Explain The Anatomy Of The Maxillary Sinus

Anatomy of the maxillary sinus: The maxilla consists of a variety of anatomic structures, including the maxillary sinus, the lateral nasal walls, the pterygoid plates, associated vasculature structures, and teeth. The maxillary sinus is pyramidal in shape. The base of the pyramid is the medial wall of the sinus that is also the lateral wall of the nasal cavity, and its apex is pointed towards the zygomatic bone. The roof of the sinus is also the floor of the orbit. The sinus has a non-physiologic drainage port high on the medial wall (maxillary ostium) that opens into the nasal cavity between the middle and lower nasal conchae. The maxillary sinus maintains its overall size while the posterior teeth remain in function. It is,
well known, that the sinus expands with age, and especially when posterior teeth are lost. The average volume of a fully developed sinus is about 15 ml but may range between 4.5 and 35.2 ml. The sinus cavity expands both inferiorly and laterally, potentially invading the canine region. This phenomenon is possibly the result of atrophy caused by reduced strain from occlusal function. One or more septa termed “Underwood’s septa” may divide the maxillary sinus into several recesses. The overall prevalence of one or more sinus septa is between 26.5% and 31%. And is most common in the area between the second premolar and first molar. Edentulous segments have a higher prevalence of sinus septa than dentate maxillary segments. The sinus is lined with respiratory epithelium (pseudo-stratified ciliated columnar epithelium) that covers a loose, highly vascular connective tissue. Underneath the connective tissue, immediately next to the bony walls of the sinus, is the periosteum. These structures (epithelium, connective tissue, and periosteum) are collectively referred to as the Schneiderian membrane.