Joints: In the spine, RA usually affects the cervical spine. The joints in the upper cervical spine include the odontoid process, a tooth-like structure that rises from the body of the axis (second cervical vertebra). The odontoid moved anteriorly (front) with the atlas (first cervical vertebra). The joint space between the axis and the atlas is termed atlantoaxial. The cervical spine includes the lateral (side) joints termed zygapophyseal or facet joints.

Motor: Response to a stimulus (such as a nerve signal) to a muscle, causing it to contract.

Myelogram: A diagnostic test to identify spinal cord lesions. The subarachnoid space of the spinal cord is injected with a contrast medium (a dye), followed by x-rays, CT, or MRI scans. A myelogram can help the doctor see areas of nerve compression around the spinal canal and cord.

Myelopathy: Disturbance of the spinal cord.

Osteophyte: A bony overgrowth; also called a bone spur.

Paresthesias: An abnormal sensation such as tingling, burning, or pins and needles.

Paraparesis: A slight to moderate degree of paralysis in the lower extremities.

Sensory: Relating to sensation: feeling, pressure, temperature.

Subluxation: An incomplete dislocation, or altered contact between joint surfaces.

Vertebral End Plates: The upper and lower plates of the vertebral body adjacent to the intervertebral disc.