The trapezius muscle resembles a trapezium (trapezoid in American English), or diamond-shaped quadrilateral. Such a diagram is called a vowel quadrilateral or a vowel trapezium. Later, the trapezium was frequently replaced by an isosceles triangle. The opponens pollicis originates on the tubercle of the trapezium and the flexor retinaculum. The tubercle of trapezium is a tubercle found on the anterior surface of the bone. The badge is a horizontal oval above an inverted trapezium. In 1984, the rectangles were replaced by a yellow trapezium. Problem 52 finds the area of a trapezium with (apparently) equally slanting sides. The parish of Barrington is roughly a trapezium in shape and covers 2282 acres. Additionally, in proposition 15, he establishes the centre of gravity of the trapezium. An example of this is seen with the Trapezium cluster. The Kelly bag is a trapezium closed with two straps. The principle of this procedure is the removal of the trapezium bone. The platforms are in the shape of a trapezium.