Washington Esthetician State Board Practice Exam

What nerve is responsible for supplying the thumb?

1. The ulnar nerve

2. The median nerve

3. The radial nerve

4. The digital nerve

The correct answer is: The radial nerve

The correct answer is the median nerve. This nerve plays a crucial role in the sensation of the thumb and muscles controlling thumb movement. Specifically, it supplies the thenar muscles, which are responsible for the opposition and flexion of the thumb, enabling precise movements that are essential for gripping and pinching actions. The median nerve is also responsible for providing sensation to the skin of the palmar side of the thumb, the index finger, and part of the middle finger, which is why it is integral to thumb function. In contrast, the ulnar nerve primarily supplies the fourth and fifth fingers and is involved more with the fine motor skills of those digits. The radial nerve is responsible mainly for the posterior aspect of the arm and forearm, influencing the wrist extensors and providing sensation to the back of the hand. The digital nerve, while relevant to the sensation in fingers, does not directly control the thumb's muscular movement; it branches off from the median and ulnar nerves, depending on the finger involved. Understanding these anatomical relationships highlights the significance of the median nerve in thumb function.