Variation in brachial plexus formation, branching pattern and relation with major vessels.

Background: Anatomical variations in the formation, branching pattern and relations of the brachial plexus have been described in humans by many authors; however these have not been extensively catalogued. The aim of the study was to describe variations in brachial plexus formation, branching pattern and relation with major vessels. Methods: This study included thorough dissection of 60 brachial plexuses which belonged to 30 cadavers (male: female ratio = 28:02 ) with age range of 20-60 years, obtained from the Department of Anatomy, College of Medical Sciences (CMS-TH), following standard guidelines. Results: Out of 60 limbs dissected in present study, the variation in formation was found in 20 limbs (33.3%), out of which 12 limbs (20%) had variations in the trunk and 8 limbs (13.3%) had variations in the cord, remaining 40 limbs (66.6%) were normal in the formation of brachial plexus. Normal branching pattern of the posterior cord was encountered in 52 (86.67%) limbs, the remaining 8 (13.33%) being variants in one form or the other. The upper subscapular nerve, the thoracodorsal nerve, the lower subscapular nerve and the axillary nerve were found to arise normally in 91.66%, 96.66%, 96.66% and 98.33% of the limbs respectively. Conclusion: The present study carried out on adult human cadavers revealed some rare variations in the formation, branching pattern and relations of the brachial plexus. These variations are of clinical significance for the surgeons, radiologists and the anesthesiologists.

Agenesis of Gall Bladder: Its Emryological Basis and Clinical Significance.

Congenital absence of the gall bladder is a rare anomaly which may occur alone or with other malformations with incidence ranging from 0.01-0.05%. Awareness of this entity by clinicians and radiologists is essential because many of these patients present with biliary symptoms and have unnecessary operations. This presentation, coupled with the inability of standard abdominal ultrasonography to convincingly diagnose agenesis of the gallbladder, can put the surgeon in a diagnostic and intraoperative dilemma. Here we report a suspected case of chronic cholecystitis who underwent a laparoscopic cholecystectomy and was found to have a congenital absence of gall bladder and cystic duct. Standard pre-operative investigative modalities which were fallacious and misleading. The embryological basis and clinical significance have been discussed.