Pleura & Pleural Cavities

8/2/2019 Pleura & Pleural Cavities

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Developmental..

??

Where did it come from


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The pleural cavities

The thoracic cavity, the spaceenclosed by the thoracic walls,has three compartments

Two lateral compartments arethe pulmonary cavities that

contain the lungs and pleurae(lining membranes) & centralcompartment the

It is important to note that thelungs are not within the pleuralcavity.

The cavity is the spacebetween the visceral and

parietal layers of pleura. The lungs are surrounded by

the pleurae, a serousmembrane which folds backupon itself to form a two-layered, membrane structure.

The thin space between thetwo pleural layers is known asthe pleural space


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Pleural

A thin serous membraneinvaginated by the lung.

Intimately related to lung

Continuous over the rootof the lung with parietalpleura.

The Fist in glove model


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The pleura..

The visceral pleura(pulmonary pleura)

covers the lungs and

is adherent to all itssurfaces, including thesurfaces within thehorizontal and obliquefissures, it cannot bedissected from thelungs.

The parietal pleura

lines the pulmonarycavities, adhering to

the thoracic wall, themediastinum, and thediaphragm.


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The pleura

The parietal pleura consists Costal part (pleura)

covers the internal surfaces of thethoracic wall (sternum, ribs, costalcartilages, intercostal muscles andmembranes, and side of thoracicvertebrae)

separated from the wall byendothoracic fascia.

Mediastinal part (pleura) covers the lateral aspects of the

mediastinum (the centralcompartment of the thoraciccavity).

Diaphragmatic part (pleura) covers the superior or thoracic

surface of the diaphragm on eachside of the mediastinum.

Cervical pleura extends through the superior

thoracic aperture into the root ofthe neck

2-3 cm superior to the level of themedial third of the clavicle at thelevel of the neck of the 1st rib,

forming a cup-shaped dome overthe apex of the lung.

reinforced by a fibrous extension

of the endothoracic fascia, thesuprapleural membrane (Sibsonfascia) spanning between the 1strib and C7 vertebra.


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The pleura

Parietal pleura

Cervical

Costal

Diaphragmatic

Mediastinal

Visceral pleura


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The recesses

Costodiaphragmatic recesses

diaphragmatic pleura incontact with the lowermostpart of the costal pleura.

The potential space pleura

lined surround the upward convexity

of the diaphragm inside thethoracic wall

The costomediastinal recesses

the smaller pleural recessesposterior to the sternum w

costal pleura in contact withthe mediastinal pleura.

the left recess is potentiallylarger (less occupied) becauseof the cardiac notch in the leftlung.

The inferior borders of thelungs move farther into the

pleural recesses during deepinspiration and retreat fromthem during expiration.


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Fist invaginatingmodel -


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Pulmonary ligament.

Inferior to the root ofthe lung, this continuity

between parietal andvisceral pleura formsthe pulmonaryligament extendingbetween the lung and

the mediastinum.


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Pleural reflection

The cervical pleurae and apices

through the superiorthoracic aperture into theroot of the neck & posteriorto the clavicles.

The anterior borders of the lungs

anterior line of reflection ofthe parietal pleura betweenthe 2nd and 4th costalcartilages.

left pleural reflection

laterally & inferiorly at thecardiac notch to reach 6thcostal cartilage.

The anterior border of theleft lung

deeply indented by itscardiac notch.


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reflections

On the right pleural

reflection continuesinferiorly from the 4th to the6th costal cartilage,

paralleled anterior borderof the right lung.

Both pleural reflectionspass laterally and reach

the midclavicular line at 8thcostal cartilage,

10th rib at the midaxillaryline,

12th rib at the scapularline, to T12 vertebra.

Parietal pleura extendsapproximately two ribsinferior to the lung.


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Vasculature..

The veins fromthe parietal pleura

join the systemicveins in adjacentparts of thethoracic wall.

The veins fromthe visceral pleuradrain into thepulmonary veins.

Lymphatics-


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Vasculature..Lympahtics

The superficial(subpleural) lymphaticplexus drains lymph fromthe visceral pleura.

Lymph from the parietalpleura drains into thelymph nodes of thethoracic wall

(intercostal, parasternal,mediastinal, and phrenic).

A few lymphatic vesselsfrom the cervical pleuradrain into the axillarylymph nodes.


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Vasculature.. nerves

Visceralpleura- pleura nerve supply derive from the pulmonary plexuses located

anterior and (mainly) posterior to the roots of the lungs

These nerve networks contain parasympathetic fibers from the

vagus nerves (CN X) and sympathetic fibers from the

sympathetic trunks.

Parietal

Somatic intercostals nerves&phrenic


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Functional anatomy

The pleural cavity, with itsassociated pleurae,

aids optimal functioning of thelungs during respiration.

The pleurae are coated with

lubricating pleural fluid whichallows the pleurae to slideeffortlessly against each otherduring ventilation.

Surface tension of the pleuralfluid also leads to closeapposition of the lung surfaceswith the chest wall.

This physical relationship

allows for optimal inflation ofthe alveoli during respiration.

Movements of the chest wall,particularly during heavybreathing, are coupled tomovements of the lungs since

the closely opposed chest walltransmits pressures to thevisceral pleural surface and,hence, to the lung itself.


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Pleural fluid

Pleural fluid is a serous fluidproduced by the pleurae.

A normal 70 kg human hasapproximately 12-15 mL of pleuralfluid.

In normal pleurae, most fluid isproduced by the parietalcirculation (intercostal arteries) viabulk flow and reabsorbed by thelymphatic system.

pleural fluid is continuouslyproduced and reabsorbed.

The rate of reabsorption mayincrease up to 40x beforesignificant amounts of fluidaccumulate within the pleuralspace.

In humans, there is no anatomical

connection between the left andright pleural cavities, so in casesof pneumothorax, the otherhemithorax will still functionnormally.


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Functional anatomy..

Physiological Movements of membranes-

serous, smoothen

Injury to Pleurae The visceral pleura is insensitive

to pain innervation is autonomic (motorand visceral afferent).

The autonomic nerves reach thevisceral pleura in company withthe bronchial vessels. The visceralpleura receives no nerves ofgeneral sensation.

The parietal pleura is sensitive topain, particularly the costal pleura,because it is richly supplied bybranches of the somaticintercostal and phrenic nerves.

Irritation of the parietal pleuraproduces local pain andreferred pain to the areassharing innervation by thesame segments of the spinalcord.

Irritation of the costal andperipheral parts of thediaphragmatic pleura - localpain and referred pain alongthe intercostal nerves to thethoracic and abdominal walls.

Irritation of the mediastinaland central diaphragmaticareas of the parietal pleurapain - referred to the root ofthe neck and over theshoulder


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Functional, Injury ..

Cervical pleura Prone to stab injuries & surgeons knife

Niddle at 4th&5th ICS by pass the pleural to pericardium.

Pleural below 12th rib in the medial may be opened in the loin

(adrenal/renal surgery)

Pleural effusion

Empyema thoracis

Decortication

Tumours (mesotheliomas)

Pleura & Pleural Cavities

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