Left lower lobe

Theleft lower lobe (LLL) is one of two lobes in theleft lung.  It is It is separated from theleft upper lobe by the leftoblique fissure and subdivided into fourbronchopulmonary segments segments.

Gross anatomy

Location and structure

The LLL lies in the posterior and lower aspect of the left hemithorax and contains 4 four bronchopulmonary segments:

• superior segment
• anteromedial segment
• lateral segment
• posterior segment

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

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

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 leftbronchial arteries

Venous drainage

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

Left bronchial veins drain into theaccessory hemiazygos vein or theleft superior intercostal vein.

Lymphatic drainage

The superficial subpleurasubpleural 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,

Innervation

• parasympathetic fibres from thevagus nerve (CN X)
• sympathetic fibres from the paravertebralsympathetic trunks

Related pathology

• LLL collapse
• LLL consolidation