Fissures divide the lungs into lobes
Each lung has an oblique fissure, separating the upper lobe from the lower lobe on the left and the upper and middle lobes from the
lower lobe on the right
The right lung has a horizontal fissure, separating the middle lobe from the upper lobe on the right
The oblique fissure runs from the 2nd thoracic vertebra posteriorly to the 6th costal cartilage anteriorly, or along the medial border of the
scapula when the arm is raised above the head.
The horizontal fissure runs from the oblique fissure at the midaxillary line along the 4th rib to its costal cartilage anteriorly.
The anterior margin of the left lung has an indentation-the cardiac notch, which often creates a thin process in the upper lobe called the
lingula.
Each lung has three surfaces:
Costal
Mediastinal
Diaphragmatic
Each lung is connected to the mediastinum by the root of the lung.
Lung root contains:
Main stem or lobar bronchi
Pulmonary vessels and bronchi.
Bronchial vessels, lymphatics, and autonomic nerves.
The lung root is surrounded by a pleural sleeve, from which extends the pulmonary ligament inferiorly.
The pulmonary ligamentpage 106
page 107Bronchopulmonary segments
The trachea bifurcates into two main stem bronchi, right and left, at the level of the T4/5 intervertebral disc (also the sternal angle of Louis).
The carina is the keel-like ridge between the two openings of the main stem bronchi.
The right main stem bronchus divides into upper and lower lobar bronchi before reaching the substance of the right lung.
The main bronchi branch to form the bronchial tree.
There are three lobar bronchi on the right: upper, middle, and lower
There are two lobar bronchi on the left: upper and lower
Each lobar bronchus branches into segmental bronchi that supply a bronchopulmonary segment.
A bronchopulmonary segment
Is a pyramidally shaped section of the lung with its base covered by visceral pleura
Is separated from adjacent segments by connective tissue septa
Is names for the segmental bronchus that supplies it
Has its own bronchus and segmental branch of the pulmonary artery
Each bronchopulmonary segment can be surgically resected, independent of adjacent segments
The right lung has 10 bronchopulmonary segments
Upper lobe: Apical
Anterior
Posterior
Middle lobe: Medial
Lateral
Lower lobe: Superior
Anterior basal
Posterior basal
Medial basal
Lateral basal
The left lobe has 8 to 10 bronchopulmonary segments
Upper lobe: Apical (may be combined with posterior to form apicoposterior)
Posterior
Anterior
Superior lingular
Inferior lingular
Lower lobe: Superior
Anterior basal (may be combined with medial to form anteromedial basal)
Medial basal
Lateral basal
Posterior basal
The right main stem bronchus is wider and shorter than the left one and descends in a more vertical plane, so aspirated foreign objects are
more likely to lodge in it or one of its branches
Because the posterior segmental bronchus of the right lower lobe runs directly posterior, foreign objects that are inhaled when the person is
lying down, such as food, may end up in this segmental bronchus.Vasculature of the lungs