Cadaveric Study of Variation in the Formation of Trunks of Brachial Plexus, Embryological Basis and its Clinical Significance

ABSTRACT

Background: Brachial plexus is the plexus of nerves that supplies the upper limb. Variations in the branches of brachial plexus are common but variations in the roots and trunks are very rare. Methods: Here, we report one of such rare variations in the formations of the upper trunk, middle trunk, and lower trunk of the brachial plexus in the right and left upper limb of a male and female cadaver. Results: In the present study1 limb (1.6%), there was absence of the upper trunk on the left side of a male cadaver with approximate age of 20 years. And In 1 limb (1.6%), upper trunk of the brachial plexus was found unilaterally on the right side of a male cadaver aged approximately 55 years. the upper trunk was present in 2 limbs (3.3%), both on the right side of male cadavers with approximate age of 55 and 50 years In both cases, C5 and C6 roots were split in anterior and posterior divisions (Figure No. 5). Both anterior divisions joined to give origin to an “anterior superior trunk” and both posterior divisions joined to give origin to a “posterior superior trunk”. These trunks joined to give origin to the superior (upper) trunk. In 2 limbs (3.3%) The middle trunk was absent. in the right upper limb (1.6%) of a male cadaver with approximate age of 35 years the lower trunk was formed by the union of ventral rami of C7, C8 and T1 nerve roots. Conclusions: The knowledge of variations in the formation of brachial plexus is very useful for the anatomists, radiologists, anesthesiologists, neurosurgeons and orthopedic surgeons.