THE 
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VETERINARIAN. 
vol. iv. DECEMBER, 1831. No - 48 - 
ANATOMY OF THE HORSE. 
[Continued from page 490.] 
OF THE HEART AND PERICARDIUM. 
Situation .—The heart is inclosed within the pericardium; and 
both together occupy the middle space of the cavity of the 
thorax. 
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PERICARDIUM. 
The pericardium is a membrane formed into a conoid sac for 
the purpose of containing the heart. It has, exteriorly, an opaque 
white aspect; is dense in its consistence, and firm and tenacious 
in its texture. It is composed of two layers, intimately united by 
cellular tissue. The external one is dense and fibrous, is pos¬ 
sessed of the chief strength of the membrane, and is attached be¬ 
low by several ligamentary cords to the sternum and tendinous 
part of the diaphragm, and above to the roots of the large blood¬ 
vessels at the base of the heart, upon which we lose sight of it 
altogether: the sides of it are clothed and additionally strength¬ 
ened by the adhesions of the pleurae. The internal layer is fine 
and cellular, exhibits inwardly a smooth, polished surface, and 
appears to be similar to other serous membranes in its intimate 
texture and organization. It not only lines the external layer, and 
gives a covering to the roots of the large bloodvessels, but is re¬ 
flected from them upon the heart itself, to which it forms a close 
and complete tunic: so that the heart is absolutely out of (above) 
the cavity of the pericardium ; in fact, it is situated precisely the 
same in regard to this membrane, as the human head is in a 
double nightcap. 
The liquor pericardii is the pale yellow serous fluid found 
within the cavity of the pericardium, secreted therein by the ex- 
halents of the membrane. It serves to lubricate the contiguous 
surfaces of the sac, and to preserve them against any ill conse¬ 
quences from friction. 
The me of the pericardium is to confine the heart in its situ- 
vol. iv. 4 x 
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