 At the junction of this surface with the front of the body is a rough eminence, the tuberosity of the ulna, which gives insertion to a part of the brachialis; to the lateral border of this tuberosity the oblique cord is attached.Its "lateral surface" presents a narrow, oblong, articular depression, the radial notch.Its "medial surface", by its prominent, free margin, serves for the attachment of part of the ulnar collateral ligament.