When does the ulnar nerve branch in the wrist?

The ulnar nerve branches in the wrist after passing through Guyon's canal. This anatomical fact is crucial for understanding the potential sites of nerve entrapment or injury. Guyon's canal, located between the pisiform and hook of the hamate bones, serves as a pathway for the ulnar nerve and the ulnar artery to enter the hand. After passing through this canal, the ulnar nerve gives rise to its terminal branches, which innervate the intrinsic muscles of the hand and provide sensation to the skin of the medial aspect of the hand.

Before reaching Guyon's canal, the ulnar nerve is more proximal and has yet to branch into its specific segments that innervate the hand. The notion that the branching occurs at the base of the palm or during elbow flexion is inaccurate; the nerve does not branch at those locations in relation to the wrist. Understanding the precise location where the ulnar nerve branches is important for clinicians when diagnosing and managing ulnar nerve injuries or conditions like ulnar tunnel syndrome.