Variant anatomy and codes of the human brachial plexus

Background. Understanding the complexities of formation and structural features of the brachial plexus remains important for diagnosis, effective surgical treatment and regional anesthesia. 
Aim. To identify variants of the brachial plexus structure and develop a system for their coding. 
Material and methods. Macroscopic anatomical layer-by-layer and macro-microscopic intratubular dissection of 121 brachial plexus preparations were performed in 105 cadavers of men and women aged 40100 years. A database was formed from the obtained indicators in the MS Excel 2012 program, and their processing was carried out using Statistica for Windows 12. All indicators were tested for the normal distribution using the ShapiroWilco criterion. When describing the studied indicators, the median (Me) and interquartile intervals [Q1, Q3] were determined, as well as the significance of intergroup differences according to the MannWhitney test. 
Results. It was established that the farther from the spinal cord, the more variants of the macroscopic and macro-microscopic structure of the brachial plexus elements exist: roots 3, trunks 7, divisions 3, bundles 1216, and a total of 20 variants of the general structure were identified. The roots of spinal nerves C6 (66.1%), C7 (66.4%) and C8 (64.2%) take the greatest part in the formation of brachial plexus bundles, 2 times less often C5 (34.8%) and Th1 (33.3%), very rarely C4 (2.5%) and Th2 (0.8%). Reverse coding of variants of the brachial plexus structure in the direction: bundle division trunk (root) allows to briefly and clearly display the entire morphological diversity of the nervous system of the human upper limb. The results obtained should be taken into account when diagnosing injuries, performing regional anesthesia, reconstructive operations, rehabilitation measures, creating neurosimulators, neurochips, and nerve conductors. 
Conclusion. 20 different variants of the general structure of the human brachial plexus have been identified and a reverse coding system has been developed.