A bronchopulmonary segment is a portion of lung supplied by a specific segmental bronchus and its vessels. These arteries branch from the pulmonary and bronchial arteries, and run together through the center of the segment. Veins and lymphatic vessels drain along the edges of the segment. The segments are separated from each other by layers of connective tissue that forms them into discrete anatomical and functional units. This separation means that a bronchopulmonary segment can be surgically removed without affecting the function of the others.