Kaan Yücel M.D., Ph.D.

Salvador Dali - Anthropomorphic Chest of Drawers, 1936

THORACIC WALL, MEDIASTINUM

CARDIOVASCULAR SYSTEM

22. 3. 2013

1. THORAX

the part between the neck and the abdomen

Chest X-ray

1.1. REGIONS/T ERMS

Thoracic cavitycavity between neck and abdomen protected by the thoracic wall.

Thoracic wallbounds the thoracic cavity. formed by the skin, bones, fasciae, and muscles.

Thoracic cagebony portion of the thoracic wallthoracic skeleton

1.2. SURFACES OF THE THORAX

Posterior surface 12 thoracic vertebræ & posterior parts of the ribs

Anterior surfacesternum & costal cartilages

Lateral surfaces ribs, separated by the intercostal spaces

STERNUM & COSTAL CARTILAGES anteriorly12 THORACIC VERTEBRAE & POST. RIBS posteriorlyRIBS & INTERCOSTAL SPACES laterally

1.3. BOUNDARIES OF THE THORAXSuperior• Jugular notch• Sternoclavicular joint• Superior border of clavicle• Acromion• Spinous processes of C7

Inferior • Xiphoid process• Costal arch• 12th and 11th ribs• Vertebra T12

1.4. CONTENTS OF THE THORAX

Organs of the cardiovascular, respiratory, digestive, reproductive, immune, and nervous systems

2. THORACIC WALL

• thoracic cage (skeleton) • muscles between the ribs • skin • subcutaneous tissue• muscles, and fascia covering its anterolateral aspect.

The mammary glands of the breasts lie within the subcutaneous tissue of the thoracic wall.

2.1. FUNCTIONS OF THE THORACIC WALL1) Protects vital thoracic and abdominal organs2) Resists the negative (sub-atmospheric) internal pressures

generated by the elastic recoil of the lungs and inspiratory movements.

3) Provides attachment for and support the weight of the upper limbs.

4) Provides the origins of many of the muscles that move and maintain the position of the upper limbs relative to the trunk.

5) Provides attachments for muscles of the abdomen, neck, back, and respiration.

3. SKELETON OF THE THORACIC WALL1) 12 pairs of ribs and associated costal cartilages2) 12 thoracic vertebrae and the intervertebral (IV) discs

interposed between them3) Sternum

4. THORACIC APERTURES‘Thoracic inlet’

‘Thoracic outlet’

4.1. Superior thoracic aperture

“doorway” between the thoracic cavity and the neck and upper limbbounded: Posteriorly vertebra T1Laterally 1st pair of ribs and their costal cartilagesAnteriorly superior border of the manubrium

Trachea Esophagus nerves, and vessels that supply and drain the head, neck, and upper limbs.

4.2. Inferior thoracic aperture

By closing the inferior thoracic aperture, the diaphragm separates the thoracic and abdominal cavities almost completely.

bounded:Posteriorly 12th thoracic vertebraPosterolaterally 11th and 12th pairs of ribs Anterolaterally joined costal cartilages of ribs 7-10 costal margins Anteriorly xiphisternal joint

5. JOINTS OF THE THORACIC WALL1. Costotransverse jointsbetween tubercle of a rib & transverse process of its own vertebra

2. Sternocostal jointbetween the sternum and costal cartilages

3. Costachondralis jointbetween the rib and costal cartilage

4. Intercondral jointsSynovial joints between the costal cartilages of 6th and 7th, 7th and 8th,& 8th and 9th ribs. 5. Sternal Jointsbetween the manubrium, body, xiphoid process of the sternum.

6. MUSCLES OF THE THORACIC WALL

Serratus posterior Levator costarum Intercostal muscles(External, internal and innermost) Subcostal Transverse thoracic

6. MUSCLES OF THE THORACIC WALL

external intercostal muscles most superficialinternal intercostal musclesbetween external & innermost muscles

intercostal musclesthree flat muscles found in each intercostal space

6. MUSCLES OF THE THORACIC WALL

pass obliquely anteroinferiorly

external intercostal musclesextend from the inferior margins of the ribs above

to the superior margins of the ribs below

6. MUSCLES OF THE THORACIC WALL

internal intercostal muscles

most active during expirationbetween most inferior lateral edge of costal grooves of the ribs above, to the superior margins of ribs below

in the opposite direction to those of the external intercostal muscles

obliquely posteroinferiorly

Attachment to interosseus parts move down during expiration!

6. MUSCLES OF THE THORACIC WALL

same orientation as the internal intercostals

innermost intercostal musclesleast distinct of the intercostal muscles

neurovascular bundles (V.A.N.) in the costal grooves in a plane between innermost & internal intercostal muscles.

6. MUSCLES OF THE THORACIC WALL

transversus thoracis muscleson the deep surface of the anterior thoracic wall & @ same plane as innermost intercostals

lie deep to the internal thoracic vessels secure these vessels to the wall.

6. MUSCLES OF THE THORACIC WALL

Fibers parallel the course of the internal intercostal muscles. Extend from the angle of the ribs

to more medial positions on the ribs below.

subcostales @ same plane as innermost intercostals

6.1. Accessory muscles of respiration

upper accessory muscles assist with inspiration.

upper chest, and abdominal muscles assist with expiration.

6.1. Accessory muscles of respiration Scalene muscles elevate, fix & expanding the upper chest during inspiration.

Sternocleidomasteoid muscles raise the sternum expand the chest’s A-P & longitudinal dimensions.

6.1. Accessory muscles of respiration Axioappendicular muscles act primarily on the upper limbs.

pectoralis major Attachment to first seven costal cartilages

pectoralis minor Attachment to anterior surfaces of the 3rd-5th ribs

inferior part of the serratus anteriorAttachment to lateral surfaces of upper 8-9 ribs & deep fascia overlying related intercostal spaces

help elevate the ribs to expand the thoracic cavity.

6.1. Accessory muscles of respiration Trapezius raises the thoracic cage.

Attachment to spinous processes of the thoracal vertebrae

6.1. Accessory muscles of respiration Expiration

Abdominal muscles pull the lower chest downdepress the lower limbscompress the abdominal content & exerts pressure on chest.

7. MOVEMENTS OF THE THORACIC WALL

One of the principal functions of the thoracic wall and the diaphragm is to alter the volume of the thorax and thereby move air in and out of the lungs.During breathing, the dimensions of the thorax change in vertical, lateral, and A-P directions.

Diaphragm contracts DepressionDiaphragm relaxes Elevation (during passive expiration)

Elevation &depression of the ribs

Diaphragm conracts; thoracic cavity descends, compressing the abdominal viscera

expiration (back to neutral position)

Lungs produces sub-atmospheric pressure

As a result, the diaphragm ascends, diminishing the vertical dimension.

Vertical dimension

inspiration

Movement of the ribs (primarily 2nd-6th) at the costovertebral joints causes the anterior ends of the ribs to rise

+ Slight elevation in A-P of the sternum.

A-P dimension

intercostal muscles contract

pump-handle movement

Transverse dimensionintercostal muscles contract, raising the middle (lateral-most parts) of the ribs (especially the lower ones)

bucket-handle movement

9. VASCULATURE OF THE THORACIC WALL

Mainly posterior and anterior intercostal arteriespass between adjacent ribs in intercostal

spaces.

9.1. ARTERIES OF THE THORACIC WALLArterial supply to the thoracic wall derives from

Thoracic aorta [posterior intercostal & subcostal arteries]

Subclavian artery [internal thoracic & supreme intercostal arteries]

Axillary artery [superior & lateral thoracic arteries]

course through the thoracic wall between the ribs.

Each intercostal space is supplied by • a large posterior intercostal artery• small pair of anterior intercostal

arteriesException last two intercostal spaces

intercostal arteries

Anterior intercostal arteries (paired)directly or indirectly from internal thoracic artery 1st-6th (from internal thoracic artery) 7th-9th (from musculophrenic-branch of internal thoracic)

Posterior intercostal arteries (large, unpaired) 1st-2nd (from supreme intercostal artery- branch of costocervical trunk) 3rd-11th (from thoracic aorta) Subcostal artery (from thoracic aorta)

internal thoracic artery

•Very first branch of the subclavian artery•Passes vertically through the superior thoracic aperture •Lies posterior to the costal cartilages of the upper 6 ribs •Lies 1 cm lateral to the sternum.

@ level of 6th intercostal space, divides into 2 terminal branches superior epigastric artery & musculophrenic artery

9.2. VEINS OF THE THORACIC WALLMost posterior intercostal veins (4-11) end @ azygos/hemiazygos venous system conveys venous blood to SVC.

1st posterior intercostal veins right & left brachiocephalic veins

2nd & 3rd (sometimes 4th) form superior intercostal vein.

Right superior intercostal vein final tributary of azygos veinLeft superior intercostal vein empties into left brachiocephalic vein.

VeinsArtery V.A.N.Nerve

10. NERVES OF THE THORACIC WALL

12 pairs of intercostal nervesanterior rami of spinal nerves T1 to T11

lie in the intercostal spaces between adjacent ribs.

Anterior ramus of spinal nerve T12 (subcostal nerve) inferior to rib XII.

• Near the angles of the ribs, the nerves pass between internal intercostal & innermost intercostal muscles.

V.A.N.

• Neurovascular bundles sheltered by the inferior margins of the overlying rib.

10.3. DERMATOMES

Through its posterior ramus and the lateral and anterior cutaneous branches of its anterior ramus, most thoracic spinal nerves (T2-T12) supply a strip-like dermatome of the trunk extending from the posterior median line to the anterior median line.

Skin area supplied by a segment of the spinal cord

T2- Sternal angleT4- NippleT6- Xiphoid processT8- Costal archT10-UmbliculusT12-Midpoint between umbilicus and symphysis pubis

11. BREASTS

Mammary glands & associated skin -connective tissues.

modified sweat glands in the superficial fascia anterior to the pectoral muscles and the anterior thoracic wall.

Reproduction, back painAesthetics, and breast cancer

11. BREASTS Mammary glands: Series of ducts and associated secretory lobules.

Form 15 to 20 lactiferous ducts open nipple.

Nipple is surrounded by a circular pigmented area of skin areola (L. small area).

11.1. FEMALE BREASTS

NON-LACTING WOMEN – PREDOMINANT COMPONENT: FATLACTING WOMEN- PREDOMINANT COMPONENT: GLANDULAR TISSUE

The breast rests on a bed extends transversely from lateral border of the sternum mid-axillary line vertically from the 2nd through 6th ribs

Lymphatic drainage of the breast75% (lateral breast quadrants) Axillary lymph nodes

Most of the remaining (medial breast quadrants) parasternal lymph nodes or to the opposite breast

Lymph from inferior quadrants may pass deeply to abdominal lymph nodes.

.

Axillary lymph nodes

Clavicular lymph nodes

Subclavian lypmhatic trunk

Parasternal lymph nodes

Bronchomediastinal lymph trunks

Right or left venous angle

1. MEDIASTINUM(Interpleaural space)

Thoracic cavity is divided into 3 major spaces1) mediastinum 2) right pulmonary cavity3) left pulmonary cavity

central compartment of the thoracic cavity

Looseness of the connective tissue Elasticity of the lungs & parietal pleura on each side of the mediastinum movements of the diaphragm, thoracic wall, & tracheobronchial tree contraction (beating) of the heart pulsations of the great arteries passage of ingested substances through the esophagus

Mediastinum extends fromsuperior thoracic aperture superiorly to diaphragm inferiorly

from sternum & costal cartilagesanteriorly to bodies of thoracic vertebrae posteriorly

transverse thoracic planeSuperior Inferiormediastinum mediastinum

Mediastinumsternal angle

intervertebral disc between T4 - T5

trachea, esophagus, thymus, vagus nerve, phrenic nerve and great vessels such as arch of aorta, brachiocephalic vein

Inferior mediastinum further divided into three parts Anterior mediastinumBetween anterior surface of pericardium & sternumMiddle mediastinumPericardium, heart and beginnings of the great vessels Posterior mediastinumposterior to the pericardium & diaphragm [T5-T12]

thoracic aorta, esophagus

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1.HEART

Trapezoidal in A-P dimensionsTipped-over pyramid in 3-D

crucial organ of the human body

(1)7.3 million

30%

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Right heart (Suction)poorly- oxygenated(venous) blood

from the bodysuperior vena cava & inferior vena cava right atrium right ventricle

pulmonary arteries lungs

Left heart (Pumping)well- oxygenated (arterial) blood

from the lungs pulmonary veins

left atrium left ventricleaorta

the body

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The four chambers of the heartright and left atria & right and

left ventriclesAtrium – plural atria

Receiving chambers

Ventricles

Discharging chambers

cardiac cycle1. Ventricular filling (diastole)2. Ventricular emptying

(systole)Blood pressure120-80 mm/Hg

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The fibrous skeleton of the heart

Keeps the orifices of the AV & semilunar valves patent prevents them from being overly distended by an increased volume of blood.

Provides attachments for the valves & myocardium.

Forms an electrical «insulator»separating impulses of the atria & ventricles they contract independently surrounding and providing passage for the initial part of the AV bundle

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SULCI/GROOVES IN THE HEART coronary sulcus (atrioventricular groove)

between atrium & ventricles

anterior & posterior interventricular (IV) sulci (grooves)

between right and left ventricles

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APEX & BASE OF THE HEARTapex located inferiorly & base located

superiorlyApex projects forward, downward and to the left

Base faces in a posterior direction

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Anterior (sternocostal) surface o mostly of right ventricleo some of the right atrium on the right o some of the left ventricle on the left

Diaphragmatic (inferior) surfaceo formed mainly by the left ventricle o partly by the right ventricleo related to central tendon of diaphragm.

Right pulmonary surface o formed by the right atrium.

Left pulmonary surfaceo left ventricle & a portion of left atrium.

THE FOUR SURFACES OF THE HEART

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2.RIGHT ATRIUM forms the right border of

the heartReceives venous blood from the SVC, IVC, and coronary sinus.

Through the right atrioventricular orifice, discharges the poorly oxygenated blood it has received

into the right ventricle.

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3.RIGHT VENTRICLEforms

largest part of the anterior surface of the hearta small part of the diaphragmatic surfacealmost the entire inferior border of the heart.

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Bulges into the cavity of the right ventricle.

Superiorly and posteriorly, a thin membrane, forms the much smaller membranous part of the IVS.

interventricular septum (IVS)

muscular and membranous partsobliquely placed partition between the right and left ventricles, forming part of the walls of each

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4.LEFT ATRIUM

right and left pulmonary veins enter here. Tubular, muscular left auricle, Its wall trabeculated with pectinate muscles.

forms most of the base of the heart

A semilunar depression in the interatrial septum Floor of the oval fossa

surrounding ridge Valve of the oval fossa

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5.LEFT VENTRICLEforms the apex of the heart, left (pulmonary) surface & border, most of the diaphragmatic surface.

Compared to the right ventricle Walls 2-3 times thicker Trabeculae carneae finer and more numerousCavity longer Anterior & posterior papillary muscles larger

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aortic valve semilunar valvebetween the left ventricle & ascending aortaobliquely placed.

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Guards the left AV orifice.Has two cusps, anterior and posterior.

mitral valvedouble-leaflet mitral valve

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6. SEMILUNAR VALVESSemilunar cusps of the pulmonary valve anterior-right-left

Seminular cusps of the aortic valve posterior-right-left

concave when viewed superiorlyno tendinous cords to support

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7. VASCULATURE OF THE HEART

embedded in fat course across the surface of the heart just deep to the epicardium.

coronary arteries & cardiac veins

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ARTERIAL SUPPLY OF THE HEARTcoronary arteriesfirst branches of the aortasupply the myocardium and epicardium

Anastomoses between the branches of the coronary arteries exist, which enables the development of the collateral circulation.

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8. STIMULATING, CONDUCTING, & REGULATING SYSTEMS OF HEART

1. sinuatrial (SA) node initiates the heartbeat & coordinates contractions of the four heart chambers2.atrioventricular (AV) node

3.bundleshighly specialized conducting fibers for conducting impulses rapidly

to different areas of the heart

o Propagation of the impluseo Simultaneous contraction of the cardiac striated muscle cells

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SINUATRIAL (SA) NODEpacemaker of the heart

@junction of the SVC & right atriumnear to the superior end of the sulcus terminalis

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stimulated by sympathetic division of the autonomic nervous system to accelerate the heart rate

inhibited by parasympathetic division to return to or approach its basal rate.

SINUATRIAL (SA) NODEpacemaker of the heart

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ATRIOVENTRICULAR (AV) NODEa smaller collection of nodal tissue than the

SA nodein the posteroinferior region of the interatrial septumnear the opening of the coronary sinus

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JOURNEY OF THE SIGNALGenerated @ SA node

Passed through the walls of the right atrium

Propageted by the cardiac muscle

Signal passed from SA node to AV node

Distributed to the ventricles through the AV bundle

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BUNDLES

passes from the AV node through the fibrous skeleton of the heart and along the membranous part of the IVS.

@ junction of membranous & muscular parts of the IVSdivides into : right bundle & left bundle.

AV bundlethe only bridge between the atrial and ventricular myocardium

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right and left bundles proceed on each side of the muscular IVS deep to the endocardium then ramify into

subendocardial branches (Purkinje fibers) extend into the walls of the respective ventricles.

BUNDLES

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INNERVATION OF THE HEARTautonomic nervous system,

cardiac plexus Cardiac plexus

posterior to the ascending aorta and bifurcation of the pulmonary trunk

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Parasympathetic supply presynaptic fibers of the vagus nerves

Slows the heart rateReduces the force of the contractionConstricts the coronary arteries saving energy

INNERVATION OF THE HEARTautonomic nervous system,

cardiac plexus

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sympathetic supplypresynaptic fiberscell bodies in the intermediolateral cell columns (IMLs) of the superior 5 or 6 thoracic segments postsynaptic sympathetic fiberscell bodies in the cervical and superior thoracic paravertebral ganglia of the sympathetic trunks.

causes increased heart rateincreased impulse conduction, increased force of contraction, increased blood flow through the coronary vessels increased activity.

INNERVATION OF THE HEART

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11. PERICARDIUM

a closed sac with two layersfibrous pericardium

serous pericardiumparietal layervisceral layer –heart & great vessels.

fibroserous membrane, covers the heart & beginning of its great vessels

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Continuous inferiorly w/ central tendon of the diaphragm Attached anteriorly to the sternum by sternopericardial ligamentsSite of continuity pericardiacophrenic ligament Inner surface lined by parietal layer of the serous pericardium Protects the heart against sudden overfilling.

fibrous pericardiumcontinuous superiorly w/ tunica adventitia of the great vessels & w/pretracheal layer of deep cervical fascia

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contains a thin film of fluid : pericardial fluidenables the heart to move and beat in a frictionless environment.

pericardial cavity potential space between opposing layers of the parietal & visceral layers of serous pericardium

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12. GREAT VESSELS

posterior to the sternoclavicular (SC) joints.

brachiocephalic veins unite to form the SVC.

@ inferior border of the 1st right costal cartilage

shunt blood from the head, neck, & upper limbs right atrium.

RIGHT & LEFT BRACHIOCEPHALIC VEINS formed by the union of internal jugular & subclavian veins

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Returns blood from all structures superior to the diaphragmexcept the lungs

& heart.

Passes inferiorly and ends by entering right atrium of the heart.

SUPERIOR VENA CAVA (SVC)

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begins at the aortic orifice.

only branches coronary arteries, arising from the aortic sinuses.

ASCENDING AORTA

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begins posterior to the 2nd right sternocostal (SC) joint at the level of the sternal angle. ligamentum arteriosum remnant of the fetal ductus arteriosus

root of the left pulmonary artery inferior surface of the arch of the aorta

The usual branches of the arch 1) brachiocephalic trunk2) left common carotid artery3) left subclavian artery.

Arch of the aorta (Aortic arch)curved continuation of the

ascending aorta

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arises posterior to the manubrium. ascends superolaterallydivides into right common carotid & right subclavian arteries.

BRACHIOCEPHALIC TRUNKfirst and largest branch of the arch of the aorta

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arises o posterior to the manubrium, o slightly posterior and to the left of the brachiocephalic trunk.

LEFT COMMON CAROTID ARTERYsecond branch of the arch of the aorta

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arises from the posterior part of the arch

posterior to left common carotid artery.

ascends lateral to trachea & left common carotid artery.

Leaves the thorax and enters the root of the neck.

LEFT SUBCLAVIAN ARTERYthird branch of the arch of the

aorta

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Abdominal aorta