786 THE NERVES. 



cervical nerves, and thus carries in a mass, to the great sympathetic, the 

 contingent of afferent nerve-fibres of the majority of these nerves 

 (Fig. 362, 24'). 



The other branch is an isolated one, proceeding from the eighth cervical 



pair. 



Besides these afferents, there ought to be noticed the filaments sent by 

 the pneumogastric nerve, and which join the middle cervical ganglion, when 

 it is present. See the description of the pneumogastric nerve. 



EMERGENT BRANCHES. These are detached from the posterior and 

 inferior part of the ganglion, and for the most part proceed to the heart. 

 Some extremely fine filaments go to the anterior mediastinum, or pass on to 

 the collateral arteries of the brachial trunk. 



The cardiac nerves (Fig. 362, 5) cross the base of the pericardium, 

 alongside the common aorta, and are then distributed to the tissue of the 

 auricles and ventricles. Some follow the divisions of the pulmonary artery, 

 and concur in the formation of the bronchial plexus. 



To arrive at the heart, these nerves accompany the axillary arteries and 

 the trachea, giving rise, on the inferior face of the latter, to a very large 

 fasciculus, named, in Veterinary anatomy, the tracheal plexus; this is single, 

 and is traversed from behind to before by the two recurrent nerves, which give 

 or receive from it numerous filaments. 



The cardiac nerves in the Horse are five in number ; two proceed from 

 the left, and three from the right cervical ganglion. Of the first two, one is 

 formed by easily-separated filaments, and is applied to the left brachial 

 trunk of the anterior aorta, which it follows to its commencement. There 

 it divides into several ramuscules ; some of these pass into- the furrow 

 between the right auricle and the origin of the pulmonary artery ; the 

 others pass between the latter and the common carotid, to reach the root of 

 the lung. This nerve furnishes very fine filaments to the anterior border of 

 the heart. The second left cardiac nerve commences by two branches that 

 leave the middle and inferior cervical ganglia ; from their union results 

 a long cord that is directed downward, backward, and to the right, crossing 

 the lower face of the trachea ; arrived at the right side of the posterior aorta, 

 beneath the recurrent nerve, it is distributed to the heart and lungs. 



The cardiac nerves arising on the right side are thus disposed. The 

 largest emerges from the middle cervical ganglion, and lies alongside the 

 pneumogastric, bending with it beneath the axillary artery, and becoming 

 detached a little beyond that vessel ; here it receives ramuscules from the 

 left recurrent and enters the base of the heart, after giving off some filaments 

 that pass to the bronchial plexus. The second, much smaller, is also 

 detached from the middle ganglion, receives some branches from the right 

 recurrent, and is applied to the surface of the anterior aorta as far as the 

 upper face of the auricles. Lastly, the third, as large as the preceding, 

 proceeds from the right recurrent, the inferior cervical ganglion, and the 

 pneumogastric ; it is imbedded in the heart, to the right of the aorta. 



3. Dorsal Portion of the Sympathetic Chain. 



The cord represented by this portion of the sympathetic chain leaves the 

 inferior cervical ganglion, and extends from before to behind, towards the 

 diaphragm, passing beneath the superior extremities of the ribs or rather, 

 below the vertebro- costal articulations, against which it is maintained by the 

 pleura and crossing the intercostal arteries. It is continued in the abdominal 



