An electrode assembly includes a needle and a conductive thread electrode carried in a slot on the surface of the needle. The needle pushes the thread electrode into the body and leaves it in place when the needle is removed. The needle is secured in a housing in a retracted position and moved to an extended position by a latch. In the extended position, one end of the needle remains in the housing and the other end extends from the housing. The needle is attached to a spring inside the housing and is moved by the latch against the urging of the spring to the extended position and locked in place. A protective cover is applied over the needle while extended and removed to insert the needle into the body of a patient.
