Which combination correctly describes the thoracic limb according to the material?

Which combination correctly describes the thoracic limb according to the material?

• A. Has reciprocal apparatus and bears less weight
• B. Has reciprocal apparatus and bears more weight
• C. Lacks reciprocal apparatus and bears more weight
• D. Lacks reciprocal apparatus and bears less weight

Answer: (C)

The key idea is how the forelimb (thoracic limb) supports the body and how a reciprocal locking mechanism affects that support. In the material’s description, the thoracic limb lacks the reciprocal apparatus that links elbow and carpal joints to create a locking stay. Without this automatic locking, the limb relies more on muscular control to stay extended and to bear load. Since the forelimbs carry the head and trunk and form the primary contact with the ground, they bear a larger share of body weight. The hind limb, by contrast, uses the reciprocal apparatus to help with locking and movement, so its load distribution differs. Therefore, describing the thoracic limb as lacking reciprocal apparatus and bearing more weight aligns with how weight distribution and joint mechanics are presented.

The key idea is how the forelimb (thoracic limb) supports the body and how a reciprocal locking mechanism affects that support. In the material’s description, the thoracic limb lacks the reciprocal apparatus that links elbow and carpal joints to create a locking stay. Without this automatic locking, the limb relies more on muscular control to stay extended and to bear load. Since the forelimbs carry the head and trunk and form the primary contact with the ground, they bear a larger share of body weight. The hind limb, by contrast, uses the reciprocal apparatus to help with locking and movement, so its load distribution differs. Therefore, describing the thoracic limb as lacking reciprocal apparatus and bearing more weight aligns with how weight distribution and joint mechanics are presented.