1. A COLLAPSIBLE NEUROLOGICAL HAMMER COMPRISING AN EXTENSIBLE HANDLE HAVING OUTER AND INNER ELONGATED TELESCOPING MEMBERS RELATIVELY LENGTHWISE SLIDABLE BETWEEN AN EXTENDED USE POSITION AND A RETRACTED STORAGE POSITION, INTERLOCKING MEANS ENGAGING SAID TELESCOPING MEMBERS TO REGULATE RELATIVE LENGTHWISE SLIDING MOVEMENT OF SAID MEMBERS BETWEEN SAID USE POSITION AND SAID STORAGE POSITION, SAID INNER MEMBER HAVING A FREE END COMPRISED OF ENDWISE EXTENDING SIDEWALL PORTIONS DEFINING A SOCKET THAT IS OPEN ENDWISE AND THAT HAS OPPOSITELY DIRECTED SIDE FACE OPENINGS, ONE LKONG AND ONE SHORT, A HAMMER HEAD HAVING OPPOSITELY DIRECTED LARGE AND SMALL ENDS EACH EQUIPPED WITH A RESILIENT IMPACT ELEMENT, SAID SMALL END BEING MOVABLE THROUGH SAID LONG OPENING TO NEST WITHIN SAID SOCKET AND SAID LARGE END PRESENTING PERIPHERAL SHOULDER STRUCTURE AS LARGE AS THE END OF SAID OUTER MEMBER, AND PIVOT MEANS ENGAGED IN SAID SIDEWALL PORTIONS AND MOUNTING A CENTRAL REGION OF SAID HAMMER HEAD TO ROTATE ABOUT A TRANSVERSE AXIS THROUGH SAID SIDEWALL PORTIONS TO PERMIT SAID HAMMER HEAD TO BE ROTATED BETWEEN AN AXIAL STORAGE POSITION WHEREIN SAID SMALL END IS NESTED WITHIN SAID SOCKET AND SAID LARGE END PROJECTS ENDWISE FROM SAID SOCKET AND PRESENTS SAID PERIPHERAL SHOULDER STRUCTURE FOR ENGAGEMENT WITH SAID OUTER MEMBER TO LIMIT RETRACTION OF SAID INNER MEMBER INTO SAID OUTER MEMBER, AND A TRANSVERSE USE POSITION WHEREIN SAID LARGE END IS ADJACENT TO SAID SHORT OPENING AND SAID SMALL END PROJECTS THROUGH SAID LONG OPENING.