Descending the cervical spine, the orientation of the facets gradually transition to be more vertical in the frontal plane. At the upper cervical spine, the plane of the facets is perfectly horizontal in the transverse plane. F acet joints determine the type of motion (i.e., the direction of motion) that can occur there.

Facet joints function to guide motion at that segmental joint level of the spine. The scientific name for facet joints is zygapophyseal joints, hence they are also often known as Z joints. Facet joint, formed by the articulation of superior and inferior articular processes from adjacent vertebrae (synovial joint).The intervertebral discs help to absorb shock.The greater the relative height of the discs compared to vertebral body height, the greater the possible motion at that region of the spine. In the cervical spine, they total 40% of its height. Overall, the intervertebral discs comprise 25% of the height of the entire spine. The disc joint’s thickness allows for a great deal of motion.The increasing size of the vertebral bodies and the discs attached to them descending the spine helps the disc joints bear the increasing weight of the portion of the body above it. The disc joint bears the weight of the body above it.As a whole, the disc joint itself has three major functions: Disc Joint, between vertebral bodies – adjacent vertebral bodies are joined by intervertebral discs, made of fibrocartilage ( cartilaginous joint, known as a symphysis).There are two different joints present throughout the vertebral column: The disc joint (determines how much vertebral motion is possible at a particular segmental level), and the facet joints (determine the type of motion) The joints of the cervical spine can be divided into two groups – those that are present throughout the vertebral column, and those unique to the cervical spine. The ALL and the posterior longitudinal ligament (PLL) are confluent with the outer fibers of the annulus.permit diffusion of nutrients from the subchondral bone to the disk and serve as insertion points for the inner fibers of the annulus.serves as the growth plate and is responsible for endochondral ossification.serves as a barrier to nucleus pulposus pressure on the vertebral body to limit protrusion.The cartilaginous endplate is composed of hyaline cartilage and is located adjacent to the subchondral bone. Posterolateral disk herniations are fewer in frequency, likely secondary to the posterolateral location of the uncinate process.Movement in the coronal plane is limited by the uncinate process however, the disks allow for some anteroposterior translation.Anteriorly, the disks are thicker than posteriorly to facilitate the lordotic curvature of the cervical spine.In the coronal plane, the superior surface of the disk is concave and the inferior surface is convex to conform to the adjacent vertebral bodies.IVD height grows more slowly than does vertebral body height (one third of the length of the spine is related to the disks at birth, one fifth of total spinal length after the age of 7 years).

Move up and down in essential anatomy 3