SDF and DDF tendons prevent over extension of ______

• A. Carpus and fetlock joint
• B. Stifle
• C. Hock
• D. Interphalangeal joints

Answer: (A)

The main idea here is how the stay apparatus uses the flexor tendons to limit movement in the limb during standing. The superficial and deep digital flexor tendons are arranged so that, when the horse is bearing weight with little muscular effort, they stay taut and pull the limb into a safe, semi-flexed position. This tension helps prevent the fetlock and carpus from extending too far backward, effectively stopping hyperextension at those joints.

In this setup, the SDF and DDF work with ligaments that “check” or restrict excessive extension, so the fetlock and the carpus are held within a functional range. Other joints like the stifle, hock, and the interphalangeal joints rely on different ligaments and structures for stability and are not the primary targets of these two tendons in the stay mechanism.