Which deformity is characterized by the thumb being pulled backward into alignment with the other fingers?

The deformity characterized by the thumb being pulled backward into alignment with the other fingers is known as the ape hand deformity. This condition results from an injury or dysfunction of the median nerve, which leads to a loss of opposition of the thumb. In this situation, the thumb becomes aligned with the fingers rather than being able to oppose them, mimicking the hand structure of an ape, from which the name derives.

Ape hand significantly impacts the individual's ability to grasp and manipulate objects, making daily activities challenging. This highlights the importance of the median nerve in the coordination and functionality of grasping movements.

Understanding this condition in the context of its anatomical and neurological basis helps clarify why it is categorized uniquely compared to the other deformities mentioned.