Basics of anatomy

1. Anatomy of the heart
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Cone shaped muscle
4 chambers:
- 2 atria : right atrium (RA) & left atrium( LA) , separated by
interatrial septum (IAS)
- 2 ventricles: right ventricle (RV) & left ventricle (LV) ,
separated by inter-ventricular septum (IVS)
4 Valves ( 3 tricuspid &1 bicuspid):
- 2 Rt sided valves: Tricuspid valve( TV) & pulmonary valve (
PV)
- 2 Lt sided: Mitral valve( MV) & aortic valve (AV).
Two circulations
- Systemic circuit: blood vessels that transport blood to and from
all the body tissues
- Pulmonary circuit: blood vessels that carry blood to and from
the lungs

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3. Two circulations
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4. Borders of the heart
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 Right ventricle ( RV) : Forms 2/3 anterior surface,
1/3 inferior surface.
 Left venticle (LV) : forms the apex , 1/3 anterior
surface ,2/3 inferior surface
 Left atrium (LA) :Forms the posterior surface or
base.
 Right atrium (RA) : Right border of heart

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6. Layers of the heart wall
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 Muscle of heart = myocardium
 Coverings of the heart: pericardium
 1) Fibrous pericardium
 2) Serous pericardium :2 layers
Parietal serous layer
Visceral serous layer = epicardium:
Between the layers = pericardial cavity
 Endocardium lining the chambers

7. Conduction system
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 SA (sinoatrial) node
- High in the right atrium (RA).
- Predominant cardiac pacemaker: from which impulse
spread in all directions in both atria
- Impulse also to AV node via internodal pathway
 AV(atrio-ventriuclar) node:
- Low in theright atrium (RA).
- Slows electrical conduction sufficiently to protect
ventricles from rapid heart rate coming from atria.

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 Atrioventricular bundle (Common bundle of His)
- Extend from AVN to summit of IVS.
- Divides into Rt,Lt bundle branches (RBB,LBB):
1) Spread down interventricular , then up free walls of RV, LV.
2) Give branches (“Purkinje fibers”)
- LBB: further subdivided into Lt antero-superior
fascicle (LAF), Lt infero-post fascicle (LPF):

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10. Heart sounds
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 Called S1 and S2
 1st heart sound ( S1) : is the closing of AV (Mitral and
Tricuspid) valves at the start of ventricular systole
 2nd heart sound (S2): is the closing of the semilunar (Aortic
and Pulmonic) valves at the end of ventricular systole.
 Additional sounds: S3 and S4 usually pathologic.
 Murmurs: the sound of turbulent blood flow across narrow
orifice: Can be normal (Innocent) or abnormal.

11. Blood supply of the heart
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Left main coronary artery ( LMCA):
1- Originates from aorta (Lt aortic sinus)
2- Divides into : LAD ,LCX ( may be ramus intermedius).
1)Left anterior descending artery ( LAD):
- Courses along ant surface of the heart then around apex.
- Give 1-3 diagonal branches (to antero-lateral wall), many septal
branches (to septum).
2) Left circumflex artery ( LCX):
- Courses around Lt border of heart to reach post wall of the heart.
- Gives 1-3 OM(obtuse marginal branches (to lateral wall), 1-2
LA branches (to lateral , post aspect of LA).
- LCX dominant in 10% if gives posterior descending artery
(PDA).

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Right coronary artery (RCA):
- Originates from aorta ( Rt aortic sinus). Courses around Rt
border of heart to reach posterior border of heart.
- Gives conus branch , SAN branch , atrial , RV branches.
- If RCA is dominant (85%), RCA (after giving posterior
descending artery : PDA) continue as postero-lateral(PL)
branch.

14. Venous drainage of the heart
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 Coronary sinus:
- Wide venous channel 4 cm length, lying in posterior
atrio-ventricular groove(between posterior& inferior
surfaces)of heart.
- Drains most of cardiac veins (Great, middle, small
cardiac veins & oblique vein of left atrium).
- Opens (has a valve) into right atrium

15. Nerve supply of the heart
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 Autonomic (sympathetic, parasympathetic fibers) via
cardiac plexus of nerves .
 Function:
- HR control (↑ by sym& ↓ by para).
- No sympathetic innervation to the ventricles but to atria
only.

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ThankYou