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Head and neck
Published in David A Lisle, Imaging for Students, 2012
The paranasal sinuses are air-filled spaces in the medullary cavities of skull and facial bones. Named from the bones in which they occur, the paranasal sinuses consist of the frontal, ethmoid, maxillary and sphenoid sinuses. Paranasal sinuses drain by small ostia into the nasal cavities. Mucociliary action within the sinuses pushes debris towards the draining ostia. While a variety of congenital anomalies and tumours may affect the paranasal sinuses, the most common indication for imaging is inflammation. Paranasal sinus inflammation may be acute or chronic, and is commonly associated with disease in the nasal passages, in particular nasal polyposis in association with allergic sinusitis.
Voxel-based modeling of airflow in the human nasal cavity
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Shinya Kimura, Takashi Sakamoto, Toshihiro Sera, Hideo Yokota, Kenji Ono, Denis J. Doorly, Robert C. Schroter, Gaku Tanaka
Figure 5 shows details of the nasal airway. In this model, though the perimeter through each cavity is almost the same, there are significant asymmetric differences in the structure of the right and left cavities, with the left cross-sectional area approximately 1.4 times larger than that in the right. This is an effect of structural differences, the nasal cycle, or reactions to allergens/infections (Eccles 2000). The nasal airways are separated by the septum, which is composed of cartilage tissue. The left and right hydraulic diameters (= 4 × area/perimeter) at the nasal valve in plane 2, where the cross-sectional area often attains a minimum, are 8.2 mm and 8.9 mm. The nasal airway extends vertically at its posterior to the nasal valve. The turbinate region consists of a slit-like common meatus connected to the superior, middle, and inferior meatus between planes 4 and 6. The upper part of the common meatus contains the olfactory epithelium, which contains sensory nerve endings for smell. Both airways join at plane 8 before the nasopharynx at plane 9. The paranasal sinuses surrounding the nasal cavity are connected via small orifices. In this study, the paranasal sinuses were excluded from the computational domain. Thus, this complex anatomy is characteristic of the nasal cavity. To estimate the geometry of the nasal cavity quantitatively, the complexity is defined as: where l is the perimeter and A is the cross-sectional area. Figure 4(d) shows the complexity distribution as a function of distance from the nose tip. The cross-section at plane 5 has the highest complexity of 37, which is equivalent to gathering this number of parallel tubes, although the nasal cavity has only two passages.