Sonoanatomy of the deep branch of the ulnar nerve

Abstract

Introduction This study evaluated the sonoanatomy of the deep motor branch of the ulnar nerve (DBUN) using high-resolution ultrasonography (HRUS). Methods In 60 wrists of 30 healthy adults, the gross course, cross-sectional area (CSA), and diameter of the DBUN were observed by HRUS (frequency band 3-16 MHz). Its course was assessed by using the distance from anatomical landmarks and depth from the skin. Results The DBUN was found in all subjects with HRUS, and it branched off from the ulnar nerve before reaching the hamate bone. At the hook-of-hamate level, the mean DBUN CSA was 1.5 +/- 0.2 mm(2), and the mean diameter was 1.5 +/- 0.2 mm. The mean distance from the hamate hook to the DBUN was 5.4 +/- 1.0 mm, and the mean depth from the skin was 8.6 +/- 1.6 mm. Discussion Sonoanatomy of the DBUN obtained from HRUS may be useful in detecting or preventing DBUN lesions.