Follow the anterior branches from the lateral and medial cord of the brachial plexus that form the letter “M” - musculocutaneous, median and ulnar nerves. Pay particular attention to the course of the nerves at the cubital fossa at the elbow.
Note that after innervating the flexor compartment of the arm the musculocutaneous passes between the biceps and the brachialis to become the lateral cutaneous nerve of the forearm (hence the term musculocutaneous). Note the relationship of the biceps tendon to the brachial artery and the median nerve (“TAN” from lateral to medial). Note the ulnar passes posterior to the medial epicondyle.
Note the radial nerve (from the posterior cord) innervates the posterior compartment of the arm and the forearm. It slips into the arm under cover of the brachioradialis muscle.