lec10.pdf

Thoracic cavity Dr. Harith Haitham orthopedic surgeon (F.I.C.M.S.)  Lungs  The lungs are situated so that one lies on each side of the mediastinum. They are therefore separated from each other by the heart and great vessels and other structures in the media...

Thoracic cavity Dr. Harith Haitham orthopedic surgeon (F.I.C.M.S.)  Lungs  The lungs are situated so that one lies on each side of the mediastinum. They are therefore separated from each other by the heart and great vessels and other structures in the mediastinum.  Each lung has a blunt apex, which projects upward into the neck for about (2.5 cm) above the clavicle; a concave base that sits on the diaphragm; a convex costal surface,which corresponds to the concave chest wall; and a concave mediastinal surface, which is molded to the pericardium and other mediastinal structures.  At about the middle of this surface is the hilum, a depression in which the bronchi, vessels, and nerves that form the root enter and leave the lung. The root of the lung is formed of structures that are entering or leaving the lung. It is made up of the bronchi , pulmonary artery and veins, lymph vessels, bronchial vessels, and nerves. Lobes and Fissures  Right Lung The right lung is slightly larger than the left and is divided by the oblique and horizontal fissures into three lobes: the upper, middle, and lower lobes. The obliquefissure runs from the inferior border upward and backward.  Left Lung The left lung is divided by a similar oblique fissure into two lobes: the upper and lower lobes. There is no horizontal fissure in the left lung. Bronchopulmonary Segments  The bronchopulmonary segments are the anatomic, functional , and surgical units of the lungs.  The main characteristics of a bronchopulmonary segment may be summarized as follows:  It is a subdivision of a lung lobe.  It is pyramid shaped, with its apex toward the lung root.  It is surrounded by connective tissue.  It has a segmental bronchus, a segmental artery, lymph vessels, and autonomic nerves.  The segmental vein lies in the connective tissue between adjacent bronchopulmonary segments.  Because it is a structural unit, a diseased segment can beremoved surgically.  On entering a bronchopulmonary segment, each segmental bronchus divides repeatedly. The smallest bronchi divide and give rise to bronchioles, which are