The loins (or: lumbus ) are the sides between the lower ribs and pelvis , and the lower part of the back . ^{[1] [2] [3]} It is often used when describing the anatomy of humans and quadrupeds (such as horses , ^{[4] [5]} pigs ^{[6] [7]} or cattle ^[8] ). The anatomical reference also carries over into the description of cuts of meat from some such animals, e.g. tenderloin or sirloin steak . ^[2]