Why ulnar nerve is called musician nerve?

The median nerve is also called the musician's nerve. Either can become compressed because of the repetition while playing.

The ulnar nerve compression (aka cubital nerve compression) affects the pinky and part of the fourth finger. Those who play a lot of guitar can have this problem.

The median nerve compression is also called carpal tunnel syndrome. The median nerve affects the thumb, the second and part of the forth. Damage prevents a person from grasping with the thumb. This is called: "the Ape Hand" as apes can not oppose their thumbs. The musician will not be able grasp their instruments.