Baca BTKV - Dr Suhardi - 28-8-2014

ANATOMY OF THORAXFingga Prahasti Nasution

Vany Netza PutriM. Rizky FachriFika AriskaMaulizaMuhammad RidhoFachrul Razi

Aperture Thoracis Superior :• vertebra thoracalis 1.• Costa 1• Incisura jugularis sterni

Apertura Thoracis InferiorVertebra ThoracalisCosta 9-12Articulatio Xyphysternalis

There are 3: External intercostal muscles – articulates downward and laterally Internal intercostal muscles – articulates perpendicular to external intercostals. Innermost intercostal muscles – fairly trivial.

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Their job is to move the ribs as well as stiffen the chest wall improving efficiency of breathing movements. Just below each rib in the Costal groove, starting from the top, there is the intercostal vein, artery and then the nerve (VAN).

Head of rib is on posterior, then neck and angle.Costal cartilage is anterior.

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Name the structures with which a rib articulates. Posteriorly the ribs articulate with the thoracic vertebra. (T1-T12)Anteriorly Rib 1 has costal cartilage attached to manubrium. Rib 2 has costal cartilage attached to the manubriosternal joint. Ribs 3 – 6 have costal cartilage attached to body of sternum. Rib 7 has costal cartilage attached to xiphisternal joint. Ribs 8 – 10 have costal cartilage attached to that of above rib. Ribs 11 & 12 do not join to anything.

All the joints between the costal cartilages and the sternum are smooth synovial joints. Ribs 1-7 are True ribs Ribs 8-10 are False ribs Ribs 11&12 are Floating ribs

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Vertebrae articulate with each other by thin intervertebral discs between them (which also limits movement)

The disk is made of cartilage. It is therefore a synovial joint. Each disc has an outer fibrous ring consisting of fibrocatilage called annulus

fibrosus and an inner soft, pulpy, highly elastic substance called the nucleus pulposus.

The discs form strong joints, permit various movements of the vertebral column and absorb vertical shock. Under compression, they flatten, broaden and bulge from their intervertebral spaces.

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Lungs, Pleura and Diaphragm

Contents of an intercostal space.

Intercostal space contains: External intercostal muscles Internal intercostal muscles Innermost intercostal muscles Intercostal Vein (in costal groove) Intercostal Artery (in costal groove) Intercostal Nerve (in costal groove) Collateral branches

The pleura is a layer of flattened cells supported by connective tissue that lines each pleural cavity and covers the exterior of the lungs.

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Layer of the pleura.

Pleura consist of 2 layers:Visceral Pleura: this covers the surface of the lungs and is the innermost layer.

Parietal Pleura: this lines the innermost surface of the chest wall and is in contact with the ribs and intercostal muscles. It is the outermost layer.

These 2 layers are separated by the pleural cavity which contains serous fluid produced by the cells in the pleura. This helps the lungs glide as they expand and collapse.

Extent of the lungs.The lungs are conical in shape:

The apex (top) of the lungs reach as high as 3-4 cm above the first costal cartilage, in the base of the neck.

The base (bottom) of the lungs is concave and rests on the diaphragm.Extent of the pleura

.During quiet breathing…

o The inferior margin of the lungs comes down to as far as about rib VI in the

midclavicular line (middle of clavicle) rib VIII in the midaxillary line (runs down side of body) and reaches the vertebral column at TX.

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o The inferior margin of the pleural cavity comes down as far as rib VIII on

the midclavicular line, rib X on the midaxillary line, and reaches the vertebral column at TXII.

o The space between the two margins is the costodiaphragmatic recess.

The right lung:o Has 3 lobes, the inferior lobe, the superior lobe and the middle lobe.

o Has 2 fissures, the oblique fissure, separating the inferior lobe from the

superior and middle lobes; and the horizontal fissure separating the superior lobe from the middle lobe.

o On its mediastinal surface in contact with the heart, inferior vena cava,

superior vena cava, azygos vein oesophagus.o Is larger than the left lung.

The left lung:o Has only 2 lobes, the inferior lobe and the superior lobe.

o Has 1 fissure, the oblique fissure, that separates the superior and inferior

lobes. o On its mediastinal surface is in contact with the heart, aortic arch, thoracic

aorta, and oesophagus. It contains a notch where the heart projects into the pleural cavity from the middle mediastinum.

The term “pulmonary circulation”.o Right atrium Pulmonary Artery Lung capillaries Pulmonary Vein

Left Atrium.o Blood is oxygenated in the lungs.

o Resistance is an eighth of the systemic circulation and blood pressure is only

25/10mmHg.

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The structural basis for breathing, including the differences between light, deep and forced breathing.

Breathing is controlled by the nervous system and produced by the skeletal muscle.

Lungs ventilate the air sacs – the site of gas exchange. Movements of both the diaphragm and the ribs cause an increase of the

thoracic cavity capacityo The muscles in the wall cause expansion of the pleural cavity.

o The elastic lungs expand with the pleural cavity.

o Air is sucked down the trachea and bronchi into the lungs.

The Ribs move up forward and upward with a bucket-handle like action. This increases the anteroposterior, as well as the transverse dimensions of the thoracic cavity.

The Diaphragm is the main inspiratory muscle. When it contracts the vertical dimension of the thoracic cavity is greatly increased. This also pushes the contents of the abdominal cavity down and out.

Inspiration is caused by the increase in thoracic cavity capacity which results in a reduction in the intrapleural pressure. This causes expansion of the lung and therefore entry of the air through the respiratory passages.

Quiet inspiration uses only the diaphragm. Forced inspiration uses both the diaphragm and intercostal muscles.

Expiration is caused by the elastic recoil in the tissue around the lungs and rib cage. Quiet expiration uses only the diaphragm. Forced expiration uses both the diaphragm and abdominal muscles.

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Superior Mediastinum and Great Vessels

The mediastinum is the partition that separates the two pleural cavities. It extends from the superior thoracic aperture to the diaphragm vertically and from the sternum to the vertebral column laterally. At the level of TV, it splits into:

Superior mediastinum Inferior mediastinum which

itself is split into anterior, middle and posterior mediastinum

Position and relations of the aortic arch and descending aorta. The ascending aorta leaves the left ventricle and is continuous with the aortic arch.

Two branches come off the ascending aorta giving rise to the left & right coronary arteries.

Aortic arch is behind sternal angle. It arches posteriorly and to the left over the left bronchi of the tracheal bifurcation. (Vertebral level TIV/TV.

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Middle

Ant

Post

Inferior

Superior

It then goes down behind the left main bronchus to become the descending aorta.

At top of the aortic arch 3 branches come out:

Brachiocephalic trunk – this goes off to the right side of the body and almost immediately splits into the right subclavian artery which goes to the right arm, and the right common carotid artery which goes up to the head.

Left common carotid artery – this goes up to supply the left side of the face and head. It arises slightly posterior (behind) the brachiocephalic trunk and extends along the left side of the trachea.

Left subclavian artery – this goes on to supply the left arm. It arises slightly posterior and just left of the left common carotid artery.

(a) Blood reaches head and neck via the left and right common carotid arteries. These then split into external and internal common carotid high in the neck.

(b) Blood reaches lungs via the pulmonary arteries. These arise from the pulmonary trunk (still contained within the pericardial sac) which arises from the right ventricle. Just inferior and to the left of the sternal angle, the pulmonary trunk splits into left & right pulmonary arteries. Once blood has been oxygenised, it passes into the pulmonary veins which drain directly into the left atrium.

(c) Blood reaches the abdominal and thoracic cavities from a number of different arteries.

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Organisation of Nerves in the Thorax

Pericardium in the cadaver and describe its organisation.

The pericardium is a fibrous sac that surrounds the heart and the roots of the great vessels. It consists of two parts:

Fibrous pericardium - This is a cone-shaped bag containing the serous pericardium, heart and entrance of associated vessels (The phrenic nerve also innervates this layer), and its apex is continuous with the adventitia of the great vessels.

Serous pericardium – this itself is split up into 2 layers:

o Parietal layer – which lines the inner surface of the fibrous pericardium,

i.e. the outermost layer. Around the roots of the great vessels it is continuous with the visceral layer.

o Visceral layer – this is also known as the epicardium. It forms the outer

covering of the heart.

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o

The Right atrium is on the right border of the heart on the anterior surface. Blood enters the right atrium from:

superior vena cava inferior vena cava coronary sinus

Its walls are covered in pectinate muscles which fan out like the teeth of a comb. Just posterior to it is the interatrial septum (the left atrium lies posterior to the right). There is a depression in the interatrial septum known as the fossa ovalis and around it the

limbus fossa ovalis. This is very important during foetal life as it was the foramen ovale, a hole between the left and right atria so blood can bypass the non-functioning lungs before birth.The right ventricle is on the diaphragmatic border of the heart and also faces anteriorly, blood moving from right atrium to right ventricle therefore moves in a horizontal direction. Its outflow is the pulmonary trunk. There are 3 papillary muscles in the right ventricle:

Anterior papillary muscle is the largest. Posterior papillary muscle arises from posterior wall Septal papillary muscle which arises from the septum.

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The left atrium receives oxygenated blood from the 4 pulmonary veins. It forms most of the posterior (back) surface and is not seen at all anteriorly. The valve of the foramen ovale is also seen in the interatrial septum. Its exit point is the mitral valve.

The Left ventricle lies slightly anterior and superior to the left atrium. It is conical in shape and is the longest and most muscular of the chambers of the heart. (I.e. it has the thickest layer of myocardium). It, like the right ventricle has traberculae carneae and papillary muscles with attached chordae tendinae. There are only 2 papillary muscles; posterior and anterior.

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There are 2 main coronary arteries each arising from one of the aortic sinuses (left and right) each giving rise to its corresponding coronary artery: The right coronary artery emerges from the right aortic sinus and descends

down the right atrium round to the apex of the heart branching as it does so. It supplies the right atrium, right ventricle, sino-atrial node and atrioventricular node.

The left coronary artery emerges from the left aortic sinus and passes down posterior (behind) to the pulmonary trunk. As it emerges it splits into two:o Anterior descending branch which descends anteriorly round toward

the apex of the heart.o Circumflex branch which travels round the left side of the heart and

descends on the posterior left side of the heart.The left coronary artery supplies the left atrium, left ventricle and most of the interventricular septum.

There are 2 variations in the distribution patterns of the coronary arteries:- Right coronary dominance : is the most common and it is where the right

coronary artery supplies most of the posterior wall and the left coronary arteries are relatively small.

- Left coronary dominance : is less common and is where the circumflex branch supplies the majority of the posterior wall and left ventricle.

There are 4 main cardiac veins that drain into the coronary sinus which itself drains into the right atrium. Great cardiac vein : begins at the apex of the heart and runs up the anterior

(front) wall along the atrioventricular sulcus, when it reaches the top it goes round the end following the path of the circumflex artery and enlarges at the posterior end to form coronary sinus.

Middle cardiac vein : also begins at the apex but runs up the posterior side in the atrioventricular sulcus.

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Small cardiac vein : begins in the lower anterior (front) sector of the anterior sulcus. It travels round the back of the right atrium where it finishes in the coronary sinus.

Posterior cardiac vein : runs up the posterior surface of the left atrium.

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References

Faiz, O., Blackburn, S., Moffat, D. 2011. At a glance anatomy 3rd edition. Jakarta: EGC

Guyton, Hall. 2008. Medical of Physiology. USA: Mc Graw Hill.

Moore, K. L. and A. F. Dalley. 1999. Clinically Oriented Anatomy, 4th Ed. Lippincott,Williams & Wilkins, Baltimore.

Wascheke,F.P.J. 2012. Atlas Anatomi Sobotta 23rd edition. Jakarta: EGC

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