title: Aberrant formation and clinical picture of brachial plexus from the point of view of a neurosurgeon.
abstract: Variations detected during surgery stimulated us to study the variations of the formation of the brachial plexus.
  
  
  METHODS
  We examined 110 brachial plexus in 55 adult cadavers in order to determine the incidence of neural variations. We observed the contribution of the C4 root and possibly Th2 root as well as various anomalies in the origination of each plexiform root and its branches from the spinal cord, and variations of the formation of the neural trunks, fascicles and peripheral branches. We examined their course, anastomosis, thickness and possible absence. We observed the plexiform but not the spinal roots. We saw the pretruncal part of plexus including segment of spinal nerve in the sulcus spinal nerve and anterior branch of the spinal nerve. Motor innervation anomalies in relation to diagnostics are emphasized as well, apart from the anatomic variability. Attention focused on the mechanism and the morphologic reasons for particular types of injuries.
  
  
  RESULTS
  The prefixed type was present in 26 cases (47.3%), and was postfixed in one case. We did not observe any anomaly in the formation of the plexus in 9 cases. We observed 143 anomalies in 46 cases (83.6%). There was one anomaly present in 11 cases and in 35 two or more anomalies were noted. The anomalies were present more frequently on the left side--in 60 cases (41.2%) and bilaterally in 48 cases (33.6%). The anomalies were usually anatomic and in the area of the formation of the terminal branches. The least number of anomalies was present in the area of neural roots.
  
  
  CONCLUSIONS
  This study allowed us to find out and describe unusual and previously not described anatomic variations in the formation of neural roots, trunks, fascicles and terminal branches of the brachial plexus. The formation of the axillary nerve as a continuation of the posterior branch of the superior trunk was noted. (Tab. 4, Fig. 8, Ref. 10.).
authors.affiliation: Department of Neurosurgery, Medical Faculty, Comenius University, University Hospital, Bratislava, Slovakia. bll@fmed.uniba.sk
authors.forename: V
authors.initials: V
authors.lastname: Matejcik
mesh_terms: D001917:Brachial Plexus / Q000002:abnormalities / Q000033:anatomy & histology*; D006801:Humans; D013126:Spinal Nerve Roots / Q000002:abnormalities / Q000033:anatomy & histology