Final answer:
Improper biomechanical motion between two vertebrae is referred to as hyperextension or hyperflexion, occurring when there's excessive motion. The joints between articular processes are called zygapophysial joints, and they allow for movements like flexion and rotation. The joint with an intervertebral disc is an amphiarthrosis.
Step-by-step explanation:
Improper biomechanical motion between two vertebrae is best referred to as hyperextension or hyperflexion. These conditions occur when the movement goes beyond the normal range of motion for the vertebral joint. The joints between the articular processes of adjacent vertebrae, which can contribute to movements such as flexion, extension, lateral flexion, abduction, adduction, and rotation, are called zygapophysial joints or facet joints. These are classified as plane synovial joints and offer only limited motion. When considering the types of joints, the one including an intervertebral disc would be classified as an amphiarthrosis, which means it is a joint with limited mobility.