The evaluation of the muscular branching patterns of the ulnar nerve on forearm in the fetuses

Recognition of relationship between the anatomy of ulnar nerve (UN) in fetal period and its course, branching features and variations in adults may contribute to better understanding of anatomical features of NU in forearm. We aimed to present our findings on muscular branching features of NU and detailed morphometric measurements of these branches in a systematic method in fetuses. This study was performed on 52 forearms of 10% formaline-fixed fetuses ranging from between 19 and 37 weeks of gestational age. Branches arising from UN; number and row of arising from main trunk were noted, and type of branching as classified according to muscles they reach. Various morphometric measurements of UN and each of its branches were made. We found that total of 2-6 muscular branches arise from UN to innervate related muscles. UN was classified into 5 main types according to number of branches, and these types were divided into 16 subtypes according to their distribution to related muscles. The arising from UN was named as two branches Type I (n=6); three branches Type II (n=18); four branches Type III (n=24); five branches Type IV (n=3); six branches Type V (n=1). We think that knowledge of demonstration different branching patterns of UN in forearm may help surgeons to prevent complications that may occur during selection and transfer of relevant branch in case of possible nerve damage. Keywords: Fetus, muscular branches, ulnar nerve