Which two tendons are the primary components of the stay mechanism?

Which two tendons are the primary components of the stay mechanism?

• A. Biceps brachii tendon and triceps tendon
• B. Common digital extensor tendon and ulnaris
• C. Flexor carpi ulnaris tendon and flexor digitorum profundus tendon
• D. Superficial digital flexor tendon and deep digital flexor tendon

Answer: (D)

The stay mechanism works by using passive tension in the tendons to keep the limb extended while the animal is standing, so muscular effort isn’t needed to hold it up. The two tendons that form the core of this system are the superficial digital flexor tendon and the deep digital flexor tendon. As the horse bears weight, these flexor tendons run along the back of the limb and, through their connections with surrounding ligaments, create a locking arrangement at the fetlock, pastern, and coffin joints. This tension effectively supports the leg in extension, letting the horse stand for long periods with minimal muscle activity. Other tendons are involved in moving or stabilizing the limb, but they don’t provide the primary standing lock in the stay mechanism.

The stay mechanism works by using passive tension in the tendons to keep the limb extended while the animal is standing, so muscular effort isn’t needed to hold it up. The two tendons that form the core of this system are the superficial digital flexor tendon and the deep digital flexor tendon. As the horse bears weight, these flexor tendons run along the back of the limb and, through their connections with surrounding ligaments, create a locking arrangement at the fetlock, pastern, and coffin joints. This tension effectively supports the leg in extension, letting the horse stand for long periods with minimal muscle activity. Other tendons are involved in moving or stabilizing the limb, but they don’t provide the primary standing lock in the stay mechanism.