How does the lacertus fibrosus contribute to maintaining the carpus in extension during standing?

How does the lacertus fibrosus contribute to maintaining the carpus in extension during standing?

• A. It transmits tension from the biceps brachii tendon to the extensor carpi radialis, aiding carpal extension and limb stability
• B. It extends the carpus
• C. It fixes the carpus in flexion
• D. It stabilizes the tarsus

Answer: (A)

The lacertus fibrosus acts as a tension-transmitting band that connects the tendon of the biceps brachii to the extensor carpi radialis tendon. When the limb bears weight, tension generated by the biceps tendon is conveyed through this fibrous band to the extensor carpi radialis, pulling the carpus into extension and helping to stabilize the limb. This mechanism allows the carpus to stay extended with less active muscular effort, which is crucial for standing. It doesn’t directly extend the carpus by itself, and it doesn’t fix the carpus in flexion or stabilize the tarsus.

The lacertus fibrosus acts as a tension-transmitting band that connects the tendon of the biceps brachii to the extensor carpi radialis tendon. When the limb bears weight, tension generated by the biceps tendon is conveyed through this fibrous band to the extensor carpi radialis, pulling the carpus into extension and helping to stabilize the limb. This mechanism allows the carpus to stay extended with less active muscular effort, which is crucial for standing. It doesn’t directly extend the carpus by itself, and it doesn’t fix the carpus in flexion or stabilize the tarsus.