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A bronchopulmonary segment, sometimes called a tertiary bronchus, is the portion of the airway that delivers oxygen to the smallest parts of the lungs where the exchange of oxygen with carbon dioxide occurs during respiration. There are 18 to 20 different bronchopulmonary segments located within a single set of lungs. The left lung has an upper and lower lobe that each contain four bronchopulmonary segments. In the three lobes of the right lung, there are ten bronchopulmonary segments. Each segment is able to function independently of the part next to it, allowing the removal of the diseased lung tissue without changing the functionality of the adjacent segments.
The bronchus is made of a muscular hollow tube lined with respiratory epithelium. Small pieces of hyaline cartilage provide structural support for the smooth muscle tissue that forms the tubing. Located within the center space of each bronchopulmonary segment is a bronchial artery and a pulmonary artery. The veins and lymphatic vessels that supply each of the segments run along the outside of the tube shaped structure. In between the segments are very thin layers of connective tissue that separate the bronchus into individual sections.
Most people have eight segments in the left lung; however, a few people may have as many as 10 individual segments. Four bronchopulmonary segments located in the upper lobe of the left lung are named according to their location in that lobe of the lung. The superior lingular segment and the inferior lingular segment are positioned on top of one another. An anterior segment is located towards the front of the upper portion of the left lung. Behind the anterior segment is the apicoposterior bronchopulmonary segment.
Underneath the lung’s left upper lobe is the lower lobe of the lung. Towards the front and middle of the lower lung is the anteromedial bronchopulmonary segment. Above the anteromedial segment is the superior segment. The posterior segment is located towards the lower back of the lung. A lateral segment provides the passageway for air to travel to the outer side of the left lung.
Ten bronchopulmonary segments are found within the three lobes of the right lung. The upper lobe contains the apical, posterior, and anterior segments. In the middle lobe, a medial and lateral segment provides the pathway for air into the lungs. Inside the lower right lobe, five bronchopulmonary segments have been identified. These are the known as the superior, anterior, medial, posterior, and lateral segments of the right lung’s lower lobe.
Diseases of the bronchopulmonary segments may be diagnosed after a thoracic computerized tomography (CT) scan is performed. A segment can be identified by the anatomical structures specific to the bronchopulmonary segments, such as segmental arteries and bronchi. Diseased or malfunctioning bronchopulmonary segments may be surgically removed without impairing the functionality of the remaining segments.