Anatomy, Histology, and Embryology
ANATOMY, HISTOLOGY, 1 AND EMBRYOLOGY An understanding of the anatomic divisions composed of the vomer. This bone extends from of the head and neck, as well as their associ- the region of the sphenoid sinus posteriorly and ated normal histologic features, is of consider- superiorly, to the anterior edge of the hard pal- able importance when approaching head and ate. Superior to the vomer, the septum is formed neck pathology. The large number of disease by the perpendicular plate of the ethmoid processes that involve the head and neck area bone. The most anterior portion of the septum is a reflection of the many specialized tissues is septal cartilage, which articulates with both that are present and at risk for specific diseases. the vomer and the ethmoidal plate. Many neoplasms show a sharp predilection for The supporting structure of the lateral border this specific anatomic location, almost never of the nasal cavity is complex. Portions of the occurring elsewhere. An understanding of the nasal, ethmoid, and sphenoid bones contrib- location of normal olfactory mucosa allows ute to its formation. The lateral nasal wall is visualization of the sites of olfactory neuro- distinguished from the smooth surface of the blastoma; the boundaries of the nasopharynx nasal septum by its “scroll-shaped” superior, and its distinction from the nasal cavity mark middle, and inferior turbinates. The small su- the interface of endodermally and ectodermally perior turbinate and larger middle turbinate are derived tissues, a critical watershed in neoplasm distribution. Angiofibromas and so-called lym- phoepitheliomas, for example, almost exclu- sively arise on the nasopharyngeal side of this line, whereas schneiderian papillomas, lobular capillary hemangiomas, and sinonasal intesti- nal-type adenocarcinomas almost entirely arise anterior to the line, in the nasal cavity.
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