Flexure

Systemic and local hygiene has supplanted drugs and surgery in the treatment of diseases of the anus, rectum, sigmoid flexure, and vermiform appendix.

Source: tatoeba (11034139)

but scarce had I drawn back mine arms, strained the outward flexure of my knee-joints, and was fixed in an apt disposure to take the corvetto primo and leap-valiant of the cour, when methought suddenly there came in and did appear before me mine ancient, most reverend and singular good friend, the rector of Saynt Andrew of S—, nearest in neighbourhood, but not of mine own cure, myself being of D— manor house in the same vicinage,—who astonished beyond measure at my so extasied gladness, demanded wherefore I did carry myself on this wise?

Source: wiktionary

varying with the flexures of the valley through which it meandered

Source: wiktionary

The Stomach [of a weasel] about three inches long; proportionably, more than a Dogs. An inch in Diametre at the upper Orifice; and the nether, ¼; having a flexure towards its Conjunction with the Guts: ſhaped like to the body of a pair of Bag-Pipes.

Source: wiktionary