Which nerve is located in the little finger?

The ulnar nerve is the correct choice as it is primarily responsible for the sensory and motor functions in the little finger, as well as part of the ring finger. It plays a critical role in the innervation of the muscles that control fine motor skills of the hand and also provides sensation to the skin on the palmar and dorsal aspects of the little finger.

In contrast, the median nerve is primarily involved with the thumb, index, middle, and part of the ring finger, providing sensation and motor control to the muscles of the forearm and hand that affect these areas. The radial nerve is associated with the posterior aspect of the arm and forearm, controlling the extensor muscles and providing sensation to a different portion of the hand. The musculocutaneous nerve innervates the muscles of the anterior compartment of the arm and does not serve the hand at all. Thus, the ulnar nerve is specifically the one that controls the little finger's sensation and movement.