Musculus extensor pollicis brevis

The video tutorial explains the Musculus Extensor Pollicis Brevis, a muscle located in the forearm responsible for extending the thumb. It details the muscle's origin, insertion, and innervation by the radial nerve. The tutorial also covers the anatomical features of the hand, including the tabatiere, and describes the muscle's role in thumb movement, specifically in the carpo-metacarpal and metacarpophalangeal joints.

Which nerve innovates the musculus extensor pollicis brevis?

What is the significance of the triangular depression on the radial side of the hand?