Human Anatomy Vol 1

1 The great cardiac aein accompanies first the anterior
interventricular artery and then the left coronary
artery to enter the left end of the coronary sinus
(Fig. 18.2ea).
2 The middle cardiac oein accompanies the posterior
interventricrlar artery, and joins the middle part of
the coronary sinus.

3 The small cardiac uein accompanies the right coronary
artery in the right posterior coronary sulcus and joins
the right end of the coronary sinus. The right
marginal vein may drain into the small cardiac vein
(Fig. 18.2eb).

4 The posterior aein of the left ttentricle runs on the
diaphragmatic surfaee of the left ventricle and ends
in the coronary sinus.
5 The oblique aein of the left atrium of Marshall is a small
vein running on the posterior surface of the left
atrium. It terminates in the left end of the coronary
sinus. It develops from the left common cardinal vein
or duct of Cuvier which may sometimes form a large
left superior vena cava.
6 The right marginal uein accompanies the marginal
branch of the right coronary artery. It may either
drain into the small cardiac vein, or may open
directly into the right atrium.

Anterior Cordioc Veins

The anterior cardiac aeins are three or four small veins
which run parallel to one another on the anterior wall of
the right ventricle and usually open directly into the
right atrium through its anterior wall.

Venoe Cordis Minimi

The aenae cordis minimi or Thebesian aeins or smallest
cardiac aeins are numerous small valveless veins present
in all four chambers of the heartwhichopen directly into
the cavity. These are more numerous on the right side
of the heart than on the left. This may be one reason why
left sided infarcts are more common.

LYMPHATICS OF HEARI

Lymphatics of the heart accompany the coronary
arteries and form two trunks. The right trunk ends in
the brachiocephalic nodes, and the left trunk ends in
the tracheobronchial ly*ph nodes at the bifurcation of
the trachea.

NERVE SUPPLY OF HEARI

Parasympathetic nerves reach the heart via the vagus.
These are cardioinhibitory; on stimulation they slow
down the heart rate.
Sympathetic nerves are derived from the upper four
to five thoracic segments of the spinal cord. These are

PERICARDIUM AND HEART

cardio-acceleratory, and on stimulation they increase

the heart rate, and also dilate the coronary arteries.

Both parasympathetic and sympathetic nerves form

the superficial and deep cardiac plexuses, the branches

of which run along the coronary arteries to reach the

myocardium.

The sup erficial c ar diac ple xus is situated below the arch

of the aorta in front of the right pulmonary artery. It is

formed by:

a. The superior cervical cardiac branch of the left

sympathetic chain.

b. The inferior cervical cardiac branch of the left

vagus nerve.

The plexus is connected to the deep cardiac plexus,

the right coronary artery, and to the left anterior

pulmonary plexus (Fig. 18.30).

The deep cardiac plexus is situated in front of the

bifurcation of the trachea, and behind the arch of the

aorta. It is formed by all the cardiac branches derived

from all the cervical and upper thoracic ganglia of the

sympathetic chain, and the cardiacbranches of thevagus

and recurrent laryrrgeal nerves, except those which form

the superficial plexus. The right and left halves of the

plexus distribute branches to the corresponding

coronary and pulmonary plexuses. Separate branches

are given to the atria.

. Cardiac pain is an ischaemic pain caused by
incomplete obstruction of a coronary artery.
. Axons of pain fibres conveyed by the sensory
sympathetic cardiac nerves reach thoracic one to
thoracic five segments of spinal cord mostly
through the dorsal root ganglia of the left side.
Since these dorsal root ganglia also receive sensory
impulses from the medial side of arm, forearm and
upper part of front of chest, the pain gets referred
to these areas as depicted in Fig. 18.26.
. Though the pain is usually referred to the left side,
it may even be referred to right arm, jaw,
epigastrium or back.

Developmenlol Components

L Right atrium (Fig. 18.11)

a. Rough anterior part-atrial chamber proper.

b. Smooth posterior part-

• Absorption of right horn of sinus venosus


• Interatrial septum
  Demarcating part-crista terminalis.
  2 Left atrium (Figs 18.16 and 18.29b)
  a. Rough part-atrial chamber proper
  b. Smooth part-


• Absorption of pulmonary veins.


• Interatrial septum.

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