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located in the coronary sulcus on the posterior surface of the 
heart. 
It has the following vessels: 
● v. cordis magna which begins on the anterior surface of 
the heart and goes along anterior interventricular septum; 
● v. cordis media is located in the posterior interventricular 
sulcus; 
● v. cordis parva is located in the right part of coronary 
artery; 
● v. posterior ventriculi sinistri is located on the posterior 
wall of left ventricle; 
● v. obliqua atrii sinistri is located on the wall of left 
pulmonary atrium.
 
The smallest cardiac veins or Thebesius – Vieussens veins 
(vv. cardis minimae) in the amount of 20 – 30 small vessels go 
to the right heart cavity. In cardiac strain (respiratory 
insufficiency) these vessels drain blood to the right pulmonary 
atrium.
Heart innervation
is provided by branches of cervical and 
thoracic segments of sympathetic trunk and also by branches 
of vagus nerves (parasympathetic innervation). They form 
plexus cardiacus on aorta and pulmonary trunk, the branches 
of which go to the cardiac muscle.
There are many parasympathetic fibres in the ascending part 
of aorta and pulmonary trunk which are the part of vagus nerves 
and recurrent laryngeal nerves. Parasympathetic nervous fibres 
slow down cardiac rhythm and narrow coronary arteries. That is 
why during the treatment of patients who suffer coronary heart 
disease plexotomia and coronary artery bypass graft are 
performed. Plexotomia or cutting of antenodal parasympathetic 
nervous fibres eliminates coronary arteries spasm. On the other 
hand cutting of antenodal parasympathetic nervous fibres 

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eliminates pain syndrome. 
Cardiac conduction system plays an important role in 
phisiology and pathology. 
Сardiac conduction system (complexus stimulans cordis, 
s. systema conducente cordis) consists of Keith – Flack node, 
Aschoff – Tawara node, His bundle which branches in to right 
and left foot. 
Keith – Flack node (nodus sinuatrialis) is atypical 
cardiomyocytes which are located under the epicardium on 
anterior surface of right atrium in the place of its merging with 
v. precava. Its cells are grouped around the central artery of 
Keith – Flack node. Keith – Flack node is the pacemaker and 
the source of cardiac automatism, the place of cardiac impulse 
formation.
Aschoff – Tawara node (nodus atrioventricularis) is located 
under endocardium of right atrium in its inferior-anterior 
segment. The node goes into the right fibrous triangle which is 
located in the place of right tricuspid, bicuspid and aortic 
valves junction and then it goes into atrioventricular bundle.
Atrioventricular bundle goes through membrane of 
interventricular septum and branches into left and right foot.
A slow rhythm of heart rate (less than 40 beats/min)
causes anemia, vertigo and loss of consciousness.
In ineffecient treatment of this condition with 
antiarrhythmic agents the surgical treatment is prescribed. It is 
implantation of cardiac pacemaker. It is sewed under 
hypodermic tissue of infraclavicular part. Electrodes are 
conducted through the subclavian vein into the right ventricle. 
From the congenital heart defects ductus arteriosus is mostly 
observed. It is a vessel through which the pathological 
conjunction of aorta and pulmonary trunk is observed after birth. 
The arterial canal branches off from the aortic arch at the 
left subclavian artery and goes obliquely up and down 

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entering the branching of the pulmonary trunk branching. 
Mediastinal pleura covers the arterial canal anteriorly. There 
are two nerves passing anteriorly to ductus arteriosus: vagus 
nerve and phrenic nerve. The recurrent laryngeal nerve rounds 
it behind, goes up and passes between the posterior wall of 
arterial canal and left main bronchus.

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