left lower lobe

Radiopaedia • CC-by-nc-sa 3.0 • de

The left lower lobe (LLL) is one of two lobes in the left lung. It is separated from the left upper lobe by the left oblique fissure and subdivided into four bronchopulmonary segments.

Gross anatomy

Location and structure

The LLL lies in the posterior and lower aspect of the left hemithorax and contains four bronchopulmonary segments:

Like all the pulmonary lobes, it is lined by visceral pleura which reflects at the pulmonary hilum where it is continuous with the parietal pleura. The left lower lobe bronchus arises as the inferiorly angled continuation of the left main bronchus to traverse the left hilum into the LLL.

The LLL is separated from the left upper lobe posterosuperiorly by the left oblique fissure.

Blood supply

Arterial supply

Like all the lobes of the lung, the LLL has dual arterial supply:

deoxygenated blood from the left lower lobar pulmonary artery
oxygenated blood from branches of the left bronchial arteries

Venous drainage

Venous drainage of newly oxygenated blood is via the right inferior pulmonary vein into the left atrium.

Left bronchial veins drain into the accessory hemiazygos vein or the left superior intercostal vein.

Lymphatic drainage

The superficial subpleural lymphatic plexus drains the lung parenchyma and visceral pleura to the bronchopulmonary (hilar) lymph nodes in the hilum.

The deep bronchopulmonary lymphatic plexus (in the bronchial submucosa and peribronchial interstitium) drains the root of the lung to hilar lymph nodes in the hilum.

The hilar lymph nodes then drain to the tracheobronchial lymph nodes.