Читать книгу Understanding Anatomy and Physiology in Nursing - John Knight - Страница 158

The right primary bronchus is angled at approximately 20 to 30 degrees to the trachea, while the left primary bronchus is angled at between 45 and 55 degrees. This means that foreign objects entering the trachea are more likely to end up in the right bronchus and right lung than the left. As in the trachea, the primary bronchi are reinforced and held open by cartilaginous rings, but rather than being C-shaped, these are complete rings. As the bronchi subdivide, becoming smaller bronchi and bronchioles, the cartilage rings are exchanged for irregular cartilaginous plates. The right lung consists of three lobes and the left lung two (Figure 4.4).

The primary bronchi divide to form the lobar bronchi with each supplying a lobe of the lungs. The subdividing branching structure of the bronchial tree continues into each lung lobe, with each successive division (generation) of airway smaller than the one before.