Final answer:
The ulnar nerve innervates the palmaris brevis muscle, which is a hypothenar muscle of the hand.
Step-by-step explanation:
The Palmaris Brevis muscle, found in the palm of the hand, is innervated by the superficial branch of the ulnar nerve. This nerve, a continuation of the ulnar nerve as it courses superficially along the hand, is responsible for providing sensory innervation to the skin of the medial part of the palm and the palmaris brevis muscle.
Functionally, the Palmaris Brevis muscle aids in hand movements, particularly in controlling the skin's tension and assisting with grip and grasping motions. While not present in all individuals, this muscle contributes to the intricate movements and functionality of the hand. Its innervation by the superficial branch of the ulnar nerve showcases the complex network of nerves responsible for the precise motor and sensory control required for hand dexterity and function.