Superior lobe of right lung

At a glance

English

Superior lobe of right lung

Latin (TA2)

Lobus superior pulmonis dextri

System

Respiratory

Region

Thorax

Side

Single, on the midline

About the superior lobe of right lung

The right lung is split into three lobes by two fissures, and the superior (upper) lobe is the top one. Its lower boundary is formed in front by the horizontal fissure, which separates it from the middle lobe, and behind by the upper part of the oblique fissure, which separates it from the lower lobe. It contains the apex of the lung, which climbs above the first rib to the base of the neck under the cupula of the pleura.

Like the rest of the lung it is spongy and elastic, covered by visceral pleura and moulded by its surroundings. Its costal surface faces the upper ribs. Its mediastinal surface faces the midline and carries grooves for nearby structures: the right brachiocephalic vein and superior vena cava in front, the arch of the azygos vein above the hilum, and the trachea and oesophagus behind. Its front edge is thin and sharp and reaches towards the midline behind the sternum.

The lobe is aerated by the right superior lobar bronchus, the eparterial bronchus, which leaves the right main bronchus above the right pulmonary artery. This bronchus divides into three segmental bronchi, and the lobe is divided accordingly into apical, posterior and anterior bronchopulmonary segments. Each segment has its own airway and artery and is separated from its neighbours by thin connective tissue, so a single segment can be removed surgically. Pulmonary veins run between segments rather than within them.

The upper lobe is clinically important. Its apical and posterior segments are the classic sites of reactivation tuberculosis, and a tumour at the apex can invade the brachial plexus and sympathetic chain at the root of the neck, giving arm pain and a drooping eyelid with a small pupil. Collapse of the lobe pulls the horizontal fissure upwards on a frontal X-ray. An extra azygos fissure sometimes cuts off part of the lobe as a small accessory lobe.

Function and supply

Function

Exchanges oxygen and carbon dioxide between inspired air and the blood in the uppermost part of the right lung.

Nerve supply

Pulmonary plexus: vagal fibres constrict the bronchi and increase secretion, sympathetic fibres dilate them; visceral sensory fibres carry stretch and cough reflexes.

Blood supply

Branches of the right pulmonary artery for gas exchange and the right bronchial artery for the lung tissue itself; drained by the right superior pulmonary vein.