Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

Nose and Paranasal (Accessory_) SinusesThe nose consists of the two nasal cavities formed by the maxilla and palatine bones and the nasal,frontal, ethmoid, and sphenoid bones. On the lateral walls are three bony structures, one above theother, which are called conchae (superior, middle and inferior), so-called because they resembleshells. They may also be referred to as turbinates. The external orifices of the nose are the nostrils;the posterior orifice, or the opening into the nasopharynx, is called the choana. The nasal cavitiesare lined with mucous membrane.The nose serves as a passageway for air going to and coming from the lungs. Air passes throughthe nose and, then, into the nasopharynx. The nose filters the air of certain impurities, warms it, andmoistens it. In addition, the nose can detect the presence of certain types of chemicals which mightbe irritating to the mucous lining of the respiratory tract. The nose serves also as the organ for thesense of smell. Olfactory (odor) receptors are located in the nasal mucosa. The nose aids also inphonation (the making of vocal sounds).The paranasal sinuses are air cavities lined with mucous membrane. The frontal sinuses arelocated in the bone of the forehead above the orbital cavities. The ethmoid sinuses are made up ofsmall air cells located between the upper nasal cavities and the orbits. The sphenoid sinuses arewedge-shaped sinuses in the bone at the back of the orbital cavities. The maxillary sinuses (antrumof Highmore) are located in the upper jawbone.The external and internal carotid arteries supply blood to the nose and the paranasal sinuses.venous blood returns to the internal and external jugular veins.TheThe lymphatic vessels from the nose and the paranasal sinuses enter the retropharyngeal,submental, submandibular (submaxillary), and the internal jugular (upper and lower deep cervical)lymph nodes.Malignant TumorsWhile tumors of the nasal cavities are rare, the most common type is squamous cell (epidermoid)carcinoma. Other types which occur less frequently are adenocarcinoma, adenoid cystic carcinoma,melanoma, and lymphoma. A malignant tumor known as esthesioneuroblastoma or esthesioneuroepithelioma,which arises in the olfactory nerve, will be found occasionally in the nasalcavities.Ninety percent of the neoplasms of the paranasal sinuses are located in the maxillary sinuses.Histologically, the tumors are similar to those found in the nasal cavities.135