Certified Nurses Operating Room (CNOR) Practice Exam

Which nerve is primarily affected when a patient is in a supine position?

1. Femoral nerve

2. Radial nerve

3. Ulnar nerve

4. Brachial nerve

The correct answer is: Brachial nerve

In a supine position, the brachial nerve plexus is primarily at risk due to the stress placed on the shoulder area. When patients are positioned supine, particularly for extended periods or if the arms are positioned improperly, there is a potential for excessive stretching or compression of the nerves that branch from the brachial plexus, which can lead to neuropathies. Maintaining proper arm positioning is crucial in surgical settings to prevent complications such as nerve damage. The brachial plexus, which innervates the upper limbs, can be compromised if arms are abducted excessively or left unsupported. This increases the risk of shoulder and upper limb dysfunction following surgery. The other nerves listed—femoral, radial, and ulnar—are technically associated with different regions and functions of the body. During supine positioning specifically, they are less susceptible to injury caused by posture-related strain compared to the brachial plexus. The femoral nerve affects the lower extremities, and radial and ulnar nerves are lower arms nerves, which are not primarily influenced by the posture of being supine. Therefore, the risk of injury to the brachial nerve plexus makes it the most relevant nerve to consider in this scenario.