trochlear notch

The trochlear notch, also known as the semilunar notch, is a C-shaped indentation located on the upper end of the ulna, one of the two bones in the forearm. This notch is crucial for the formation of the elbow joint, as it articulates with the trochlea of the humerus, the bone of the upper arm. The olecranon process forms the upper border of the trochlear notch and is what we feel as the point of the elbow. The coronoid process forms the lower border and fits into the humerus when the elbow is bent. The ulna is found in all land vertebrates, with the elbow joint evolving in birds and mammals.12