What sensation is lost with an ulnar nerve injury?

The correct answer focuses on the function of the ulnar nerve, which primarily innervates the ulnar side of the hand, specifically affecting sensations in the little finger and part of the ring finger. An ulnar nerve injury results in the loss of sensation in the distal ulnar aspect of the little finger because the nerve provides sensory fibers to this area. The ulnar nerve also contributes to sensation in the palmar aspect of the little finger and the adjacent half of the ring finger, which aligns with the correct choice.

In contrast, the sensations listed in the other options pertain to areas served by different nerves. The distal radial aspect of the index finger is primarily innervated by the radial nerve, while the palmar aspect of the thumb is largely the responsibility of the median nerve. The dorsal aspect of the hand encompasses multiple sensory territories, primarily innervated by the radial and median nerves, and thus is not affected directly by an ulnar nerve injury. Therefore, the loss of sensation in the area innervated by the ulnar nerve is specifically reflected in the choice regarding the distal ulnar aspect of the little finger.