Original Editor - Rewan Aloush
Introductionribs with their corresponding thoracic vertebrae, enclosing the thoracic cage from the posterior side.
Joining of ribs to the vertebrae occurs at two places
- Head - Two convex facets from the head attach to two adjacent vertebrae. This forms a synovial planar (gliding) joint, which is strengthened by the ligament of the head and the intercapital ligament.
- Tubercle of the rib - Articulation of the tubercle is to the transverse process of the adjacent vertebrae. This articulation is reinforced by the dorsal costotransverse ligament
Costovertebral joint consists of the head of the rib articulating with the head of a typical rib has two facets (each facet with a separate synovial joint) separated by a ridge:
- Lower rib facet articulates with the upper costal facet of its own vertebra
- Upper facet articulates with the lower facet of the vertebral body above.
- The first rib articulates with the T1 vertebra only and the lowest three ribs articulate only with their own vertebral body.
There are two types of ligaments:
- intra-articular ligament - attaches the intervertebral disc to the ridge in between the two facets of the head of the rib.
- radiate ligament - formed by three bands which connect the rib head to the vertebral bodies. A superior band runs to the vertebral body above and an inferior band runs to the vertebral body below. A central band runs deep to the anterior longitudinal ligament and blends into the intervertebral disc to join the ligament on the opposite side. In the first rib and the last three ribs, only two bands exist as they only articulate with their own vertebra.
There are two facets of a tubercle of a rib, the medial and lateral.
- The hyaline cartilage-lined medial facet forms a plane synovial joint with the tip of the transverse process which is reinforced by a capsule.
- The lateral facet is attached to the transverse process through three ligaments:
- Lateral costotransverse ligament - attaches the lateral facet to the tip of the transverse process of the vertebral body.
- Costotransverse ligament - attaches the back of the neck of the rib to the front of the transverse process
- Superior costotransverse ligaments - attaches the neck of the rib to the underside of the transverse process of the vertebra above
The lower two ribs are only attached by ligaments and do not form synovial joints with the transverse process.
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.
The costovertebral complex is an essential component of the biomechanics of chest wall movement. The costovertebral ligaments make the actions of the costovertebral joints and intervertebral movement possible. The ligaments function to:
- Affix, stabilize and allow some motion of the ribs on the thoracic vertebra at the costovertebral joint. Their presence helps with the load-bearing, protection, posture and scaffolding roles that the thoracic cage provides with their stabilization properties .
- Allow and limit movement of the ribs at the transverse joint to allow for maximum expansion of the thoracic cavity as needed for respiratory demand. Their actions on both the costovertebral and intervertebral complexes allow lateral bending and axial rotation.
Muscles That Act on the Costovertebral Joints
The prime movers of the costovertebral joints are the muscles of respiration.ie
However, all the muscles that attach to the ribs and which are sorted as accessory respiratory muscles can cause the movements on these joints;
Innervation of the Costovertebral Ligaments
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.
Costotransverse disorders are disorders affecting or involving the costotransverse and costovertebral joints and ligaments. Important considerations:
- Often overlooked yet it can be responsible for pain in the thoracic region or functional impairments of the thoracic spine.
- May occur due to trauma, degenerative changes, tumours, deformities or muscular spasm.
- A diagnosis is usually made through a clinical examination with treatment consisting of mobilisation, exercise therapy, injections and/or fixation of unstable joints.
- Gray.H,Gray's anatomy 20th edition,page 299
- Radiopedia Costrovert. Joint Available from:https://radiopaedia.org/articles/costovertebral-joint (last accessed 10.5.2020)
- Kenhub CV joints Available from:https://www.kenhub.com/en/library/anatomy/costovertebral-joints (last accessed 10.5.2020)
- B A Young, H E Gill, R S Wainner, T W Flynn. Thoracic costotransverse joint pain patterns: a study in normal volunteers. BMC Musculoskelet disord. 2008; 9: 140