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Maxillary sinus Dr /Abdel-latif Galal Lecturer of oral Medicine& Periodontology Introduction Paranasal Sinuses (PNS) are air containing bony spaces around the nasal cavity There are 4 pairs of paranasal sinuses (bilaterally) Maxillary air sinus Frontal air sinus, Ethm...

Maxillary sinus Dr /Abdel-latif Galal Lecturer of oral Medicine& Periodontology Introduction Paranasal Sinuses (PNS) are air containing bony spaces around the nasal cavity There are 4 pairs of paranasal sinuses (bilaterally) Maxillary air sinus Frontal air sinus, Ethmoidal air sinus Sphenoidal air sinus Definition “Maxillary sinus is the pneumatic space that is lodged inside the body of the maxilla. ”Maxillary Sinus Previously called as Maxillary Antrum DEVELOPMENT Maxillary sinus is the first of the PNS to develop. 4th week I.U.L. In its development M.Sinus is: Tubular at birth Ovoid in childhood Pyramidal in adulthood with the base of the pyramid forming the lateral nasal wall and apex at the root of the zygoma Arterial supply Branch of third part of maxillary artery (pterygopalatine part) Posterior superior alveolar artery Infra-orbital artery Greater palatine artery. Venous drainage Anteriorly- Facial vein Posteriory- Pterygoid venous plexus Infection from the maxillary sinus may spread to involve cavernous sinus via any of its draining veins as the pterygoid plexus communicates with the cavernous sinus by EMISSARY VEIN Nerve supply 1.Anterior superior alveolar n 2. Middle superior alveolar n 3. Posterior superior alveolar n 4. Infra-orbital nerve Lymph drainage  Submandibular lymph nodes  Deep cervical lymph node  Retro pharyngeal lymph Nodes Microscopic Features The maxillary sinus is lined with a mucous membrane of the respiratory type. The antral mucous membrane is formed of:  An epithelial layer resting on a basement membrane.  A subepithelial connective tissue layer Epithelium Lined by Pseudostratified Columnar Ciliated epithelium Most numerous cells -Columnar ciliated cells Additional cells- Basal cells, Columnar non-ciliated cells, Goblet cells Ciliated Cells The cilia is composed of microtubules & provide mobile apparatus to the sinus epithelium which moves the debris, microorganisms, and the mucous film lining the epithelial surface of the sinus into the nasal cavity through the ostium. Goblet Cells It is mucous synthesizing and secreting cells. It resembles an inverted wine glass. The subepithelial connective tissue layer It is formed of connective tissue cells, and intercellular substance of collagen bundles and few elastic fibers and it is moderately vascular. The lamina propria contains mixed glands formed of serous and mucous acini or mixed acini as well as myoepithelial cells. Clinical significance Maxillary sinusitis Is inflammation of the maxillary sinuses. from history taking symptoms of sinusitis are headache, and fouls smelling, nasal or pharyngeal discharge, possibly with some systemic signs of infection such as fever and weakness. The skin over the involved sinus can be tender, hot, and even reddened due to the inflammatory process in the area. On radiographs, there is opacification (or cloudiness) of the usually translucent sinus due to retained mucus. Cancer Carcinoma of the maxillary sinus may invade the palate and cause dental pain. It may also block the nasolacrimal duct. Spread of the tumor into the orbit causes proptosis. Maxillary sinus cancer can be spread to the brain and lymph nodes. Age With age, the enlarging maxillary sinus may even begin to surround the roots of the maxillary posterior teeth and extend its margins into the body of the zygomatic bone. If the maxillary posterior teeth are lost, the maxillary sinus may expand even more, thinning the bony floor of the alveolar process so that only a thin shell of bone is present Tempromandibular joint  Introduction The temporomandibular joint (TMJ) is formed by the articulation between the articular eminence and the anterior part of the glenoid fossa above and the condylar head of the mandible below. The TMJ contains a fibrous intra-articular disk that is interposed between the articular surfaces and functions as a shock absorber. HISTOLOGY Bony structures The condyle of the mandible is composed of cancellous bone covered by a thin layer of compact bone.The trabeculae that they radiate from the neck of the mandible and reach the cortex at right angles, thus giving maximal strength to the condyle. The large marrow spaces decrease in size with progressing age as a result of noticeable thickening of the trabeculae. The roof of the glenoid fossa consists of a thin, compact layer of bone. The articular eminence is composed of spongy bone covered with a thin layer of compact bone. Areas of chondroid bone are commonly seen in the articular eminence, and in rare cases islands of hyaline cartilage are found. Articular disk: In young individuals the articular disk is composed of dense fibrous tissue. The fibrous tissue covering the articular eminence, the mandibular condyle, and the large central area of the disk, is devoid of blood vessels and nerves and thus has limited reparative ability. CLINICAL CONSIDERATIONS The term myofacial pain dysfunction syndrome is used to indicate a dysfunction of the TMJ. It is characterized by: Masticatory muscle tenderness (lateral pterygoid , temporalis, medial pterygoid, and masseter). Limited opening of the mandible (< 37 mm). Joint sounds. This symptom complex is seen more often in females than in males. Its cause is usually spasm of the masticatory muscles. Since the condition may be related to stress, treatment should be as conservative as possible.