I'm slowly studying human anatomy. So far I've only "covered" most of the skeletal and muscular structure of the arm. Did this "study" and though some of you might take a look and see if I got it all wrong :
Those two bumps are important bony landmarks in determining the orientation of the elbow joint. In your drawing, you've made it a bit vague, and given all the bulk of the elbow to the ulna instead of the humerus.
You've pulled the scapula (shoulderblade) too far around. It should be half on, and half off the rib cage -- not completely off the ribcage and under the deltoids. In essence, you've made the humerus too short.