Typically, the accessory renal artery courses into the renal hilum to perfuse the upper or lower renal poles. They may also enter the renal parenchyma directly from the renal cortex (called a polar artery). Rarely, they may arise from the lower thoracic aorta, as well as from the lumbar and mesenteric arteries.
The chain rule can be used to find whether they are getting closer or further apart. For example, one can consider the kinematics problem where one vehicle is heading west toward an intersection at 80 miles per hour while another is heading north away from the intersection at 60 miles per hour.
A chain gang is a group of convicted criminals on a labor detail, usually outside of their place of incarceration. Chain gangs were mainly used in the American South in the late 19th and early 20th centuries. To prevent individual prisoners from escaping, the entire group was chained together by manacles around their ankles, wrists or necks. Chain gangs in America were mostly eliminated by the 1950s. Several sources link chain gangs with slavery practices of the South before the Civil War. Inmate labor has been in use throughout history. The chain gang, however, is most often associated with the American South.