From which nerve roots does the ulnar nerve originate?

The ulnar nerve originates from the lower trunk of the brachial plexus, specifically from the nerve roots C8 and T1. This is significant because the ulnar nerve is primarily responsible for sensory and motor functions in the hand, particularly for the fourth and fifth fingers. Understanding the specific nerve roots involved is essential for diagnosing and treating conditions related to ulnar nerve dysfunction, such as cubital tunnel syndrome.

The involvement of C7 is not a part of the ulnar nerve's origin, which is why options that include C7 as a root (like C7-C8 or C7-T1) are incorrect. Rather, C7 contributes to the radial and median nerves. The correct identification of the nerve roots (C8 and T1) highlights the specific regions of the spinal cord involved in the formation of the ulnar nerve, emphasizing the clinical importance of these roots in neurophysiologic studies and intraoperative monitoring.