Anatomy of Lungs 6

ANATOMYANATOMY OFOF LUNGSLUNGS

- 1. Gross Anatomy of Lungs 6. Histopathology of Alveoli 2. Surfaces and Borders of Lungs 7. Surfactant 3. Hilum and Root of Lungs 8. Blood supply of lungs 4. Fissures and Lobes of 9. Lymphatics of Lungs Lungs 10. Nerve supply of Lungs 5. Bronchopulmonary 11. Pleura segments 12. Mediastinum GROSSGROSS ANATOMYANATOMY OFOF LUNGSLUNGS

Lungs are a pair of respiratory organs situated in a thoracic cavity. Right and left lung are separated by the mediastinum.

Texture -- Spongy Color – Young – brown Adults -- mottled black due to deposition of carbon particles Weight- Right lung - 600 gms Left lung - 550 gms THORACICTHORACIC CAVITYCAVITY SHAPE - Conical Apex (apex pulmonis)

Base (basis pulmonis)

3 Borders -anterior (margo anterior) -posterior (margo posterior) - Inferior (margo inferior)

2 Surfaces -costal (facies costalis) - medial (facies mediastinus) - anterior (mediastinal) - posterior (vertebral) APEXAPEX

Blunt Grooved byb - Lies above the level of Subclavian artery anterior end of 1st Rib. Subclavian vein Reaches 1-2 cm above medial 1/3rd of clavicle. Coverings – cervical pleura. suprapleural membane

BASEBASE

SemilunarSemilunar andand concave.concave.

RestsRests onon domedome ofof Diaphragm.Diaphragm.

RightRight sidedsided domedome isis higherhigher thanthan left.left. BORDERSBORDERS

ANTERIORANTERIOR BORDERBORDER ––

1.1. CorrespondsCorresponds toto thethe anterioranterior ((CostomediastinalCostomediastinal)) lineline ofof pleuralpleural reflection.reflection.

2.2. ItIt isis deeplydeeply notchednotched inin thethe leftleft lunglung posteriorposterior toto 55th costalcostal cartilagecartilage byby thethe pericardiumpericardium andand extendsextends verticallyvertically downwardsdownwards toto formform LingulaLingula.. ThisThis isis calledcalled cardiaccardiac notchnotch(percussion(percussion inin thisthis areaarea givesgives aa dulldull notenote asas comparedcompared toto dulldull notenote obtainedobtained overover lung).lung). INFERIORINFERIOR BORDERBORDER

ThinThin andand sharpsharp

ItIt seperatesseperates thethe basebase ofof lunglung fromfrom thethe costalcostal surfacesurface andand extendsextends intointo phrenicocostalphrenicocostal sinus.sinus. POSTERIORPOSTERIOR BORDERBORDER

ThickThick andand illill defineddefined

FitsFits intointo deepdeep paravertebralparavertebral gutter.gutter.

ExtendsExtends fromfrom C7C7 toto T10.T10. SURFACES OF THE LUNG

1. Costal Surface - It is in contact with costal pleura and overlying thoracic wall. 2. Medial Surface - Posterior / Vertebral Part - Anterior / Mediastinal Part Relations of Posterior Part

1. Vertebral Part

2. Intervertebral Discs

3. Posterior Intercostal Vessels

4. Splanchic Nerves RELATIONSRELATIONS OFOF ANTERIORANTERIOR PARTPART RIGHT SIDE LEFT SIDE

1. Right atrium 1. Left ventricle 2. Small part of RV 2. Pulmonary trunk 3. SVC 3. Arch of Aorta 4. Right brachiocephalic 4. Descending thoracic vein(lower part) aorta 5. Azygos vein 5. Left Subclavian Artery 6. Esophagus 6. Thoracic duct 7. IVC 7. Left Brachiocephalic 8. Trachea Vein 9. Right vagus nerve 8. Left vagus nerve 10. Right phrenic nerve 9. Left phrenic nerve 10. Left recurrent laryngeal nerve

HILUMHILUM

ItIt isis aa largelarge depresseddepressed areaarea thatthat lieslies nearnear thethe centrecentre ofof thethe medialmedial surface.surface.

VariousVarious structuresstructures enterenter andand leaveleave thethe lunglung viavia itsits root.root. ROOTROOT OFOF THETHE LUNGLUNG

The root is enclosed in a short tubular sheet of pleura that joins the pulmonary and mediastinal parts of pleura . It extends inferiorly as a narrow fold - The pulmonary ligament.

It lies opposite of the bodies of 5th, 6th and 7th thoracic vertebra STRUCTURESSTRUCTURES OFOF THETHE ROOTROOT

Principal Bronchus on the left side. Eparterial and Hyparterial on the right side. One pulmonary artery . Two pulmonary veins - Superior Inferior Bronchial arteries One on right side Two on left side BronchialBronchial veinsveins AnteriorAnterior andand posteriorposterior pulmonarypulmonary plexusplexus ofof nerves.nerves. LymphaticsLymphatics BronchopulmonaryBronchopulmonary LymphnodesLymphnodes AreolarAreolar tissue.tissue. ARRANGEMENTARRANGEMENT OFOF STRUCTURESSTRUCTURES ININ THETHE ROOTROOT BEFORE BACKWARDS

1.1. SuperiorSuperior pulmonarypulmonary vein.vein.

2.2. PulmonaryPulmonary artery.artery.

3.3. Bronchus.Bronchus. ARRANGEMENTARRANGEMENT OFOF STRUCTURESSTRUCTURES ININ THETHE ROOTROOT

ABOVE DOWNWARDS

A. Right Side

1. Eparterial Bronchus. 2. Pulmonary Artery. 3. Hyparterial Bronchus. 4. Inferior Pulmonary Vein. . ARRANGEMENTARRANGEMENT OFOF STRUCTURESSTRUCTURES ININ THETHE ROOTROOT

ABOVEABOVE DOWNWARDSDOWNWARDS

B. Left Side

1. Pulmonary artery.

2. Bronchus.

3. Inferior pulmonary vein FISSURESFISSURES ANDAND LOBESLOBES OFOF LUNGLUNGSS OBLIQUEOBLIQUE FISSUREFISSURE

ItIt beginsbegins posteriorlyposteriorly atat thethe levellevel ofof 5th5th thoracicthoracic vertebra.vertebra.

PassesPasses anteroantero--inferiorlyinferiorly inin aa spiralspiral coursecourse toto meetmeet thethe inferiorinferior marginmargin closeclose toto 6th6th costochondralcostochondral junction.junction. HORIZONTALHORIZONTAL FISSUREFISSURE

ItIt extendsextends fromfrom anterioranterior marginmargin atat thethe levellevel ofof 4th4th costalcostal cartilage.cartilage.

RunsRuns horizontallyhorizontally backwardsbackwards toto meetmeet thethe obliqueoblique fissurefissure inin thethe midmid--axillaryaxillary line.line.

PulmonaryPulmonary pleurapleura extendsextends intointo thethe fissuresfissures ofof thethe lungslungs soso thatthat thethe lobeslobes cancan movemove onon eacheach otherother duringduring respiration.respiration.

BRONCHOPULMONARYBRONCHOPULMONARY SEGMENTSSEGMENTS

TheseThese areare wellwell defineddefined areasareas ofof thethe lungs,lungs, eacheach ofof whichwhich isis aeratedaerated byby aa segmentalsegmental // tertiarytertiary bronchus.bronchus.

Trachea

Right and Left Principal Bronchus

Lobar Bronchi(Secondary)[2L,3R]

Segmental Bronchi(Tertiary)[8L,10R]

Terminal Bronchioles(25000 in no.)

Respiratory Bronchioles

Alveolar ducts ACINUS Alveolar sacs

Alveoli

TheThe ultimateultimate pulmonarypulmonary unitunit fromfrom respiratoryrespiratory brochiolebrochiole toto alveolialveoli isis calledcalled AcinusAcinus..

ThereThere areare aboutabout 2828 ordersorders ofof divisiondivision ofof tracheotracheo--bronchialbronchial tree.tree.

TotalTotal no.no. ofof alveolialveoli hashas beenbeen estimatedestimated toto bebe betweenbetween 200200 -- 600600 million,million, withwith aa totaltotal surfacesurface areaarea ofof 4040 -- 8080 metermeter square.square.

BRONCHOPULMONARYBRONCHOPULMONARY SEGMENTSSEGMENTS

RightRight mainmain bronchusbronchus LeftLeft mainmain bronchusbronchus

1.1. ShorterShorter 1.1. LongerLonger

2.2. Wider.Wider. 2.2. Narrower.Narrower.

3.3. MoreMore inin lineline withwith 3.3. MoreMore obliqueoblique thanthan trachea.trachea. thethe right.right. BRONCHOPULMONARYBRONCHOPULMONARY SEGMENTSSEGMENTS

Right Main Bronchus

Right upper lobe Bronchus Right Middle lobe Bronchus Right Lower Lobe Bronchus

Segmental Bronchi Segmental Bronchi Segmental Bronchi

Apical Apical Medial Anterior Anterior Lateral Posterior Posterior Medial and Lateral BRONCHOPULMONARYBRONCHOPULMONARY SEGMENTSSEGMENTS

Left Main Bronchus

Left upper lobe Bronchus Left lower lobe bronchus

Upper Branch Lower Branch Segmental Bronchi

Apical Anterior Superior Lingular Anterior Apico-posterior Inferior Lingular Posterior Lateral

TheseThese segmentssegments areare pyramidalpyramidal inin shapeshape withwith apexapex towardstowards thethe rootroot ofof lung.lung.

EachEach segmentsegment isis anan independentindependent respiratoryrespiratory unit.unit.

EachEach segmentsegment hashas itsits ownown separateseparate artery(branchesartery(branches ofof pulmonarypulmonary artery).artery).

PulmonaryPulmonary VeinsVeins runrun inin interinter--segmentalsegmental planesplanes betweenbetween adjoiningadjoining segments.segments.

ThusThus aa bronchopulmonarybronchopulmonary segmentsegment isis notnot aa bronchovascularbronchovascular segmentsegment asas itit doesdoes notnot havehave itsits ownown veinvein..

CLINICALCLINICAL SIGNIFICANCESIGNIFICANCE

SegmentalSegmental resectionresection withwith minimalminimal destructiondestruction toto thethe surroundingsurrounding lunglung tissue.tissue.

ToTo visualizevisualize thethe interiorinterior ofof aa bronchibronchi throughthrough aa bronchoscopebronchoscope whenwhen diseasesdiseases processprocess isis limitedlimited inin aa segment.segment. HISTOPATHOLOGYHISTOPATHOLOGY OFOF ALVEOLIALVEOLI ALVEOLARALVEOLAR WALLWALL

1. Alveolar epithelial cells- Type I pneumocytes Type II pneumocytes 2. Basement Membrane 3. Interstitial Space- Collagen Elastin Unmyelinated Nerves Macrophages 4. Capillary Basement Membrane 5. Capillary Endothelial Cells. . TypeType II PneumocytePneumocyte

Pavement epithelial cells of alveoli . Less in no. than type II. More surface area(flattened) Contain pinocytic vesicles. Specialized for diffusion of gases. TypeType IIII PneumocytesPneumocytes

More numerous than type I. Cuboidal in shape. Rich in mitochondria, ER and vacuoles containing osmiophillic lamellar bodies. Type I are precursors of type II. ENDOTHELIALENDOTHELIAL CELLSCELLS

Most numerous . Presence of pinocytic vacuoles that meet the luminal surface to form caveolae. Walls of caveolae has, ACE. Source of NO, natural pulmonary vasodilator. ALVEOLARALVEOLAR MACROPHAGESMACROPHAGES

PrimaryPrimary defencedefence mechanism.mechanism.

TakesTakes partpart inin inflammatoryinflammatory andand immunologicalimmunological reactionsreactions.

ActivatesActivates lysosomeslysosomes ,, proteases,complementproteases,complement ,, thromboplastinthromboplastin,, cytokinescytokines -- IFIF--αα,, TNFTNF-- αα,, ILIL--1,1, ILIL--8.8. SURFACTANTSURFACTANT

Lines the inner layer of alveolar epithelium.

Synthesized by SER of type II pneumocytes.

Function – 1. To reduce the surface tension of alveoli mainly during expiration, thus reduces the work of lung inflation. 2. Waterproofing.

Surfactant synthesis starts after 26 weeks of fetal life. Therefore premature infants,with insufficient surfactant suffer from HMD. AllAll thethe bestbest……