 his saying the second one to the back is the one that is specifically called the sacral muscle. this one was specifically called that because it is the one that appears first to the dissectors.
قوله فالثانية إلى خلف هي المخصوصة بأن تسمى عضل الصلب، إنما خصت هذه بذلك لأنها هي التي تظهر أو لا للمشرحين.