Final answer:
The bony landmark between the medial and lateral humeral epicondyles is the trochlea, a spindle-shaped region that articulates with the ulna as part of the elbow joint.
Step-by-step explanation:
The hourglass-shaped bony landmark that lies between the medial and lateral humeral epicondyles is the trochlea. The trochlea is a spindle- or pulley-shaped region on the medial side of the distal end of the humerus which articulates with the ulna bone of the forearm as part of the elbow joint. On the other hand, the capitulum, which is a knob-like structure on the anterior surface of the distal humerus, articulates with the radius bone of the forearm.