Above is a quick 5 mins video, where I discussed basic anatomy of the human forearm and hand, so as to analyze what kind of effects will a sword cut injury have on a person.
To summarize the main points discussed in the video:
Found on the anterior part of the forearm, the Flexor Muscles are responsible for wrist flexion and finger flexion (closing your fingers).
Found on the posterior part of the forearm, the Extensor Muscles are responsible for wrist extension and finger extension (straightening your fingers).
Effects of Injury
Damage to these muscles will result in reduction of your ability to perform its respective functions. Injury to the Flexor Muscles will reduce your ability to flex your wrists and fingers. Likewise, injury to the Extensor Muscles will reduce your ability to extend your wrists and fingers.
Holding A Sword or Weapon
To maintain a straight grip with a straight wrist, it will require BOTH Flexor and Extensor Muscles to work. Damage to either one will reduce your ability to maintain a straight wrist, and thus reduce your ability to wield a sword or weapon properly.
The tendons found on the back on your hand is a place that's commonly targeted and hit. Damage to the Extensor Tendons will reduce your ability to straighten your wrists.
Hope this video has helped you to understand the consequences of forearm and hand injuries better.
Ancient Chinese Martial Arts Manuals