MEDICAL BIOLOGY, HUMAN ANATOMY, PHYSIOLOGY AND PATHOLOGY - Y.I. Fedonyuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

SECTION 6. THE RESPIRATION PROCESS AND ITS PATHOLOGY

PRINCIPAL BRONCHI

At the level of the fifth thoracic vertebra, the Trachea bifurcates into two principal Bronchi—right and left—which approach the hilum of the lung. The right bronchus is wider yet shorter than the left, containing 6-8 cartilaginous rings, whereas the left contains 9-12. It has a more vertical orientation, appearing as a direct continuation of the trachea. The mucous membrane of the bronchi and trachea shares an identical Structure.

The Lungs (pulmones) (derived from the Greek pneumon, whence Pneumonia—inflammation of the lungs) are located within the thoracic cavity on either side of The Heart and are enveloped in a serous membrane, the Pleura, which forms two closed pleural sacs around them. The lungs are cone-shaped (Fig. 6.6), with their base resting against the Diaphragm and their apex extending 2-3 cm above the clavicle into the neck region. Three surfaces are distinguished in the lungs: costal (convex, adjacent to the Ribs), diaphragmatic (the base, resting on the diaphragm), and mediastinal (the medial surface facing the Organs of the Mediastinum). The mediastinal surface features the hilum of the lung, through which the principal bronchus, pulmonary artery, and nerves enter, and from which two Pulmonary Veins and Lymphatic vessels exit. All these structures comprise the ROOT of the lung.

Class="center">

Fig. 6.6. Trachea, principal bronchi, and lungs

Each lung is divided by fissures into lobes. The anterior border of the left lung features the cardiac notch, the site where the Pericardium (heart sac) comes into contact with it.