This anatomic study of the commonly described inside-out Tuohy needle technique was performed to better define the course of needle passage relative to the anatomic structures in this region including the dorsal sensory branch of the ulnar nerve (DBUN) and extensor carpi ulnaris (ECU) tendon. Ten fresh-frozen cadaver specimens had arthroscopic-guided passage of a Tuohy needle through the triangular fibrocartilage (TFC). Dissection of the ulnar side of the wrist was performed and various measurements were recorded. The average minimum distance between suture A (the suture closest to the nerve) and the DBUN was 1.9 mm. The average minimum distance between suture B and the DBUN was 2.7 mm. The distance between the 2 sutures at the level of the capsule averaged 6.2 mm. The distance between the DBUN and the ECU averaged 7.2 mm. In 5 of 10 specimens the sutures exited on opposite sides of the DBUN. The DBUN is variable in its course but in every case it passes in close proximity to the sutures that exit the ulnar side of the wrist in arthroscopic repair of ulnar-sided TFC tears.