536 CARDIAC NERVES. 



rior, or the Small Cardiac Nerve. It originates from the 

 third, or lower cervical ganglion, by many fibrils which unite 

 into a smaller number that form a plexus. It crosses behind 

 the subclavian, and proceeds on the outside of the arteria inno- 

 minata to the curve of the aorta ; continuing between it and 

 the pulmonary artery, to the anterior coronary plexus. In this 

 course it receives several fibres from the recurrent and the par 

 vagum. 



On the left side the first cardiac nerve arises from the upper 

 ganglion. The second derives its origin from the two lower 

 ganglions. 



The left superior or superficial cardiac nerve arises like the 

 right, by many distinct fibres, and proceeds downwards in the 

 same way. It descends between the carotid and the subcla- 

 vian, and when it has arrived at the place where they origi- 

 nate from the aorta, it divides into a great number of small 

 ramifications. Some pass before the aorta, either to join the 

 branches of the inferior cardiac, or to unite with the cardiac 

 branches of the left nerve of the par vagum. The others pro- 

 ceed behind the aorta, and enter into the common cardiac 

 plexus. 



The second cardiac nerve of the left side may be called the 

 Great Left Cardiac, and has a double origin, as above men- 

 tioned. The principal branch in its composition arises from 

 the lowest cervical ganglion, and passes behind the transverse 

 portion of the subclavian artery. Where the inferior thyroid 

 artery arises from the subclavian, this branch receives a consider- 

 able number of ramifications, which arise from the upper gang- 

 lion, and are interwoven with each other before they unite to it. 

 It passes behind the curve of the aorta, and terminates in the 

 great cardiac plexus, which it particularly contributes to form. 

 Here it is joined by many fibres from the par vagum. 



The Cardiac Plexus 



Is situated principally behind the curve of the aorta, at a 

 small distance above the heart. It commences as high as the 



