Heart PositionExternal morphologyRelationsCardiac chambersConductionVesselsPericardium

Position• Lies within the pericardi

um in middle mediastinum

• Behind the body of sternum and coastal cartilages 2 to 6

• In front of thoracic vertebrae 5 to 8

• A third of it lies to the right of median plan and 2/3 to the left

External morphology

one apex,one base,two surfacesthree bordersthree grooves

the apex formed by the left ventriclethe base faces backward,upward and to the right. Formed mainly by the left atrium and partly by the right atrium.two surfaces: sternocostal and diaphragmatic surfacesthree borders: right,left and inferior borders *the cardiac apecal incisure is on the inferior border and right to the apex *atrioventricular crux is a point of the coronary and posterior interventricular grooves. It is a important superficial markthree grooves: coronary groove ant. interventricular groove post. interventricular groove

Chambers• right atrium• right ventricle• left atrium• left ventricle

—two parts(divided by the terminal crest) ant.part atrium proper post.part sinus *four openings orifice of the sup.vena cava

orifice of the inf.vena cava inlet orifice of the coronary sinus

the right atrioventricular orifice---outlet

*the fossa ovalis (oval foramen) *the triangle of Kock(tricuspid valves , orifice of the coronary sinus, tendon of todaro)

Atrioventricular node is located in.

Right ventricle

pulmonary valvetricuspid valves chordae tendineaepapillary muscles(3 groups)

inflow tracts outflow tracts(divided by the supraventricular crest)

Left atrium

left auricle —five openings*four orifices of the pulmonary veins*the left atrioventricular orifice

Left ventricle

※ the papillary muscles(2 groups)

inflow and outflow tracts(divided by the ant.cusp of the bicuspid valves)

structurethe walls of the heart3 layers—endocardium *continue with the lining of the large

blood vessels—myocardium *2 kinds: the ordinary cardiac muscle

s the specially m.— epicardium

• Septum interatrial septum----Oval fossa interventricular septum----Membranous part

Conduction SystemIt is consists of the special

cardiac muscles

5 parts: sinoatrial nodeatrioventricular node,atrio-ventricular bundleLeft and right branchesPurkinje fibers.

—The sinoatrial node(SAN) *It is lies the junction between the right auricle and the sup.vena cava —The atrioventricular node(AVN) *It is lies in the lower portion of the interatrial septum just above the orifice of the coronary sinus—Purkinje fibers

The vessels of the heart

The arteries—the right coronary a.*arise from the right aortic sinus and runs along th

e right portion of the coronary groove*2 branches: post.interventricular branch post.branch of the left venticle*To supply right atrium,right ventriclepost.1/3 of the interventricular septum,the diaphragmatic surface of left ventricle,the SAN and AVN. —The left coronary a. *arises from the left aortic sinus *2 branches: ant.interventricular br. circumflex br. *To supply the left atrium,left ventricle,the ant. su

rface of the right ventricle,ant.2/3 of the interventricular septum,sometimes, supply the

SAN and AVN.

2. The veins of the heart —The coronary sinus *It lies in the post.portion of the coronary sulcus between the left atrium and left ventricle *It opens into the right atrium *It receives: **the great cardiac v. **the middle cardiac v. **small cardiac v. —the other veins opening into the right atrium directly *the ant. cardiac v. *the smallest v.

Pericardium 1. It comprises 2 sacs: —the fibrous pericardium —the serous pericardium: *parietal layer *visceral layer2.The pericardial cavity: —the transverse sinus —the oblique sinus

Pericardium sinus• Transverse sinus of pericardium － posterior to ascending aorta

and pulmonary trunk, anterior to superior vena cava and left atrium.• Oblique sinus of pericardium － cul-de-sac , posterior to heart, b

ounded by pulmonary veins on either side