The colonic component of the splenic flexure occurs lateral to the mesenteric confluence. The flexure spring stiffness is independent of spin rate. The root of the mesentery extends from the duodenojejunal flexure to the ileocaecal junction. Displacement amplification can also be accomplished by using rigid struts connected by flexure bearings. A tilt flexure serves as the tilt-motion isolator. In bulls, rams and boars, the sigmoid flexure of the penis straightens out during erection. This vertical stress is supported by the mantle and the flexure of the lithosphere. The colonic component of the hepatic flexure is draped around this mesenteric confluence. The northeast-southwest upland and watershed follows the axis of an epeirogenic flexure. Early in the fourth week the cephalic part bends sharply forward in a cephalic flexure. The first part of the duodenum ends at the corner, the "superior duodenal flexure". Current methods typically employ strain gaging or similar techniques to monitor board flexure. The "second part", or "descending part", of the duodenum begins at the superior duodenal flexure. It is simplified when each flexure is considered as being centered on a mesenteric contiguity. It is also thought to help digestion by widening the angle of the duodenojejunal flexure.