It seems that when muscle is discussed it not consistant. Feeder calves are graded on over all wifth width and depth and width of the rear quarter, muscle as defined for eating purposes is ribeye. While the two can go hand in hand, visually it's the rear that gets the attention. Ultrasound or hanging them on the rail is the only way to truly evaluate ribeye. We've all seen animals with tremendous butts and dinky ribeyes and by the same oken, dinky butts and large ribeyes.