A 52-year-old male carpenter from Delhi presents with a 3-month history of progressive weakness and wasting of the intrinsic muscles of his right hand. He reports pain and paresthesias along the medial border of his hand and the medial one-and-a-half fingers. On examination, he has a claw hand deformity affecting the 4th and 5th digits, with weakness of finger abduction and adduction. Sensation is diminished over the hypothenar eminence. There is no sensory loss over the dorsal aspect of the hand. What is the most likely site of ulnar nerve compression?