, followed by extension of the vertebral column.
Learn everything about the costovertebral joints with our video tutorial, quiz and labeled atlas images.
Muscles that act on the costovertebral joints
The prime movers of the costovertebral joints are the muscles of respiration.
However, all the muscles that attach to the ribs and which are sorted as accessory respiratory muscles can cause the movements on these joints;
sternocleidomastoid, scalene, serratus anterior, pectoralis major, pectoralis minor, latissimus dorsi and serratus posterior superior.