I'm an anatomy teacher assistance @ my med school....biggest thing to remember about the plexus is.... the main parts of it makes out an "M"... as you're looking from the top of the plexus (with the cadaver flat on it's back), you'll get the "lateral" cord as the 1st leg of the "M", then the bottom of the plexus will be the medial cord, or last leg of the M. Now, what about the "v" in the middle of the M? the lateral cord gives a lateral contribution to one side, and the medial cord gives a medial contribution to the middle. both contributions makes the "v" in the middle of the M. then, those contributions will give off one long main middle cord, called the median nerve. so, to recap....the lateral side of the M= the lateral cord, which supplies the Musculocutaneous Nerve (to the biceps, brachialis, costobrachialis), the middle part of the M contributions = the Median Nerve ( to the thumb/thenar muscles, sensory, thru the flexor compartment, injured in carpal tunnel, etc), then the medial side of the M (or last leg of the M) = the Ulnar nerve (pinky finger muscles like Extensor/Flexor Carpi Ulnaris, sensory to last finger and 1/2, wraps around the medial epicondyle of the humorus or elbow area). Now, all you need to do is review the cranial nerve contributions from the trunks out. The later cord of the M gets (a lil from C4) mainly c5 and c6....the medial cord (bottom leg of M) gets c8 and T1....then, the middle part of the M (the posterior cord is behind this) gets c7 straight into it.
hopefully, my description was "visual" enough for you to make out the M, lol. just ck it against Netters or whatever atlas pic you have of the plexus. let me know what you think...and good luck!!
