What Does This Man Do for a Living?
A 48-year-old man with no significant past medical history presents to the emergency department (ED) with a 3- to 4-month history of slowly progressive difficulty with active, but not passive, extension of the ring and little fingers of his right hand. He denies any tingling, numbness, or skin changes in his hands or his forearms. There is no neck pain, and a thorough neurologic review of symptoms, including motor weakness, decrease in proprioception, and 2-point discrimination, is negative.On physical examination, the patient appears well with normal vital signs. His temperature is 98.6°F (37°C); pulse, 86 bpm; respiratory rate, 18 breaths/min; and blood pressure, 135/85 mm Hg. The patient’s oxygen saturation is 98% while breathing ambient air. The appearance of the patient’s hands is shown in Image 1. The palmar surfaces are noted to be normal, without any skin changes (including rashes or discrete lesions). He has no pain or tenderness in the neck, with a full range of motion. Passive range of motion of the wrist and fingers is normal, with no evidence of increased resistance to movement. Active flexion of the fingers is normal, but all extension of the ring and little fingers of the right hand is absent. The left hand has a normal range of motion, including extension and flexion, of all fingers.
The examining physician (please note, this was not the author) was also able to guess the patient’s occupation. Which anatomic structure is affected, and where is it most vulnerable?