Inferior lobe of right lung

At a glance

English

Inferior lobe of right lung

Latin (TA2)

Lobus inferior pulmonis dextri

System

Respiratory

Region

Thorax

Side

Single, on the midline

About the inferior lobe of right lung

The inferior (lower) lobe makes up the back and base of the right lung. It is separated from the upper and middle lobes by the oblique fissure, which starts high on the back of the lung, about level with the spine of the third or fourth thoracic vertebra, and runs downwards and forwards round the side of the chest to reach the lower border near the sixth costal cartilage. Everything behind and below that line belongs to the lower lobe, so although the lobe forms only a small part of the front view of the lung, it fills most of the back of the right chest.

Its base is deeply hollowed where it sits on the right dome of the diaphragm, with the liver below the diaphragm. Its medial surface lies against the vertebral column, the oesophagus and the inferior vena cava, and its posterior part reaches down into the costodiaphragmatic recess of the pleura when the lung is fully expanded.

The lobe is ventilated by the right inferior lobar bronchus, the continuation of the intermediate bronchus. Its first branch, to the superior segment, leaves from the back; the rest of the trunk gives the four basal segmental bronchi, medial, anterior, lateral and posterior. So the lobe has five bronchopulmonary segments. Branches of the right pulmonary artery follow the bronchi, and blood returns by the right inferior pulmonary vein.

Gravity makes the lower lobes the most perfused and, in an upright person, the most likely to receive inhaled material, especially on the right where the airway runs straight down. Aspiration in someone lying on the back tends to reach the superior segment. Pneumonia and collapse of this lobe hide the outline of the right half of the diaphragm on X-ray, and fluid in the pleural space collects first around its base. Listening to the lower lobes is done mainly from the back.

Function and supply

Function

Carries out gas exchange in the back and base of the right lung, the region with the greatest blood flow and ventilation in the upright body.

Nerve supply

Pulmonary plexus, from vagal and sympathetic fibres, with visceral sensory fibres for stretch and cough reflexes.

Blood supply

Lower-lobe branches of the right pulmonary artery for gas exchange and the right bronchial artery for the tissue; drained by the right inferior pulmonary vein.