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Maxillary Sinus Dr Sandeep Gupta Oral Pathologist Maxillary Sinus  Maxillary Sinus (Antrum of Higmore) The maxillary sinus is a pneumatic space. It is the largest bilateral air sinus located in the body of the maxilla It opens in the...

Maxillary Sinus Dr Sandeep Gupta Oral Pathologist Maxillary Sinus  Maxillary Sinus (Antrum of Higmore) The maxillary sinus is a pneumatic space. It is the largest bilateral air sinus located in the body of the maxilla It opens in the middle nasal meatus of the nasal cavity with single or multiple openings are termed ostium maxillare, which found in a recess called hiatus semilunaris.. The average dimensions of the sinus are approximately The average capacity of the 3.5 (anteroposterior) x maxillary sinus is about 15 ml 3.2 (height) x 2.5 (width) cm  Development They develop at the third month of intrauterine life, in the place existing between the oral cavity and the floor of the orbit. They develop as evagination of the mucous membrane of the lateral wall of the nasal cavity at the level of the middle nasal meatus forming a minute space that expands primarily in an inferior direction into the primordium of the maxilla. The maxillary sinus enlarges variably and greatly by pneumatization until it reaches the adult size by the eruption of the permanent teeth. Growth of Maxillary sinus  Growth of Maxillary sinus Enlargement of the maxillary sinus is consequent to facial growth. Growth of the sinus slows down with decline of facial growth during puberty but continues throughout life. The maxillary sinuses are the only sizable sinuses present at birth. At birth they have the size of a small lima bean measuring about 8X4 mm, and are situated with their longer dimension directed anteriorly and posteriorly. Anatomy: The maxillary sinus varies greatly in size, shape and position not only in different individuals but also in different sides of the same individual. It is pyramidal in shape having a base, an apex and four walls: The base: lateral wall of the nasal cavity. The apex: directed laterally towards the zygomatic process of the maxilla.  Anatomy The four walls: Anterior wall: facial surface of the maxilla. Posterior wall: infratemporal surface of the maxilla. Roof: floor of the orbit. Floor: alveolar process of the maxilla. Function of the maxillary sinus: 1. Lightening the weight of the skull. 2. Resonance of voice. 3. Olfactory and respiratory modulations through regulation of the air pressure within the sinus during respiration. 4. Inspired air conditioning. 5. Craniofacial protection against mechanical trauma. 6. Production of the bactericidal enzyme (lysozyme) which may be significant in protection against bacterial infection of the nasal mucosa. Opening of Maxillary Sinus Opening of Maxillary Sinus Opens into the nasal cavity through the ostium, an opening found on the highest part of the medial wall of the sinus top of the sinus, located within the hiatus semilunarisin the middle meatus of the nasal cavity  FLOOR OF THE SINUS The permanent teeth: First molar. Second and third molars. Second and first premolars. Rarely the canine. The Deciduous teeth: D E Rarely C  Histology of the maxillary sinus: The maxillary sinus is lined with a mucous membrane of the respiratory type. However it is somewhat thinner than that lining the nasal cavity. The antral mucous membrane is formed of: An epithelial layer resting on a basement membrane. A subepithelial connective tissue layer. Histology of the maxillary sinus: Composed predominantly of pseudostratified columnar ciliated cells derived from the olfactory epithelium of the middle nasal meatus, in addition to columnar non ciliated cells, basal ells and mucous producing and secreting goblet cells.  Histology of the maxillary sinus: The goblet cell is a unicellular gland, it is mucous synthetizing and secreating cells.  Lamina Propriya/connective tissue Loose collagen bundles, very few elastic fibers Serous and mucous glands (secretions reach sinus lumen thru excretory ducts which pierce the basal lamina Blood vessels Nerve fibers (myelinated and non-myelinated Clinical consideration Maxillary sinusitis Oro-antral fistula/communication Cyst and tumors Thank You