Usage patterns
〈物〉に肘をつくto rest one's elbow(s) on something
I listened with my elbows resting on the table.
肘で〈人〉を突くto nudge/jab someone with one's elbow
He gave me a discreet nudge with his elbow.
肘を曲げるto bend one's elbow
I bent my elbow to carry the heavy load.
Expressions
肘張るstick out one's elbows · be obstinate; be haughty