Exercise 35

Anatomy of the Heart

Gross anatomy of the heart

Localized in the mediastinum It has a pointed apex

At the level of the 5th intercostal space And a broad base

Beneath the 2nd ribIs the site of emerging of the great vessels

Pericardial cavity Visceral pericardium or epicardium Parietal pericardium

Pericardial fluid Pericardial sac (fibrous)

Stabilizes the heart and its vessels Pericarditis

The pericardium

The Location of the Heart in the Thoracic Cavity

Figure 20.2c

Gross anatomy of the heart

MyocardiumMuscle wall of the heartFibrous skeleton of the heart

Endocardium

The heart consists of four chambersTwo atria

• Two auricles Two ventricles

Major blood vessels of the heart include Inferior and superior vena cavaeAorta, pulmonary trunk and pulmonary veins

Superficial Anatomy of the Heart

The Superficial Anatomy of the Heart

The Superficial Anatomy of the Heart

Figure 20.3b, c

Atria Thin walled upper chambers that receive blood

from the vena cava Ventricles

Thick walled lower chambers separated from the atria by AV valves

The superficial Anatomy of the heart

Right atrium (RA)Receives blood coming from the body via

superior, inferior vena cava and coronary sinusauricle

Right ventricle (RV)Receives blood from the RA and pumps it into

the pulmonary trunk Pulmonary trunk

Left and right pulmonary arteries

External anatomy of the heart and blood flow

External anatomy of the heart and blood flow

Lungs Pulmonary veins

2 rights and 2 lefts Left atrium (LA)

Receives blood from the pulmonary veinsAuricle

External anatomy of the heart and blood flow

Left ventricle (LV)Pumps blood into the aorta

AortaAscending, arch, descending

Ligamentum arteriosumRemnant of the ductus arteriosusBetween pulmonary artery and aorta

Blood supply to the heart

Coronary arteriesRight

• Posterior interventricular artery• Marginal• Supplies posterior part of the ventricles and

lateral part of the right heart

Blood supply to the heart

Left coronary• Anterior interventricular artery• Circumflex• Supplies the anterior part of the

ventricles and laterodorsal part of the heart

Blood Supply to the Heart - veins

Veins that empty into the coronary sinusGreat cardiac vein, posterior cardiac vein,

middle cardiac vein, small cardiac vein Anterior cardiac veins empty into the RA.

Coronary Circulation

Figure 20.9a, b

The Sectional Anatomy of the Heart

Internal anatomy of the heart

Right atriumFossa ovalis

• Foramen ovaleOpenings of the superior and inferior vena cavasPectinate muscleSA and AV nodesInteratrial septum

• Wall between atria

Internal anatomy of the heart

Right ventricleTricuspid valveChordae tedineaePapillary musclesTrabeculae carneae – muscular ridgesInterventricular septum

• Wall between ventricles

Internal anatomy of the heart

Moderator band (septomarginal band)• Horizontal muscular ridge• Brings the impulse to the papillary muscles• Only present in the RV

Conus arteriosus• Conical pouch from which the pulmonary

artery arises

Internal anatomy of the heart

Left atriumPrincipal cavity (sinus)Pectinate muscles on the auricle onlyOpenings of the pulmonary veins

Internal anatomy of the heart

Left ventricleBicuspid valveTrabeculae carneaePapillary musclesChordae tendineae

Valves of the Heart

Figure 20.8a

Valves of the Heart

Figure 20.8b

Valves of the heart

Bicuspid or mitral or left AV Tricuspid or right AV Aortic semilunar Pulmonary semilunar

The intrinsic conducting system

Functional syncytiumGap junctions

The intrinsic conducting system

The intrinsic conducting system

Controlling system over the heartAutonomic nervous system

• Sympathetic• Parasympathetic

Intrinsic conducting system or nodal system• Specialized myocardial tissue• Initiates the heart beat

The conducting system includes:Sinoatrial (SA) node (80-100 bpm)

• Contain the pacemaker cells• Located in the right atrium

Atrioventricular (AV) node (40-60 bpm)• Located in the atrium septum at the junction

of the atria and ventricles

The Intrinsic Conducting System

The Intrinsic Conducting System

AV bundle or bundle of His• Located in the interventricular septum

Right and Left bundle branches• Located in the interventricular septum

Purkinje fibers• Located in the myocardium• Larger in the left ventricle

SA node begins the action potential Stimulus spreads across the atria Stimulus spreads to the AV node Atrial contraction Impulse then travels through the AV bundle Impulse reaches right and left bundle branches

Steps for the heart beat

Steps for the heart beat

Then it reaches the Purkinje fibers Impulse reaches the papillary muscles

(via moderator band on the right side) Impulse is spread to the ventricles Ventricular contraction

The Intrinsic Conducting System

Pulmonary and systemic circulation

Pulmonary circulation

Pulmonary arteriesLeave the RVCarry blood rich in CO2Blood flows to the lungs

Pulmonary veinsLeave the lungBlood rich in O2Blood flows to the LA

Systemic circulation Aorta

Leaves the LVBlood rich in O2Blood flows to the body

Vena cavaSuperior brings blood from head, neck, arms and

superior trunkInferior brings blood from the rest of the bodyBlood rich in CO2Blood flows to the RA

Microscopic anatomy of the heart

Involuntary Cardiac cells

Intercalated discsBranchingCentral nucleusStriations

Identify these structure on the fresh heart

RAAuriclePectinate musclesSuperior and inferior vena cavasCoronary sinusTricuspid valve

Identify these structure on the fresh heart

RVPapillary musclesChrodae tendineaeTrabeculi carneaeModerator bandPulmonary trunk and its semilunar valve

Identify these structure on the fresh heart

LAAuriclePectinate muscles

Identify these structure on the fresh heart

LVMyocardiumPapillary musclesChordae tendineaeMitral valveTrabeculi carneaeInterventricular septumAorta and its semilunar valveCoronary arteries