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.
January 18, 2016. A timing chain is a metal chain, as opposed to the timing belt which is made of rubber. The chain is located inside of the engine and needs to be lubricated by the oil in the engine so everything runs together. Every time you use the engine, the timing chain will be used.