Intervertebral joints connect vertebrae together. Depending on their location, they give the spine various degrees of mobility while stabilizing the vertebrae. Facet syndrome is a painful condition of the intervertebral joints that is related to osteoarthritis.
What is the intervertebral joint?
Joints provide a movable connection between two or more bones. The human body has more than 140 joints. Bone joints fall into one of several types of joints depending on their location and the functional requirements thus placed on them. The intervertebral joint, facet joint or vertebral joint is the term used to describe the paired joint connection between articular processes of adjacent vertebrae. Vertebral arch joint and small vertebral joint are considered synonymous terms. Like any joint, the vertebral joint provides mobility. In the case of the intervertebral joint, it involves the mobility of the spine. The joints are sometimes referred to as gliding joints. Unlike other types of joints, the gliding joint does not have a key-in-lock anatomy. Thus, the joints are not constructed according to the form-in-counterform principle and accordingly do not interlock, but consist of relatively smooth articular surfaces. These articular surfaces form a functional unit with the intervertebral discs and the ligaments, which permits sliding movements to a small extent.
Anatomy and structure
Intervertebral joints are planar joints with flat articular surfaces and relatively wide joint capsule, which belong to the so-called diarthroses. The cartilaginous surfaces of the processus articulares superiores of each vertebra meet in the intervertebral joint with the processus articulares inferiores of the respective higher-lying vertebra. The respective position of the joint surfaces involved differs in the individual sections of the spinal column, resulting in a different degree of mobility of the intervertebral joints. The vertebral joints are each located on the processes of adjacent vertebrae of the lumbar and cervical spine. In the cervical spine, the articular surfaces are approximately in the transverse plane at zero position, with the processus articulares superiores of the joint pointing in the dorsal-cranial direction. Within the thoracic spine, the articular surfaces of the vertebral joints also stand in a dorsal-cranial direction, with an additional lateral inclination. The lumbar spine again carries the articular surfaces in the sagittal plane. In addition to the intervertebral discs and ligaments, meniscoid synovial folds also contribute to the functional totality of the intervertebral joint. They project crescent-like into the joint space and are composed of vascular loose or tight connective tissue derived from the joint capsule and encased in an intima.
Function and tasks
Intervertebral joints join the vertebrae of the lumbar, thoracic, and cervical spine in an articulated manner, giving the structures a degree of motion. Without the vertebral joints, for example, a person would not be able to bend down to something or turn to the side. Particularly in the cervical spine, mobility is required by the vertebral arch joints, since otherwise the head could not be turned. From an evolutionary biological point of view, the rotation of the head is not insignificantly involved in survival. Humans perceive sounds that alert them to danger and direct their eyes relatively automatically in the direction of the sound. This gives them a full picture of situations in a very short time. Without the vertebral joints, fixation and the rapid change of fixation points would always be tied to the current field of vision. In their entirety, the intervertebral joints give the different sections of the spine three degrees of freedom, which are ideally aligned with the functional requirements of the individual spinal sections. Flexion and extension, for example, are possible in the sagittal plane, thus allowing forward and backward flexion of the spine. Lateral flexion corresponds to a lateral inclination, which is possible in the frontal plane. The spinal column also only obtains the ability to rotate through its intervertebral joints. In the area of the cervical spine, the joints enable a pronounced rotational movement due to their special anatomy, which makes the cervical spine the most mobile section of the spine due to the requirements described above.The rotational possibilities in the lumbar spine are less than in the cervical spine due to lower demands. The meniscoid synovial folds each compensate for the incongruence of the articulating joint surfaces during movement. In addition to mobility, intervertebral joints also guarantee stability and ensure that the spine does not twist.
Diseases
In addition to the herniated disc, the so-called facet syndrome is sometimes the best-known functional impairment of the intervertebral joints. In a healthy back, vertebrae, joints, ligaments and intervertebral discs cooperate ideally with each other. This gives the back elasticity, stability and functional resilience. In old age, however, the spine often shows signs of wear and tear. Lack of exercise, obesity and genetic disposition are risk factors for increased wear or even arthrosis of the facet joints, which can occur as early as the mid-30s. The intervertebral discs lose water content with age, lose height and stiffen. The reduced elasticity of these structures affects the vertebrae, which slowly lose their distance from each other. In addition, when the ligaments wear out, the spine loses its stability. As a result, the facet joints are subjected to increasing stress, which can cause effusions and inflammatory reactions. The facet syndrome basically corresponds to a load-induced arthrosis of the intervertebral joints, which is accompanied by severe back and neck pain. Since the facet joints have an extraordinarily large number of nerves, deep-lying radiating back pain occurs in particular, which increases with the load. In the morning, patients usually feel stiff, especially in the lumbar spine, and suffer pain throughout the day that increases when they lean back. In addition to muscle tension, facet syndrome can also cause diffuse pain of the buttocks or legs. Depending on the segments of the back that have been damaged by the inflammatory reactions, numbness or other sensations of discomfort and even motor deficits may occur over time.
