One of the most important anatomical structures in endoscopic sinus surgery during operation is middle turbinate. Early sacrifice or the absence of middle turbinate can end up patient in a grave danger of intracranial and intra orbital complications if the surgeon is not extra careful. The chapter is profusely illustrated to demonstrate on coronal, axial and Sagittal views to show close relation of all Para nasal sinuses to the orbit and skull base with “dry” and fresh cadaver dissection, correlating those parts of the anatomy to the anatomy on clinical examination with the endoscope in the nasal cavity. Further more various anatomical points are also correlated to the high definition CT scan and operative anatomy to illustrate important anatomy for the surgeon during operation. Of particular, anatomy of the ground lamella has been precisely shown and its importance to the surgeon during operation. The importance of difference between natural and accessory ostia of maxillary sinuses has been summarised in an easy to understand illustrations.