The end of of a muscle that is attached to the immovable bone is called the

origin.

The end of a muscle that is attached to the immovable  bone is called the origin.

In some parts I have found that they refer origin of a muscle as the bone, while in other parts I have found that they refer tha origin is part of the muscle.

Anyway, the question is refering to this part: the origin of a muscle, which is a the end of a muscle that is attached an immovable or less movable bone.