Tuy nhiên, do độ phân giải tương phản cao, màng phổi bình thường có thể được quan sát trên hình ảnh CT (Hình ). Khí quản là một ống định hướng theo chiều dọc (đo lường khoảng 13 cm chiều dài), mà bắt đầu dưới sụn cricoid và mở rộng đến mức gần đúng của các góc sternal nơi bifurcates. | The chest wall and ribs JONATHAN d. berry and sujal r. desai will not be seen on chest radiograph. However because of the superior contrast resolution the normal pleura may be visualized on CT images Fig. . The trachea is a vertically orientated tube measuring approximately 13 cm in length which commences below the cricoid cartilage and extends to the approximate level of the sternal angle where is bifurcates. In cross-section the outline of the trachea may vary from being oval to a D-shape depending on the phase of breathing cycle. Anteriorly and laterally the trachea is bounded by hoops of hyaline cartilage but posteriorly there is a relatively pliable membrane. On a chest radiograph the trachea is seen as a tubular region of lucency in the midline as it passes through the thoracic inlet Fig. . At the level of the aortic arch there may be slight but entirely normal deviation of the trachea to the right. At the level of the carina the trachea divides into right and left main bronchi the former is shorter wider and more vertically oriented than its counterpart on the left Fig. . Each main bronchus gives rise to lobar bronchi which divide to supply the bronchopulmonary segments in each lobe. Individual bronchopulmonary segments are not readily identified on chest radiography or CT but it is worth revising the anatomy because segmental Fig. . Targeted view of the left lower zone on CT showing normal thin pleura arrow . Fig. . PA chest showing the characteristic tubular lucency of the trachea arrowheads . The normal and minimal deviation of the trachea to the right is noted at the level of the aortic arch AA . Fig. . Targeted and magnified view of the tracheal carina asterisk . The right main bronchus thin arrows is shorther and more vertically orientated than the left thick arrows . airways and arteries can be seen particularly well on CT images and such information may be important to clinicians. On the right there are ten segments three in the
