From the Research
The ulnar nerve supplies sensation to the hypothenar eminence. This nerve originates from the C8-T1 nerve roots of the brachial plexus and travels down the medial aspect of the arm. As it passes through the Guyon's canal at the wrist, the ulnar nerve divides into superficial and deep branches. The superficial branch provides sensory innervation to the hypothenar eminence, which is the fleshy prominence on the medial side of the palm at the base of the little finger.
Key Points
- The ulnar nerve is responsible for the motor function of the hypothenar muscles (abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi), which form this eminence 1.
- Understanding this innervation is clinically important when evaluating hand injuries, ulnar nerve entrapment syndromes, or when performing regional anesthesia procedures in the hand.
- The anatomy and function of the hypothenar muscles are complex, with variation in motor nerve distribution making surgery of the ulnar side of the palm more challenging 1.
- The pattern of muscle involvement in ulnar neuropathy at the elbow has been studied, with the first dorsal interosseous and abductor digiti minimi muscles being most commonly affected 2.
Clinical Implications
- Clinicians should be aware of the ulnar nerve's role in supplying sensation to the hypothenar eminence when evaluating patients with hand injuries or ulnar nerve entrapment syndromes.
- Knowledge of the anatomy and function of the hypothenar muscles is essential for surgeons performing procedures on the ulnar side of the palm.
- Electromyography (EMG) and nerve conduction studies (NCS) can be useful in diagnosing ulnar neuropathy at the elbow, but may have limited added value if NCS are normal 3.