College of Massage Therapists of British Columbia (CMTBC) Practice Exam

During a neurological assessment of the upper limb, the therapist compresses patients' right upper arm into shoulder depression. Which upper limb nerve is being tested when the therapist further moves the arm into abduction, extends the elbow, pronates the forearm and flexes both wrists and fingers?

1. Right ulnar

2. Right radial

3. Right medial

4. Left musculocutaneous

The correct answer is: Right radial

The nerve being tested in this scenario is the right radial nerve. The process described involves shoulder depression, abduction of the arm, extension of the elbow, pronation of the forearm, and flexion of the wrists and fingers. The radial nerve is primarily responsible for the motor function of the posterior arm and forearm muscles, which include those involved in extending the elbow and wrist. When the therapist compresses the upper arm and performs the movements indicated, they are specifically engaging the muscles innervated by the radial nerve, particularly those that facilitate extension at the elbow and wrist. The other options do not align with the movements being tested. The ulnar nerve primarily controls flexion of the wrist and fingers, particularly the little finger and the ring finger. The median nerve is mainly responsible for the function of the anterior forearm muscles and parts of the hand, affecting wrist flexion and finger movements but not specifically the actions described. The musculocutaneous nerve generally innervates the flexor muscles of the arm but does not have a substantial role in promoting the described movements of the lower arm and hand. Therefore, the movements outlined in the question point directly to the role of the radial nerve, confirming it as the correct choice