LUNGS
Lungs are paired organs of respiration invested by pulmonary pleura except at the hilum and the attachment of the pulmonary ligament.
For dissection videos of the right and the left lungs- watch these videos:
For detailed video of the gross features of the lungs, watch this video:
For video of bronchopulmonary segments, watch this video:
Presenting parts :
Each lung is half conical shape and presents
Apex and base
Costal and medial surfaces
Three borders – anterior, posterior and inferior
Apex :
Apex is an area above the impression of the 1st rib and its costal cartilage ( not a point)
It is situated at the root of the neck
Apex is covered by cervical pleura and by supra pleura; membrane.
Relations of the apex :
The relations are similar on both sides except on the medial side.
Infront :
Subclavian artery and vein with the scalenus anterior in between
Origin of internal thoracic artery
Behind :
Sympathetic trunk
Superior intercostals artery
First posterior intercostals vein
Laterally : scalenus medius muscle and the lower trunk of brachial plexus
Medially : ( from before backwards)
Right Lung :
Right brachiocephalic vein and right phrenic nerve
Brachiocephalic trunk
Trachea and right vagus nerve
Left Lung :
Left brachiocephalic vein
Left subclavian artery
Left edge of esophagus
Thoracic duct
Base :
It is concave and semilunar in shape related to the corresponding half of the diaphragm separated by the pleural sac.
Costal surface : It is convex and smooth separated from the lateral thoracic wall by the costal pleura and the endothoracic fascia.
It presents impressions for ribs and costal cartilages and intercostal space.
Medial surface:
It consists of two parts
Posterior – vertebral surface
Anterior – mediastinal surface
Vertebral surface : it is flat and related with bodies of upper ten thoracic vertebrae and their intervertebral discs and also posterior intercostal vessels.
Mediastinal surface : Relations of mediastinal surface differ on two sides and hence the impressions of mediastinal surface of both lungs.
Right Lung :
1)Hilum of the lung and pulmonary ligament : Hilum is the non-plural impression through which structures of the lung root enter and leave the lung.
(Note : structures in hilum same as structures in root of lung)
2 Cardiac impression( In Front of hilum) : it is a concave impression (shallow on right lung) in front of hilum and pulmonary ligament related to
mainly the anterior and right surface of right atrium
anterior surface of right auricle and
a part of anterior surface of right ventricle
3) Right phrenic nerve and pericardiophrenic vessels : Pass downwards in front of the hilum between the pericardium and mediastinal pleura.
4) From above and below the cardiac impression :
( Note: the cardiac impression is related here to right atrium and so above and below the great vessels entering it
a shallow groove lodging the terminal part of inferior vena cava from the posteroinferior part of cardiac impression.
From the upper part of cardiac impression, superior vena cava and right brachio cephalic vein.
5) Above the hilum :
Meeting the vertical superior vena caval impression, a narrow groove is present above the hilum formed by the arch of azygos vein.
6) above the groove for arch of azygos vein :
Behind the brachiocephalic vein impression, this surface is related to the brachiocephalic trunk and its branches – left common carotid and left subclavian arteries.
7) Behind the brachiocephalic trunk :
A shallow vertical groove behind the brachiocephalic trunk lodges the right side of trachea and right vagus nerve.
Behind the hilum of the right lung :
A vertical groove for the right edge of the esophagus only behind the hilum. ( as the esophagus deviates to the left above and below )
MEDIASTINAL SURFACE OF LEFT LUNG :
Hilum and the pulmonary ligament :
Structures in the hilum are the same as the structures in the root of the left lung.
Cardiac impression:
It is a deep concave impression formed by
Anterior and left surfaces of the left ventricle and left auricle.
Anterior surface of right ventricle
Left phrenic nerve and pericardiophrenic vessels pass in front of the hilum.
From the upper part of cardiac impression :
Pulmonary trunk which arises from the right ventricle lodges in a groove from the upper part of the cardiac impression.
Above the hilum
A well defined groove is present above the hilum which lodges the arch of aorta.
Behind the hilum
As a continuation of the above arched groove, a vertical groove lodging the descending thoracic aorta runs behind the hilum.
From the groove for arch of aorta
A well defined vertical groove passes above from the groove for the arch of aorta for the left subclavian artery.
Behind the groove for left subclavian artery
This part is related to the left edge of the esophagus and thoracic duct.
Esophageal groove below :
This groove continues below between the groove for descending thoracic aorta and the pulmonary ligament.
Anterior border :
It is thin and follows a costo-mediastinal reflection of pleura on the right side.
On the left side, anterior border follows the reflection up to the 4th costal cartilage and then deviates laterally for 3.5cm forming the cardiac notch which turns downwards and medially to reach the 6th costal cartilage.
Posterior border :
It is thick and round and related to the anterior margin of the heads of the upper ten ribs.
Inferior border :
It separates the base of the lung from the coastal and medial surfaces.
Lobes and fissures of the lung :
Right lung presents three lobes – upper , middle and lower separated v oblique and horizontal fissure.
Left lung presents two lobes – upper and lower lobes separated by oblique fissure.
BRONCHOPULMONARY SEGMENTS
The portion of the lung aerated by each tertiary bronchus is known as bronchopulmonary segment.
Right Lung :
Presents 10 bronchopulmonary segments
3 in upper lobe : apical, anterior posterior
2 in middle lobe : lateral, medial
5 in lower lobe : apical, anterior basal, posterior basal, medial basal, lateral basal.
Left Lung :
Presents 10 bronchopulmonary segments
5 in upper lobe : apical, anterior, posterior, upper lingular, lower lingular
5 in lower lobe : apical, anterior basal, posterior basal, medial basal, lateral basal.
APPLIED ANATOMY OF BRONCHOPULMONARY SEGMENTS :
The knowledge of the position of the bronchopulmonary segments is important for
Postural drainage of infected segment
Surgical resection of the affected segment.
The posterior segment of upper lobe and apical segment of lower lobe are the most dependent segments in supine position and hence aspiration of infected material and lung abscess are common in these segments.
PULMONARY VESSELS
Each lung is provided with one pulmonary artery from pulmonary trunk which carries the deoxygenated blood to the lungs
Two pulmonary veins from each lung terminate directly in to the left atrium.it does not carry oxygenated blood in full as it receives some deoxygenated blood from deep bronchial veins.
Bronchial vessels
Bronchial arteries :
Right lung has one bronchial artery and left lung has two bronchial arteries and they arise from descending thoracic aorta.
Conducting part up to the beginning of respiratory bronchioles is nourished by the bronchial arteries.
Bronchial veins:
They consist of two systems, superficial and deep.
Superficial veins drain into arch of azygos vein on the right side and into left superior intercoastal vein or superior hemiazygos vein on the left side.
Deep bronchial drain into one of the pulmonary veins or into the left atrium.
Lymphatic drainages :
Superficial and deep lymphatics drain into broncho pulmonary lymph nodes.
Broncho pulmonary lymph nodes drain into tracheobronchial lymph nodes and into the right and left parasternal lymph nodes.
Nerve supply :
By the anterior and posterior pulmonary plexus around the lung roots.
APPLIED ANATOMY :
Bronchogenic carcinoma occurs about 30%of malignancies and is the most common cancer in men.
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