Which term describes small movements in motion units that are independent of voluntary muscle movements?

Which term describes small movements in motion units that are independent of voluntary muscle movements?

• A. Joint play
• B. Accessory joint movements
• C. End play
• D. Form dictates

Answer: (B)

Small motions between the joint surfaces that occur without voluntary muscle action are called accessory joint movements. These arthrokinematic motions—glide, slide, and spin of the articular surfaces—happen regardless of what the muscles are doing and are essential for smooth, full range of motion. They reflect how the joint surfaces interact and are guided by the capsule and ligaments, so assessing them helps gauge joint integrity and mobility beyond what muscle action can produce. This distinguishes them from broader passive joint movements or end-range sensations, which are not specific to the tiny intra-articular motions described here.

Small motions between the joint surfaces that occur without voluntary muscle action are called accessory joint movements. These arthrokinematic motions—glide, slide, and spin of the articular surfaces—happen regardless of what the muscles are doing and are essential for smooth, full range of motion. They reflect how the joint surfaces interact and are guided by the capsule and ligaments, so assessing them helps gauge joint integrity and mobility beyond what muscle action can produce. This distinguishes them from broader passive joint movements or end-range sensations, which are not specific to the tiny intra-articular motions described here.