Upper extremity entrapment neuropathies are chronic injuries to peripheral nerves, presumably from sustained pressure on the nerve in question. These conditions are controversial, and physicians disagree, unfortunately too often, about whether a neuropathy is present, what caused the neuropathy, and what the proper impairment rating should be. Carpal tunnel syndrome is the most common entrapment or “pressure neuropathy” and must be differentiated from other causes of nerve dysfunction such as viral illness, toxins (eg, heavy metals), and systemic diseases such as diabetes or vasculitis. Each of the upper extremity nerves has many potential sites of entrapment, which most frequently occurs secondary to a congenital anomaly such as anomalous fibrous band, muscle bellies, or arteries. Ganglion cysts, lipomas, tumors, and fracture callus or nonunion also have been reported as a cause of these rare neuropathies. Diagnosis of entrapment is challenging because entrapments are uncommon to rare, but arm pain is common in individuals who move their arms repetitively at work, avocation, or sport, and establishing causation also is controversial. Severe entrapment essentially is total destruction of the nerve involved, but, in a lifetime of practice, most physicians will not see a nerve entrapment that progresses to complete loss of all motor and sensory function.