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

LHnRsThe lungs are cone-shaped organs of respiration which lie in the thoracic cavity, one on either sideof the mediastinum.The rounded upper portion of each lung is called the apex; the base is the concave lower portionresting on the diaphragm; and the hilus is the area on the medial surface through which the mainbronchus, pulmonary artery, pulmonary vein, nerves, and lymph vessels enter and leave each lung.The left lung is partially divided by a fissure into an upper and lower lobe. Projecting from the lowerportion of the left upper lobe is an area called the lingula (coded to left upper lobe). The right lungis divided by two fissures into three lobes (upper, middle, and lower).Visceral pleura or mesothelium covers the outer surfaces of the lungs and adheres to them (SeeFigure 18). Parietal pleura or mesothelium lines the thorax. The potential space between thevisceral and parietal pleura is called the (inter)pleural space or pleural cavity. The pleural spacecontains a lubricating pleural fluid which eliminates friction during the breathing process. This fluiddrains to the mediastinal nodes. When the mediastinal nodes become inflamed or involved with adisease process such as a malignancy, a pleural effusion develops. Breathing then becomes laboredand painful.Figure 18. LUNGSmloph_ju8153