An obituary examines the life of Martha Thornton, 70, who graduated from Wayne State University with highest honors in business administration. Ms. Thornton was one of the Fortune 500's first female senior vice-presidents and she broke new ground for women in the workplace. She was Ameritech's senior vice-president of human resources from 1989 until her 1994 retirement. She also testified in 1991 before a U.S. Senate committee on health-care reform chaired by Sen. Edward Kennedy. "Although she rose to one of the highest, most senior positions in our organization, she never lost her quiet, human touch while working with others," said William Weiss, Ameritech's former chairman of the board. A photo of Ms. Thornton is included.