The trochlear notch is a “C”-shaped articular surface of the proximal ulna. There is a central ridge on the trochlear notch that articulates with the saddle-shaped trochlea of the humerus forming a hinge that makes up the largest part of the elbow joint. The surfaces of both the trochlea and trochlear notch are covered by articular cartilage. This articulating surface is one of the two joints in the elbow.