A device for locating a structure (15) inside a body (10) includes a hollow needle (20), a liquid-filled reservoir (31) which is sealingly closed off at one end by means of a displaceable piston (32) and at the other end is in communication with the hollow needle； a sensor (40) for providing a pressure-measurement signal which is representative of the pressure prevailing in the liquid； a converter (50) for converting the pressure-measurement signal provided by the sensor into a converted signal suitable for further processing； and a display device (90) designed to emit at least one visual display signal which is a function of the converted signal. The device further includes a frame (200, 300) which can be worn on the head by a user and can be fixed on the head of the user, the visual display signal being in each case displayed in the range of vision of the user who is wearing the unit on his or her head in every position of the head of the user.
