Right lung

Pulmo dexter

Also known as: lung, right upper lobe, right middle lobe, right lower lobe, horizontal fissure, oblique fissure

The larger lung (≈55% of total lung volume), divided by the oblique and horizontal fissures into superior, middle and inferior lobes and ten bronchopulmonary segments.

Show on body map Respiratory Tract

Overview

Lobes / fissures3 lobes / 2 fissures (oblique, horizontal)

Bronchopulmonary segments10

Mass (adult male)≈625 g

Share of lung volume≈55%

Each lung is a light, spongy, cone-shaped organ with an apex that rises 2–3 cm above the medial third of the clavicle into the root of the neck, a concave base (diaphragmatic surface) resting on the diaphragm, a convex costal surface and a concave mediastinal surface containing the hilum. Borders: anterior (sharp), inferior (sharp, entering the costodiaphragmatic recess in deep inspiration) and posterior (rounded, alongside the vertebral column).

The right lung is shorter and wider than the left because the right dome of the diaphragm sits higher over the liver, and it is heavier (≈625 g vs ≈565 g in adult men). The oblique fissure runs from about the level of the T2 spinous process posteriorly (descriptions range from T2 to T4), around the chest, to the 6th costal cartilage anteriorly, separating the inferior lobe from the superior and middle lobes. The horizontal fissure runs from the oblique fissure in the mid-axillary line forward along the 4th rib and costal cartilage to the sternum, separating the superior and middle lobes. The middle lobe is therefore largely anterior and the inferior lobe largely posterior — the posterior chest examines mostly lower lobes, the anterior chest upper and middle lobes.

On the mediastinal surface, the right lung bears impressions of the right atrium (cardiac impression), SVC and right brachiocephalic vein, the arch of the azygos vein above the hilum, the oesophagus and trachea, and the IVC near the base.

Location: Right half of the thoracic cavity, within the right pleural sac, lateral to the mediastinum; apex in the root of the neck, base on the right dome of the diaphragm.

Parts & subdivisions

Superior (upper) lobe
Above the horizontal fissure; segments apical, posterior and anterior.
Middle lobe
Wedge between the horizontal and oblique fissures; lateral and medial segments; homologue of the lingula.
Inferior (lower) lobe
Below and behind the oblique fissure; superior and four basal segments.
Oblique and horizontal fissures
Lined by visceral pleura; often incomplete, allowing collateral ventilation between lobes.
Hilum and root
Eparterial bronchus superoposteriorly, pulmonary artery anterior to the bronchus, pulmonary veins anteroinferior.
Bronchopulmonary segments
Ten on the right.

Anatomy

Innervation: Pulmonary plexus at the hilum: parasympathetic fibres from the vagus (bronchoconstriction, glandular secretion, pulmonary vasodilation) and sympathetic fibres from the T1–T5 sympathetic trunk (bronchodilation via circulating adrenaline/β2, vasoconstriction); visceral afferents (stretch, irritant, J receptors, cough) travel in the vagus. The visceral pleura and lung parenchyma are insensitive to pain.
Arterial supply: Functional (pulmonary) circulation: right pulmonary artery from the pulmonary trunk delivers deoxygenated blood (≈ mean 15 mmHg); two right pulmonary veins (superior and inferior) return oxygenated blood to the left atrium. Nutritive (bronchial) circulation: usually one right bronchial artery from the third right posterior intercostal artery supplies airways, connective tissue and visceral pleura.
Venous drainage: Pulmonary veins → left atrium; bronchial veins → azygos vein (some deep bronchial veins drain into pulmonary veins).
Lymphatic drainage: Superficial (subpleural) and deep (peribronchial) plexuses → bronchopulmonary (hilar) nodes → inferior (subcarinal) and superior tracheobronchial nodes → paratracheal nodes → right bronchomediastinal trunk → right lymphatic duct or directly into the venous angle.
Relations: Medially: mediastinum (right atrium, SVC, azygos, oesophagus, trachea); inferiorly: right dome of diaphragm and, beneath it, the liver; laterally: ribs and intercostal spaces; apex: subclavian artery and vein, brachial plexus (lower trunk), stellate ganglion, first rib.

Function

Gas exchange (≈55% of total).
Filtering of venous emboli and metabolic functions of the pulmonary endothelium.
Acid–base regulation through CO2 elimination.

Clinical significance

Surface anatomy and auscultation

Inferior lung border: 6th rib in the midclavicular line, 8th rib in the mid-axillary line, 10th rib posteriorly. Right middle lobe pathology is best heard anteriorly and in the right axilla (below the 4th rib), lower lobe pathology posteriorly.

Aspiration pneumonia and lung abscess

Because the right main bronchus is more vertical, aspiration most often affects the right lower lobe (upright) or the posterior segment of the right upper lobe and superior segment of the right lower lobe (supine).

Pancoast tumour

An apical (superior sulcus) carcinoma invades the lower brachial plexus, sympathetic chain/stellate ganglion (Horner's syndrome) and sometimes the subclavian vessels.

Mnemonics

Lobes

"Right has thRee": the right lung has three lobes and two fissures; the left has two lobes and one fissure.

Test yourself

A man inhales a peanut while lying supine. Which bronchopulmonary segment is it most likely to enter?

Apicoposterior segment of the left upper lobe
Lingula
Superior segment of the right lower lobe
Anterior basal segment of the left lower lobe

Answer: Superior segment of the right lower lobe

The right main bronchus is wider, shorter and more vertical than the left, so aspirated material usually enters the right lung. In the supine position the superior segment of the lower lobe (and the posterior segment of the upper lobe) is most dependent; in the upright position material falls into the basal segments of the right lower lobe.

A smoker has ptosis, miosis and facial anhidrosis on the right, with wasting of the small muscles of the right hand. An apical lung tumour has most likely invaded the:

Cervical sympathetic chain and lower trunk of the brachial plexus
Right phrenic nerve and superior vena cava
Right recurrent laryngeal nerve
Right vagus nerve and oesophagus

Answer: Cervical sympathetic chain and lower trunk of the brachial plexus

A Pancoast (superior sulcus) tumour at the lung apex invades the stellate ganglion/cervical sympathetic chain (Horner's syndrome: ptosis, miosis, anhidrosis) and the C8–T1 roots/lower trunk of the brachial plexus (intrinsic hand muscle weakness, ulnar-side pain).