THORACIC CAVITYTHORACIC CAVITY

HEARTHEART

Pericardial CavityPericardial CavityHeart is located in the middle inferior Heart is located in the middle inferior

mediastinum within the pericardial cavity.mediastinum within the pericardial cavity.

Visceral PericardiumVisceral PericardiumSerous membrane Serous membrane Fig 1.37, p 139)Fig 1.37, p 139)Referred to as epicardium.Referred to as epicardium.Arterial mesocardium.Arterial mesocardium.Venous mesocardium.Venous mesocardium.

Visceral PericardiumVisceral PericardiumTransverse sinus:Transverse sinus:

Space between arterial and venous Space between arterial and venous mesocardium.mesocardium.

Oblique sinus:Oblique sinus:Space between right and left pulmonary Space between right and left pulmonary

veins.veins.

PericardiumPericardiumPericardial cavity.Pericardial cavity.Parietal (serous):Parietal (serous):

Fused to fibrous pericardium.Fused to fibrous pericardium.Fibrous:Fibrous:

Fused with central tendon of diaphragm:Fused with central tendon of diaphragm:Pericardiacophrenic ligament.Pericardiacophrenic ligament.

Fused with sternum:Fused with sternum:Superior and inferior sternopericardial Superior and inferior sternopericardial ligaments.ligaments.

PericardiumPericardiumBlood supply (Fig. 1.38, p 139):Blood supply (Fig. 1.38, p 139):

Pericardial arteries.Pericardial arteries.Pericardiacophrenic arteries.Pericardiacophrenic arteries.Musculophrenic arteries.Musculophrenic arteries.

Nerve supply:Nerve supply:CN X.CN X.Phrenic nerve.Phrenic nerve.Sympathetic trunk.Sympathetic trunk.

Cardiac ProjectionsCardiac ProjectionsApex is down and to left.Apex is down and to left.Base of heart is superior to apex:Base of heart is superior to apex:

Upside down triangle.Upside down triangle.Base projection:Base projection:

Horizontal plane across sternum.Horizontal plane across sternum.Level of costal cartilage 3.Level of costal cartilage 3.Ends 2 cm to left of left parasternal line.Ends 2 cm to left of left parasternal line.

Cardiac ProjectionsCardiac ProjectionsApex projection:Apex projection:

55thth intercostal space. intercostal space.8 cm (interclavicular line) to left of median 8 cm (interclavicular line) to left of median line of sternum.line of sternum.

Pericardium extends up to sternal angle.Pericardium extends up to sternal angle.

Layers of the HeartLayers of the HeartExternal:External:

EpicardiumEpicardiumVisceral layer of serous pericardium + Visceral layer of serous pericardium + subserous layer of connective tissue.subserous layer of connective tissue.

Middle:Middle:Myocardium:Myocardium:

ThickestThickestCardiac muscle tissue.Cardiac muscle tissue.

Layers of the HeartLayers of the Heart Inner:Inner:

Endocardium:Endocardium:Endothelial layerEndothelial layer

Cardiac SkeletonCardiac Skeleton4 interlocking fibrous rings:4 interlocking fibrous rings:

Annuli fibrosi.Annuli fibrosi.Interconnected with membranous portion Interconnected with membranous portion

of of interventricular septum.interventricular septum.Fig. 1.40B, p 143)Fig. 1.40B, p 143)

Cardiac SkeletonCardiac Skeleton

Functions of annuli fibrosi:Functions of annuli fibrosi:Rigid attachment for cardiac muscle Rigid attachment for cardiac muscle

fibers.fibers.Support for valves.Support for valves.

External HeartExternal Heart Base:Base:

Posterior aspect of heart.Posterior aspect of heart.Mostly left atrium + small part of right atrium.Mostly left atrium + small part of right atrium.

Apex:Apex:Located at intercostal space 5 medial to Located at intercostal space 5 medial to nipple.nipple.Formed from left ventricleFormed from left ventricle

Fig. 1.42A, p 146.Fig. 1.42A, p 146.

External HeartExternal HeartDiaphragmatic surface:Diaphragmatic surface:

Rests on diaphragm.Rests on diaphragm.Mostly left ventricle and a small part of Mostly left ventricle and a small part of

right.right.Sternocostal surface:Sternocostal surface:

Faces anteriorly.Faces anteriorly.Mostly right ventricle.Mostly right ventricle.

External HeartExternal Heart

Left margin (border):Left margin (border):Left side of heart formed mostly of left ventricle Left side of heart formed mostly of left ventricle

and and left auricle.left auricle.

Inferior margin (border):Inferior margin (border):Intersection of diaphragmatic and sternocostal Intersection of diaphragmatic and sternocostal

surfaces.surfaces.Formed mostly from right ventricle.Formed mostly from right ventricle.

Superior border:Superior border:Left and right atria and auricles.Left and right atria and auricles.

Anterior Surface of HeartAnterior Surface of HeartCC: common carotid A.CC: common carotid A.AA:AA: aortic arch aortic archSC: subclavian V.SC: subclavian V.SVC: sup. VCSVC: sup. VCRPA: right pulmonary RPA: right pulmonary

artery.artery.RPV: right pulmonary RPV: right pulmonary

veins.veins.RCA: right coronary A.RCA: right coronary A.IVC: inferior vena cava.IVC: inferior vena cava.LA:LA: ligamentum ligamentum

arteriosumarteriosum

Anterior Surface of HeartAnterior Surface of HeartLPA: left pulmonary A.LPA: left pulmonary A.LPV: left pulmonary V.LPV: left pulmonary V.CB: circumflex branch CB: circumflex branch of of

left coronary A.left coronary A.LM: left marginal A.LM: left marginal A.LAD: left anterior LAD: left anterior

descending A.descending A.

Blood Supply to HeartBlood Supply to Heart

Blood supply to heart is via two Blood supply to heart is via two coronary arteries (Fig. 1.49A&B, 157):coronary arteries (Fig. 1.49A&B, 157):

Coronary arteries are the direct and only Coronary arteries are the direct and only branches off the ascending aorta.branches off the ascending aorta.

Right Coronary ArteryRight Coronary ArteryPasses between pulmonary trunk and right Passes between pulmonary trunk and right

auricle.auricle.To coronary sulcus.To coronary sulcus.Follows coronary sulcus to diaphragmatic Follows coronary sulcus to diaphragmatic

surface.surface.Anastomoses with left coronary artery.Anastomoses with left coronary artery.

Right Coronary Artery Supplies:Right Coronary Artery Supplies:Right atrium.Right atrium.Right ventricle.Right ventricle.Posterior half of interventricular septum.Posterior half of interventricular septum.

Right Coronary Artery BranchesRight Coronary Artery BranchesArtery to SA node.Artery to SA node.Artery to AV node.Artery to AV node.Right marginal artery.Right marginal artery.Posterior interventricular arteryPosterior interventricular artery

= posterior descending artery (PDA)= posterior descending artery (PDA)

Left Coronary ArteryLeft Coronary Artery

Passes between pulmonary trunk and Passes between pulmonary trunk and left atrium.left atrium.

Supplies:Supplies:Left atrium.Left atrium.Left ventricle.Left ventricle.Anterior half of interventricular septum.Anterior half of interventricular septum.

Left Coronary ArteryLeft Coronary Artery

Major branches:Major branches:Anterior interventricular artery (= left Anterior interventricular artery (= left

anterior anterior descending LAD).descending LAD).Circumflex artery.Circumflex artery.Left marginal artery.Left marginal artery.

Venous Drainage from HeartVenous Drainage from Heart Fig. 1.51, page 159Fig. 1.51, page 159Coronary sinus:Coronary sinus:

Located in posterior coronary sulcus.Located in posterior coronary sulcus.Opens into right atrium.Opens into right atrium.Direct continuation of great cardiac vein.Direct continuation of great cardiac vein.Tributaries:Tributaries:

Great cardiac vein.Great cardiac vein.Middle cardiac vein.Middle cardiac vein.Small cardiac vein.Small cardiac vein.

Right AtriumRight AtriumFig. 1.43, p 148:Fig. 1.43, p 148:Receives blood from:Receives blood from:

Superior vena cava.Superior vena cava.Inferior vena cava.Inferior vena cava.Coronary sinus.Coronary sinus.Anterior cardiac veins.Anterior cardiac veins.

Large, thin-walled chamber.Large, thin-walled chamber.

Right AtriumRight AtriumSub-chambers:Sub-chambers:

Main posterior cavity:Main posterior cavity:Sinus venarum.Sinus venarum.

Anterior cavity:Anterior cavity:Auricle.Auricle.Lined with pectinate muscles.Lined with pectinate muscles.

Right VentricleRight VentricleFig. 1.44, p 149Fig. 1.44, p 149Receives blood from right atrium.Receives blood from right atrium.Thicker walled than right atrium.Thicker walled than right atrium.Trabeculae carnae.Trabeculae carnae.Moderator band:Moderator band:

(septomarginal trabecula)(septomarginal trabecula)Conveys right branch of atrioventricular Conveys right branch of atrioventricular

bundle.bundle.

Right Atrioventricular ValveRight Atrioventricular ValveAlso called the tricuspid valve.Also called the tricuspid valve.Chordae tendinae.Chordae tendinae.Papillary muscles.Papillary muscles.Fig. 1.45 B&C, p 150Fig. 1.45 B&C, p 150

Right VentricleRight VentriclePulmonary valve:Pulmonary valve:

Formed from three semilunar cusps.Formed from three semilunar cusps.Pulmonary trunk:Pulmonary trunk:

Divides into left and right pulmonary Divides into left and right pulmonary arteries.arteries.

Left AtriumLeft AtriumLeft atrium (Fig. 1.46, p 152):Left atrium (Fig. 1.46, p 152):

Receives blood from four pulmonary veins.Receives blood from four pulmonary veins.Smaller and thicker-walled than right Smaller and thicker-walled than right

atrium.atrium.Posterior smooth portion receives Posterior smooth portion receives

pulmonary pulmonary veins.veins.Anterior portion = auricle:Anterior portion = auricle:

with pectinate muscles.with pectinate muscles.

Left VentricleLeft VentricleFig. 1.47, p 153Fig. 1.47, p 153Wall = 2-3 x as thick as wall of right Wall = 2-3 x as thick as wall of right

ventricle.ventricle.Trabeculae carnae are less coarse than Trabeculae carnae are less coarse than

those of right ventricle.those of right ventricle.No moderator band.No moderator band.Two large papillary muscles:Two large papillary muscles:

Anterior and posterior.Anterior and posterior.

Left Atrioventricular/Aortic ValvesLeft Atrioventricular/Aortic Valves

Left atrioventricular valve:Left atrioventricular valve:= bicuspid or mitral valve.= bicuspid or mitral valve.

Aortic valve:Aortic valve:Composed of three semilunar cusps.Composed of three semilunar cusps.

Conduction System of the HeartConduction System of the HeartComposed of modified specialized cardiac Composed of modified specialized cardiac

muscle cells.muscle cells.No nervous tissue in heart.No nervous tissue in heart.Fig. 1.52, p 163)Fig. 1.52, p 163)

Sinoatrial NodeSinoatrial NodeReferred to as pacemaker of heart.Referred to as pacemaker of heart.Located in right atrium near opening of Located in right atrium near opening of

SVC:SVC:Superior end of sulcus terminalis.Superior end of sulcus terminalis.

Receives direct stimulation from:Receives direct stimulation from:Sympathetic cardiac nerves.Sympathetic cardiac nerves.Parasympathetic vagus nerves.Parasympathetic vagus nerves.

Conduction System of the HeartConduction System of the HeartAtrioventricular node:Atrioventricular node:

Located in interatrial septum near tricuspid Located in interatrial septum near tricuspid valve.valve.

Interventricular bundle:Interventricular bundle:Descends through channel in fibrous Descends through channel in fibrous

skeleton.skeleton.Reaches membranous interventricular Reaches membranous interventricular

septum.septum.Only connection between myocardium of Only connection between myocardium of atria and that of ventricles.atria and that of ventricles.

Conduction System of the HeartConduction System of the Heart Interventricular bundle:Interventricular bundle:

Divides into two bundles in membranous Divides into two bundles in membranous portion:portion:

Right crus (bundle branches) passes Right crus (bundle branches) passes through through moderator band.moderator band.

Left crus (bundle branches)Left crus (bundle branches)

Conduction System of the HeartConduction System of the Heart

Purkinje fibers:Purkinje fibers:Terminal endings of bundle fibers.Terminal endings of bundle fibers.Embedded in myocardium of ventricle.Embedded in myocardium of ventricle.

Great VesselsGreat VesselsAscending aorta:Ascending aorta:

Runs behind sternum to sternal angle.Runs behind sternum to sternal angle.Only branches are the two coronary Only branches are the two coronary

arteries.arteries.Fig. 1.58, p 172Fig. 1.58, p 172

Arch of the AortaArch of the AortaLies within superior mediastinum.Lies within superior mediastinum.

Arches to the left over the left pulmonary Arches to the left over the left pulmonary artery.artery.

Apex of the arch reaches the middle of the Apex of the arch reaches the middle of the manubrium.manubrium.

Three main branches:Three main branches:Brachiocephalic.Brachiocephalic.Left common carotid.Left common carotid.Left subclavian.Left subclavian.

Arch of the AortaArch of the AortaAnterior relationships:Anterior relationships:

Left phrenic nerve.Left phrenic nerve.Left vagus nerve.Left vagus nerve.Superficial cardiac plexus.Superficial cardiac plexus.

Arch of the AortaArch of the Aorta Inferior relationships:Inferior relationships:

Left recurrent laryngeal nerve.Left recurrent laryngeal nerve.Ligamentum arteriosum.Ligamentum arteriosum.Pulmonary trunk.Pulmonary trunk.Left primary bronchus.Left primary bronchus.

Arch of the AortaArch of the AortaPosterior relationships:Posterior relationships:

TracheaTracheaLeft recurrent laryngeal nerve.Left recurrent laryngeal nerve.

Descending AortaDescending AortaLies within posterior mediastinum.Lies within posterior mediastinum.Begins at level of sternal angle.Begins at level of sternal angle.Ends in front of thoracic vertebra 12.Ends in front of thoracic vertebra 12.Continuous with abdominal aorta.Continuous with abdominal aorta.

Descending Aorta BranchesDescending Aorta BranchesPaired intercostal arteries.Paired intercostal arteries.Paired subcostal arteries.Paired subcostal arteries.Two or more bronchial arteries.Two or more bronchial arteries.Two to five esophageal arteries.Two to five esophageal arteries.

Other Thoracic VesselsOther Thoracic VesselsSupreme intercostal:Supreme intercostal:

From costocervical trunk of subclavian From costocervical trunk of subclavian artery.artery.

Supplies IC spaces one and two.Supplies IC spaces one and two. Internal thoracics:Internal thoracics:

Arise within root of neck.Arise within root of neck.Descend lateral to sternum.Descend lateral to sternum.

Internal Thoracic ArteriesInternal Thoracic ArteriesBranches:Branches:

Musculophrenic (terminal):Musculophrenic (terminal):To diaphragmTo diaphragmTo intercostal spaces 7-9To intercostal spaces 7-9

Superior epigastric (terminal)Superior epigastric (terminal)

Internal Thoracic ArteriesInternal Thoracic ArteriesBranches:Branches:

Pericardioacophrenic arteries:Pericardioacophrenic arteries:Accompanies phrenic nerve.Accompanies phrenic nerve.Supplies pericardium, mediastinal Supplies pericardium, mediastinal pleura, diaphragm.pleura, diaphragm.

Perforating branches:Perforating branches:Accompany anterior cutaneous Accompany anterior cutaneous branches of intercostal nerves.branches of intercostal nerves.Largest in intercostal spaces 2-4 in Largest in intercostal spaces 2-4 in females.females.

Right Brachiocephalic VeinRight Brachiocephalic VeinFrom:From:

Right internal jugular.Right internal jugular.Right subclavian.Right subclavian.

Tributary:Tributary:Right internal intercostal vein.Right internal intercostal vein.

Fig. 1.64, p 182Fig. 1.64, p 182

Left Brachiocephalic VeinLeft Brachiocephalic VeinFormed from:Formed from:

Left internal jugular vein.Left internal jugular vein.Left subclavian vein.Left subclavian vein.

Tributaries:Tributaries:Left internal thoracic vein.Left internal thoracic vein.Left superior intercostal.Left superior intercostal.Inferior thyroid veins.Inferior thyroid veins.

Superior Vena CavaSuperior Vena CavaFormed from:Formed from:

Right brachiocephalic vein.Right brachiocephalic vein.Left brachiocephalic vein.Left brachiocephalic vein.

Receives:Receives:Azygos vein.Azygos vein.

Azygos SystemAzygos SystemDrains most of blood from thoracic wall.Drains most of blood from thoracic wall.Consists of longitudinal veins lying on Consists of longitudinal veins lying on

either side of thoracic vertebral bodies.either side of thoracic vertebral bodies.Variable.Variable.

Azygos VeinAzygos VeinForms in abdomen:Forms in abdomen:From right subcostal and ascending From right subcostal and ascending

lumbar veins.lumbar veins.Drains all right posterior intercostal veins Drains all right posterior intercostal veins

except first.except first.Also receives blood from the bronchial and Also receives blood from the bronchial and

esophageal veins.esophageal veins.

Hemiazygos VeinHemiazygos VeinForms in abdomen:Forms in abdomen:From left subcostal and left ascending From left subcostal and left ascending

lumbar veins.lumbar veins.Receives four posterior intercostal veins.Receives four posterior intercostal veins.Crosses over thoracic vertebrae at T8 Crosses over thoracic vertebrae at T8

level.level.Empties into azygos vein.Empties into azygos vein.

Other Thoracic VesselsOther Thoracic Vessels

Accessory hemiazygos vein:Accessory hemiazygos vein:Drains intercostal spaces 4-7(8) on left side.Drains intercostal spaces 4-7(8) on left side.Crosses over thoracic vertebrae at level T7.Crosses over thoracic vertebrae at level T7.Empties into azygos vein.Empties into azygos vein.

Note: Intercostal space 1 is drained by the Note: Intercostal space 1 is drained by the supreme intercostal vein emptying into the supreme intercostal vein emptying into the brachiocephalic vein.brachiocephalic vein.