Ulnar Claw Hand (Claw Hand): this is due to a lesion with the ulnar nerve. The MCP joints are hyperextended for that ring and small fingers mainly because of the loss of the 3rd and fourth lumbrical muscles on account of a lesion with the deep department with the ulnar nerve. https://www.theorthopaedicandpainpractice.com/what-are-the-different-bones-found-in-my-hand/