4.9: Lungs

See written notes.

Each has main bronchus, 1 pulmonary artery and 2 pulmonary veins.

L lung root

Artery superiorly, bronchus below & behind; veins anterior to and below bronchus.

R lung root

Similar to L; upper lobe bronchus and arterial branch leave main trunks outside the lung.

Fissures & lobes

Pleura penetrates to depths of fissures.

Oblique: incomplete in 50%; divides lung into upper & lower lobes.

Horizontal: in R lung; from anterior margin ® hilum, dividing middle & lower lobes.

Lingula: anteromedial aspect of L lung, corresponding to middle lobe of R lung.

Surface markings

Hilum

Behind 3^rd & 4^th cc’s at sternal margin; level with T5-7.

Lungs

As for pleura in supraclavicular region and costal walls. Inferiorly lungs lie 2 spaces above pleural reflection: MCL at 6^th rib, MAL at 8^th rib, lateral border of erector spinae at 10^th rib.

Oblique fissures

Line joining spine of T3 & 6^th rib in MCL; = line of 5^th rib, = level of vetebral border of scapula when arm fully abducted.

Divisions of bronchi

Each main bronchus ~5cm long; R shorter & more vertical than L. Carina lies to L of midline \ FB more likely to enter R lung. Lobar bronchi divide into segmental bronchi. 10 bronchopulmonary segments in each lung; 5 in lower lobes, 5 in L upper, 3 in R upper, 2 in R lower.

Blood supply

Bronchial arteries supply bronchi down to level of bronchioles. Venous drainage to azygos system.

Lymphatics

® hilar nodes ® tracheobronchial group ® mediastinal trunks ® brachiocephalic veins.