[Brachial plexus roots in man].

The roots of the brachial plexus have been examined bilaterally on the bodies of 69 men. Three types of plexus were distinguished. In type I, covering 26.1% of the cases, the plexus was formed by the roots C4-Th1. Type II included 73.2% of plexus examined and it was composed by the roots C5-Th1. In type III, represented by 0.7% of the cases, the plexus was made by roots C5-Th2. In between the roots regularly taking part in the formation of the brachial plexus the thinnest was Th1 -in 52.2%, C5-in 47.8%, and the thickest was C7-in 43.5%, C8-in 37.0%, C6-in 18.1%, C5 -in 1.4% of the cases. The internal structure of the brachial plexus roots was characterized by a great individual variability and asymmetry. The roots differed between one another in thickness, number of fascicles, size of their cross-section area and index of the fascicle's area. The studied features underwent big changes during postnatal life, especially up to the 22nd year of life.