An ultrasound probe is equipped with a transducer element array and an internally located position marker trackable by a position sensing system or the like. The position marker is supported by a movement and rotation constraining fixture. The fixture is rigidly connected to the transducer element array of the probe. The fixture constrains the position and orientation of the position marker to match a spatial reference relationship with the transducer element array in the position marker's constrained degrees of freedom. The position marker may moved along and rotated in its unconstrained degrees of freedom to match the spatial reference relationship with the transducer element array.