Maxillary Sinus Anatomy

Paranasal Sinuses

• There are 4 pairs of paranasal sinuses: maxillary, frontal, ethmoidal, and sphenoidal.

Maxillary Sinus

• Definition: pneumatic space inside the body of the maxilla.
• Development: first to develop, starts as a tubular structure at birth, becomes ovoid in childhood, and pyramidal in adulthood.
• Arterial supply: branches from the maxillary artery (pterygopalatine part), including posterior superior alveolar artery, infra-orbital artery, and greater palatine artery.
• Venous drainage: anteriorly through the facial vein and posteriorly through the pterygoid venous plexus, which communicates with the cavernous sinus via an emissary vein.
• Nerve supply: anterior superior alveolar nerve, middle superior alveolar nerve, posterior superior alveolar nerve, and infra-orbital nerve.
• Lymph drainage: submandibular lymph nodes, deep cervical lymph nodes, and retropharyngeal lymph nodes.

Microscopic Features

• Lined with a mucous membrane of the respiratory type.
• Epithelium: pseudostratified columnar ciliated epithelium with columnar ciliated cells, basal cells, columnar non-ciliated cells, and goblet cells.
• Cilia: composed of microtubules, providing a mobile apparatus to move debris and microorganisms out of the sinus.
• Goblet cells: mucous synthesizing and secreting cells.

Clinical Significance

• Maxillary sinusitis: inflammation of the maxillary sinus, symptoms include headache, foul-smelling nasal or pharyngeal discharge, fever, and weakness.
• Cancer: carcinoma of the maxillary sinus may invade the palate and cause dental pain, block the nasolacrimal duct, and spread to the brain and lymph nodes.
• Age: with age, the maxillary sinus expands, surrounding the roots of the maxillary posterior teeth and extending into the zygomatic bone.

Temporomandibular Joint (TMJ)

• Formed by the articulation between the articular eminence and the condylar head of the mandible.
• Contains a fibrous intra-articular disk that functions as a shock absorber.

HISTOLOGY

• Bony structures: condyle of the mandible composed of cancellous bone covered by a thin layer of compact bone, with trabeculae radiating from the neck of the mandible.
• Articular disk: composed of dense fibrous tissue, devoid of blood vessels and nerves.

Clinical Considerations

• Myofacial pain dysfunction syndrome: characterized by masticatory muscle tenderness, limited opening of the mandible (< 37 mm), and joint sounds, more common in females.

Learn about the maxillary sinus, its definition, and its relationship to other paranasal sinuses. This quiz covers the basics of maxillary sinus anatomy.