Anatomical Variations of the Temporomesial Structures in Normal Adult Brain - A Cadaveric Study

BACKGROUND: Despite significant evolutional, functional, and clinical interest, the anatomical variations of the temporomesial structures in cadaveric samples have received little attention. This study was undertaken to document the anatomical variations observed in the temporal lobe of human brain with emphasis on the structures present in temporomesial region. MATERIALS AND METHODS: Using 26 postmortem cadaveric cerebral hemispheres (13 right and 13 left hemispheres), several neurosurgically significant mesial structures were studied by blunt dissection under the operating microscope. The observed surface-based qualitative variations and right-left asymmetries were tabulated under well-defined, moderately defined, and ill-defined classification. RESULTS: Among the areas, uncus (100%), limen insulae (88.4%), rhinal sulcus and hippocampus (81%), intralimbic gyrus (77%), Heschl's gyrus (73%), gyrus ambiens, semilunar gyrus, sulcus semiannularis, and calcar avis (69.2%) were well defined, and band of Giacomini (38.4%) was found to be distinctly ill-defined areas in the list. Further, our analysis confirmed the presence of consistent left-greater-than-right asymmetry in all the areas of interest in temporal region under well-defined category. Rightward asymmetry was noticed in moderately defined and ill-defined classification. However, no asymmetry was detected in the uncal region. P value for all the obtained results was >0.05. CONCLUSION: Our study offers a preliminary anatomic foundation toward the better understanding of temporal lobe structures. These variations may prove valuable to neurosurgeons when designing the appropriate and least traumatic surgical approaches in operating the temporomesial lesions.