The heart and lungs

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Pericardium The mediastinum

contains the pericardium, heart, and roots of great vessles (ascending aorta, pulmonary trunk, and SVC).

It’s a double walled fibrous sac that enclose the heart and the root of great vessels.

Composed of two parts:

A. Tough outer fibrous pericardium

B. The serous pericardium ( parietal fused with and visceral) forming the pericardial cavity containing serous fluid to allow free heart movement.

The heart It’s a muscular pump to propel blood to all parts of

the body. The right side receive poorly oxygenated blood ( venous blood) from the body through the SVC and IVC and pump it to the lung via the pulmonary trunk for oxygenation.

The left side receive well oxygenated blood (arterial) blood from the lungs through the pulmonary veins and pump it onto aorta for distribution to the body.

It has 4 champers right and left atria, and right and left ventricles .

The atria are receiving champers that pump blood into ventricles.

Surface anatomy The heart and great

vessels are approximately in the middle of the thorax surrounded laterally and posteriorly by the lungs and bound anteriorly by the sternum and the central part of the thoracic cage.

The apex located at the 5th intercostal space.

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Superior Mediatinum Superior to the transverse thoracic plane

passing though the sternal angle and the junction of (IV disc) of vertebrae T4 and T5.

Main content Thymus gland (lymphoid organ) Great vessels related to the heart

( brachiocephalic vein and SVC) Arch of the aorta and its major branches

(brachiocephalic trunk, left common carotid and left subclavian)

Nerves Trachea Esophagus

Surface anatomy

The heart and great vessels are approximately in the middle of the thorax surrounded laterally and posteriorly by the lungs and bound anteriorly by the sternum and the central part of the thoracic cage.

The apex located at the 5th intercostal space.

Surface Anatomy of heartApex: L.5th interc. Space, 9cm

from midlineBorders of the heart:Right border:Point at upper bor. Of R. 3rd

C.C.,1.5cm from Sternal margin

To point on R. 6th C.C., 2cm from sternal bor.

Line is convex to R. lat. Wall of R. atriumMarks S.V.C. & I.V.C.Lower Border:A point from R. 6th C.C., 2cm

from sternal bor.To apex (L.5th interc.

Space,9cm from midline)Its R. 2/3 R. vent. & L. 1/3

L. vent.

The thorax

The cylindrical thorax consists of:

a wall; two pleural cavities; the lungs; the mediastinum. The thorax houses the heart

and lungs In addition, the thoracic wall

protects the heart and lungs and provides support for the upper limbs.

Pleurae Each lung is

enclosed in pleural sac that consist of 2 membrane:

Visceral invest the lungs surface it can not be dissected

Parietal that lines the pulmonary cavities.

The pleural cavity is the space between the 2 layers containing a serous fluid which lubricate the pleural surface and allow layers to slide smoothly over each other. (layers of water between 2 glass plates).

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mediastinum The mediastinum is a thick midline

partition that extends from the sternum anteriorly to the thoracic vertebrae posteriorly, and from the superior thoracic aperture to the inferior thoracic aperture.

A horizontal plane passing through the sternal angle and the intervertebral disc between vertebrae TIV and TV separates the mediastinum into superior and inferior parts.

The inferior part is further subdivided by the pericardium, which encloses the pericardial cavity surrounding the heart.

The pericardium and heart constitute the middle mediastinum.

The anterior mediastinum lies between the sternum and the pericardium;

the posterior mediastinum lies between the pericardium and thoracic vertebrae.

Mediastinum

is a broad central partition that separates the two laterally placed pleural cavities

It extends: from the sternum to

the bodies of the vertebrae; and

from the superior thoracic aperture to the diaphragm

The mediastinum contains the thymus gland, the pericardial sac, the heart, the trachea, and the major arteries and veins.

Additionally, the mediastinum serves as a passageway for structures such as the esophagus, thoracic duct, and various components of the nervous system as they traverse the thorax on their way to the abdomen

mediastinum

A transverse plane extending from the sternal angle (the junction between the manubrium and the body of the sternum) to the intervertebral disc between vertebrae TIV and TV separates the mediastinum into:

superior mediastinum; and inferior mediastinum, which is

further partitioned into the anterior, middle, and posterior

mediastinum by the pericardial sac. The area anterior to the pericardial sac

and posterior to the body of the sternum is the anterior mediastinum.

The region posterior to the pericardial sac and the diaphragm and anterior to the bodies of the vertebrae is the posterior mediastinum.

The area in the middle, which includes the pericardial sac and its contents, is the middle mediastinum

pleural cavity

Each pleural cavity is completely lined by a mesothelial membrane called the pleura.

Each lung remains attached to the mediastinum by a root formed by the airway, pulmonary blood vessels, lymphatic tissues, and nerves.

The pleura lining the walls of the cavity is the parietal pleura, whereas that reflected from the mediastinum at the roots and onto the surfaces of the lungs is the visceral pleura.

The lung does not completely fill the potential space of the pleural cavity, resulting in recesses, which do not contain lung and are important for accommodating changes in lung volume during breathing.

The costodiaphragmatic recess, which is the largest and clinically most important recess, lies inferiorly between the thoracic wall and diaphragm.

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.

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.

The right lung 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.

left lung

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

Right lung Right lung The right lung has three

lobes and two fissures These invaginations form

the fissures: the oblique fissure the horizontal fissure

4) Structures behind (post.) the lung:1. Esophagus2. Azygos V. (behind esophagus)3. Th. V. & parts of ribs4. R. Symp. Tr. & Greater splanchnic

N.

Azygos Vein