Human Anatomy Vol 1

anteriorlyby the ascending aorta and pulmonary trunk,
and posteriorly by the superior vena cava and inferiorly
by the left atrium; on each side it opens into the general
pericardial cavity (Fig. 18.5).
The oblique sinus is a narrow gap behind the heart. It
is bounded anteriorly by the left atrium, and posteriorly
by the parietal pericardium and oesophagus. On the
right and left sides it is bounded by reflections of
pericardium as shown in Fig. 18.5. Below, and to the
left, it opens into the rest of the pericardial cavity. The
oblique sinus permits pulsations of the left atrium to
take place freely (Figs 18.4 and 18.5).

Conlents of the Pericordium

1 Heart with cardiac vessels and nerves.
2 Ascending aorta.
3 Pulmonary trunk.

Ascending aorta

Arterial tube of pericardium

Pulmonary trunk

Arrow in transverse sinus

Left pulmonary veins

Arrow in oblique sinus

Right pulmonary veins
lnferior vena cava
Fig, 18.4: The pericardial cavity seen after removal of the heart.
Note the reflections of pericardium, and the mode of formation
of the transverse and oblique sinuses

PERICARDIUM AND HEART

4 Lower half of the superior vena cava.

5 Terminal part of the inferior vena cava.

5 The terminal parts of the pulmonary veins.

BIood Supply

The fibrous and parietaT pericardia are supplied by

branches from:

1 Internal thoracic.

2 Musculophrenic arteries.

3 The descending thoracic aorta.

4 Veins drain into corresponding veins

Nerve Supply

The fibrous and parietal pericardia are supplied by the

phrenic nerves. They are sensitive to pain. The

epicardium is supplied by autonomic nerves of the

heart, and is not sensitive to pain. Pain of pericarditis

originates in the parietal pericardium alone. On the

other hand, cardiac pain or angina originates in the

cardiac muscle or in the vessels of the heart.

Collection of fluid in the pericardial cavity is

referred to as pericardial effusion or cardiac

tamponade. The fluid compresses the heart and

restricts venous filling during diastole. It also

reduces cardiac output. Pericardial effusion can

be drained by puncturing the left fifth or sixth

intercostal space just lateral to the sternum, or in

the angle between the xiphoid process and left

costal margin, with the needle directed upwards,

backwards and to the left (Fig. 18.6,).

In mitral stenosis left atrium enlarges and com-

presses the oesophagus causing dysphagia.

Pulmonary

trunk

Arrow in

transverse

sinus

Ascending

aorta

Right atrium

Left pulmonary vein Right

pulmonary

Left oblique sinus veln

Fig. 18.5: Transverse section through the upperpartof the heaft.
Note that oblique sinus forms posterior boundary of left atrium

Parietal pericardium

Fig. 18.6: Drainage of pericardial effusion