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AAAC08 23/05/2005 3:06 PM Page 22
8 The heart II

Left coronary Coronary
artery sinus
Right coronary
artery
Anterior
interventricular Great
branch cardiac
vein

Marginal Posterior Middle Small
Fig.8.1 artery interventricular cardiac cardiac
The coronary arteries. branch vein vein
Variations are common Fig.8.2
The venous drainage of the heart

Atrial conduction

S–A node
65

A–V node 0
50
55 P T
QRS
15 40

Fig.8.4
12
35 An electrocardiogram
Ventricular conduction
25 35
Fig.8.3
The direction and timing of the spread
of action potential in the conducting
system of the heart.
Times are in msec

22 Thorax