trapezoid line trapezoid line from the conoid tubercle an oblique ridge, the trapezoid line (or trapezoid ridge, or oblique), runs forward and lateralward, and affords attachment to the trapezoid ligament on inferior surface of clavicle trapezoid lineleft clavicle. inferior surface. (oblique line for trapezoid lig. labeled at center right.)detailsidentifierslatinlinea trapezoideata98a02.4.02.011ta21178fma74586anatomical terms of bone