A four trunked brachial plexus and a post fixed brachial plexus: A conjunction or a co‐incidence?: Report of three cases

Abstract

The anatomical variations of the brachial plexus in humans have clinical significance for surgeons, radiologists, and anatomists. In a study of 60 brachial plexuses, four trunked brachial plexuses were encountered in three limbs (two female and one male), all of them being post fixed and on left side of cadavers. The third trunk in all these limbs gave rise to two anterior divisions (upper and lower) and one posterior division. In two limbs belonging to the female sex, the upper anterior division joined with the anterior division of the second trunk to form the lateral cord while its lower anterior division joined with the anterior division of the fourth trunk to form the medial cord. In the sole male limb, along with the third trunk, the fourth trunk also divided into upper and lower anterior divisions. Upper anterior divisions of the third and fourth trunks joined to form the medial root of the median nerve while lower anterior divisions joined to form the ulnar nerve. No medial cord was formed as such. Further, it is inferred that in postfixed brachial plexus, there is a tendency to failure on part of T1 and T2 to join C8 which continues as the third trunk while T1 and T2 continue as the fourth trunk. Since it was seen in all postfixed brachial plexuses of the present study, it is emphasized to be given a place in the textbooks of anatomy or to conduct a study on a larger database.