Final answer:
The posterior interosseous nerve is derived from the radial nerve, and the anterior interosseous nerve comes from the median nerve, both originating from the brachial plexus.
Step-by-step explanation:
The posterior interosseous nerve is a branch of the radial nerve and the anterior interosseous is a branch of the median nerve. The radial nerve is a major peripheral nerve of the arm and is part of the brachial plexus. It supplies the muscles on the posterior aspect of the forearm, which are primarily involved in wrist and finger extension. The median nerve also stems from the brachial plexus, and supplies most of the muscles in the anterior compartment of the forearm which are essential for wrist and finger flexion, including the flexor digitorum superficialis and the flexor digitorum profundus.