Washington Esthetician State Board Practice Exam

Which nerve primarily supplies the muscles in the upper arm?

1. The radial nerve

2. The median nerve

3. The ulnar nerve

4. The cervical nerve

The correct answer is: The radial nerve

The radial nerve is primarily responsible for supplying the muscles in the upper arm. It innervates the muscles that extend the elbow and the muscles in the posterior compartment of the arm and forearm, such as the triceps brachii and the anconeus. These muscle groups are crucial for actions such as pushing and gripping, which are essential for upper body movement. The other nerves listed each have specific functions and muscle groups they innervate. The median nerve is mainly involved in the innervation of the forearm flexors and some intrinsic hand muscles, while the ulnar nerve mainly supplies the intrinsic muscles of the hand. The cervical nerve roots are involved in various functions but do not specifically target the muscles of the upper arm. Understanding the role of these nerves helps in recognizing the complexities of muscle innervation in the upper limb.