LUNGSFaarah abdilahi

AMOUD COLLEGE OF HEALTH SCIENCE

Lungs

The two lungs are organs of respiration and lie on either side of the mediastinum surrounded by the right and left pleural cavities. Air enters and leaves the lungs via main bronchi, which are branches of the trachea.

Cont..

The pulmonary arteries deliver deoxygenated blood to the lungs from the right ventricle of the heart. Oxygenated blood returns to the left atrium via the pulmonary veins.

Cont..

The right lung is normally a little larger than the left lung because the middle mediastinum, containing the heart, bulges more to the left than to the right.

Each lung has a half-cone shape, with a base, apex, two surfaces and three borders .

Lungs

Each lung consists :-•Apex •Base•Costal or lateral surface •Mediastinal or medial surface.

Lungs

The base sits on the diaphragm. The apex projects above rib I and into

the root of the neck. The two surfaces-the costal surface lies

immediately adjacent to the ribs and intercostal spaces of the thoracic wall. The mediastinal surface lies against the mediastinum anteriorly and the vertebral column posteriorly and contains the comma-shaped hilum of the lung through which structures enter and leave.

Cont..

The three borders-the inferior border of the lung is sharp and separates the base from the costal surface. The anterior and posterior borders separate the costal surface from the medial surface. Unlike the anterior and inferior borders, which are sharp, the posterior border is smooth and rounded.

Lungs

Costal surface meet with the mediastinal surface at anterior border(sharp).

Has a rounded posterior border(vertebral)

Costal & mediastinal surfaces end below as the inferior border which separates them from the base.

All surfaces are covered by pleura except at the hilum.

The lungs

The lungs lie directly adjacent to, and are indented by, structures contained in the overlying area.

The heart and major vessels form bulges in the mediastinum that indent the medial surfaces of the lung; the ribs indent the costal surfaces.

Pathology, such as tumors, or abnormalities in one structure can affect the related structure.

Apex

Upper conical part lying above the thoracic inlet.

Covered by the Sibson’s fascia

Extends up to the neck of 1st rib behind, 3-4 cms above 1st costal cartilage and 2.5 cms above medial 1/3rd of clavicle.

Covered on all sides by the apical pleurae(parietal and visceral).

Relations of Apex

Anterior-Subclavian artery separated by scalenus anterior from the subclavian vein.

Posterior- Sympathetic chain,1st posterior intercostal V,superior intercostal A and 1st thoracic nerve (SVAN structures-medial to lateral in front of neck of 1st rib)

Medial- Brachiocephalic trunk , Rt brachiocephalic V

& trachea (Right apex) Left subclavian A;Lt brachiocephalic V &

esophagus + thoracic duct (Left apex)

Clinical importance of apex

Could be injured in any stab wounds of the neck or in surgical procedures like catheterization.

Apex lung sounds are best heard with the stethoscope over the medial end of the clavicle.

Poor blood supply>>cause of TB lesions (nidus for bacteria)

Base

Separated from the abdominal organs by the diaphragm.

Right lobe of liver on the right

stomach, spleen & left lobe of liver on the left.

Borders

Anterior border- from apex to base Starts 2.5 cms above the

sternoclavicular joint behind sternal angle

Extends behind body of sternum till 4th costal cartilage (Both lungs)

On right side descends till xiphisternal junction.

On the left side deviates laterally by 3.5 cms from midline in 4th space descends till 6th costal cartilage 4 cms from midline (Cardiac notch)

Cont..

Cardiac notch – area where the anterior margin and pleura deviate from midline on the anterior border of left lung.

pericardium is directly exposed to the chest wall- Area of superficial cardiac dullness

A route of entry for emergency intracardiac administration of drugs

For pericardiocentesis or a window to visualize the heart on an

echocardiography.

Inferior Border:

Extends :-

• From 6th rib in the midclavicular line (8th for pleura)

• 8th rib in the mid axillary line (10th for pleura)

• 10th rib in the posterior axillary line (12th for pleura).

Posterior (vertebral border)

• Rounded , extends from apex to base

• Separates the costal and mediastinal surfaces.

• Lies in the paravertebral gutter.

Surfaces

Costal Covered by costal (parietal) and (visceral)

pulmonary pleura with pleural sac intervening. Has impressions created by the ribs. Mediastinal 2 parts– vertebral part~~related to the thoracic vertebrae,

IV discs and structures in the paravertebral gutter.

mediastinal part~~ covered by parietal & visceral mediastinal pleurae EXCEPT at the hilum.

Structures in the mediastinum leave impressions on this surface in both lungs

Lung

Mediastinal surface right lung

Root and hilum

The root of each lung is a short tubular collection of structures that together attach the lung to structures in the mediastinum

It is covered by a sleeve of mediastinal pleura that reflects onto the surface of the lung as visceral pleura.

The region outlined by this pleural reflection on the medial surface of the lung is the hilum, where structures enter and leave

Cont..

A thin blade-like fold of pleura projects inferiorly from the root of the lung and extends from the hilum to the mediastinum. This structure is the pulmonary ligament.

It may stabilize the position of the inferior lobe and may also accommodate the down-and-up translocation of structures in the root during breathing.

Cont..

In the mediastinum, the vagus nerves pass immediately posterior to the roots of the lungs, while the phrenic nerves pass immediately anterior to them.

Within each root and located in the hilum are: apulmonary artery; two pulmonary veins; a main bronchus; bronchial vessels; nerves; and lymphatics.

Cont

Generally, the pulmonary artery is superior at the hilum, the pulmonary veins are inferior, and the bronchi are somewhat posterior in position.

On the right side, the lobar bronchus to the superior lobe branches from the main bronchus in the root, unlike on the left where it branches within the lung itself, and is superior to the pulmonary artery.

Impressions on mediastinal surfaces of left lung

1. Cardiac- Left ventricle Left auricle Infundibulum

of RV.

2. Arch of aorta over root.

3. Descending thoracic aorta

4. Esophageal- in front of lower part of pulmonary ligament

5. Apex-

•L Brachiocephalic V

•L Subclavian A

•Thoracic duct

•Esophagus.

Right lung

The right lung has three lobes and two fissures .

Normally, the lobes are freely movable against each other because they are separated, almost to the hilum, by invaginations of visceral pleura.

These invaginations form the fissures

Cont..

the oblique fissure separates the inferior lobe (lower lobe) from the superior lobe and the middle lobe of the right lung;

the horizontal fissure separates the superior lobe (upper lobe) from the middle lobe.

Left lung

The left lung is smaller than the right lung and has two lobes separated by an oblique fissure.

The oblique fissure of the left lung is slightly more oblique than the corresponding fissure of the right lung.

CONT..

During quiet respiration, the approximate position of the left oblique fissure can be marked by a curved line on the thoracic wall that begins between the spinous processes of vertebrae TIII and TIV, crosses the fifth interspace laterally, and follows the contour of rib VI anteriorly .

Cont..

As with the right lung, the orientation of the oblique fissure determines where to listen for lung sounds from each lobe.

The largest surface of the superior lobe is in contact with the upper part of the anterolateral wall, and the apex of this lobe projects into the root of the neck. The costal surface of the inferior lobe is in contact with the posterior and inferior walls.

Cont..

When listening to lung sounds from each of the lobes, the stethoscope should be placed on those areas of the thoracic wall related to the underlying positions of the lobes .

The inferior portion of the medial surface of the left lung, unlike the right lung, is notched because of the heart's projection into the left pleural cavity from the middle mediastinum.

Fissures and lobes

Both lungs have an oblique fissure.

Starts about 6 cms below the apex on the posterior border and extends downwards & forwards to meet the anterior end of the base.

Surface marking of oblique fissure

a line drawn from the spinous process of T3, around the side of the thorax to 6th rib in the mid-clavicular line

Along vertebral border of the scapula in a hyperabducted arm

Cont..

Right lung has a horizontal fissure in addition.

• Extends from the middle of the anterior border to the oblique fissure.

• Horizontal fissure divides right lung into 3 lobes:

(Upper, middle & lower lobes)

Left lung has only 2 lobes.(upper & lower)

Lingula is a small part projecting from the lower part of the cardiac notch

Cont..

The approximate position of the oblique fissure on a patient, in quiet respiration, can be marked by a curved line on the thoracic wall that begins roughly at the spinous process of vertebra TIV level of the spine, crosses the fifth interspace laterally, and then follows the contour of rib VI anteriorly .

Cont..

The horizontal fissure follows the fourth intercostal space from the sternum until it meets the oblique fissure as it crosses rib V.

The orientations of the oblique and horizontal fissures determine where clinicians should listen for lung sounds from each lobe.

Cont..

When listening to lung sounds from each of the lobes, it is important to position the stethoscope on those areas of the thoracic wall related to the underlying positions of the lobes .

The medial surface of the right lung lies adjacent to a number of important structures in the mediastinum and the root of the neck .

Cont..

These include:-- the heart, inferior vena cava, superior vena cava, azygos vein, esophagus.

Root of lungs

The hila of the lungs correspond to:• anteriorly, the level of the 3rd-4th costal cartilage

• posteriorly, the level of the T5-T7 vertebrae

One key difference between the hila is that:• on the right, the right superior lobe bronchus

divides from the right principal bronchus before the right hilum

• on the left side, the left principal bronchus does not divide until it has entered the hilum of the lung

Right hilum

B A B V

From above downwards

1. Eparterial bronchus

2. Pulmonary A

3. Hyparterial bronchus

4. Lower pulmonary vein

From before backwards

1. Upper pulmonary V

2. Pulmonary A

3. Bronchus(Hyparterial)

Left hilum

From above downwards

1. Pulmonary A

2. Bronchus

3. Lower pulmonary vein

From before backwards

1. Upper pulmonary V

2. Pulmonary A

3. Bronchus ABV

Hyparterial bronchus

Eparterial bronchus

Primary

Primary SecondaryTertiary

Broncho-Pulmonary Segments

Definition:- The portion of lung aerated by one tertiary (segmental) bronchus. It is a self contained functionally independent respiratory unit.

Features:• Subdivision of a lung lobe.

• Pyramidal in shape with the base directed towards the surface.

CONT..

• Surrounded by connective tissue.

• Contains a segmental bronchus, a segmental pulmonary artery, lymph vessels and autonomic nerves.

• Pulmonary Vein is intersegmental.

• A diseased unit can be removed surgically.

Clinical Importance of Bronchopulmonary segments

Segments more liable to infection

• Apical segment of lower lobe being the most dependent part on a supine position.

• Posterior segment of upper lobe- the arterial supply to this segment is poor.

• Infection is usually restricted to one segment except in tuberculosis and carcinoma.

• The right bronchus being wider and more straight allows foreign bodies to enter with ease and reach the middle lobe or lower lobe bronchi.

Blood Supply of lungs

Bronchial arteries supply the lung tissue till the respiratory bronchioles.

Left bronchial arteries –2 branches from thoracic aorta

Right bronchial artery from right 3rd posterior intercostal artery.

Bronchial veins are superficial and deep

Cont..

Superficial Left bronchial veins-2 in number- upper drains into left superior

intercostal vein Lower drains into acessory hemiazygos

V

Right bronchial veins –2 in number- Both drain into the azygos V Deep veins drain directly into the

pulmonary veins or left atrium.

Lymphatics of lungs

From superficial and deep.

Superficial- subpleural (visceral) bronchopulmonary at hilum.

Deep travel along bronchi and pulmonary vessels passing through pulmonary nodes bronchopulmonary nodes at hilum

All lymph leave hilum tracheobronchial nodes and then bronchomediastinal trunks.

Lymphatics of lungs

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