PAR VAGUM. 



337 



branches of the superior laryngeal of the 

 opposite side, and with the arytenoid branch 

 of the recurrent; and occasionally a filament 

 perforates the arytenoid cartilage to reach the 

 inner surface of the larynx. 



Vascular and cardiac branches. The vagus 

 in its passage along the neck sends oft' directly 

 from its trunk several filaments, which throw 

 themselves into the arterial nervous plexuses sur- 

 rounding the carotid arteries and their branches ; 

 and also others which pass downwards and 

 join themselves, either directly or indirectly, to 

 the cardiac plexus. These branches are very 

 variable in their number, size, and origin, so 

 that it is impossible to give any description of 

 them which will be found generally applicable, 

 and they commonly differ on the two sides in 

 the same individual. 



Vascular br-anches (rami vasculares). 

 Several small branches arise from the trunk of 

 the vagus between the origin of the superior 

 laryngeal nerve, and about a line or so below 

 the level of the bifurcation of the common 

 carotid, and chiefly pass upon the carotid 

 arteries and their branches. Valentin* has 

 divided these into 



1. Rami carotid, consisting of two or three 

 larger and some smaller twigs, coming off 

 from the vagus near the origin of the superior 

 laryngeal and also from the commencement of 

 the superior laryngeal. They run inwards and 

 forwards upon the internal carotid. 



2. Ramus ad divisionem arteria carotidis is 

 principally distributed upon the common carotid 

 at its bifurcation. 



3. Ruiiii vasculares posteriores et interni are 

 generally three in number, come from that part 

 of the trunk of the vagus on a level with the 

 bifurcation of the common carotid, and run 

 principally, as their name implies, to the 

 nervous plexus on the posterior and inner part 

 of the large neighbouring arteries. 



4. Rami vasculares unteriores et interni 

 spring from the trunk of the vagus a very little 

 below the origin of the last, run to the outer 

 side of the common carotid, and assist with 

 some of the other branches of the vagus and 

 sympathetic in forming a nervous network on 

 the outer and anterior side of this artery, while 

 one or more twigs proceed downwards to join 

 the superior cardiac nerve of the vagus. 



Cardiac nerves. Two or three cardiac bran- 

 ches come from the inner side of the vagus at 

 some little distance from each other; the upper 

 of these generally arises a little below the bifur- 

 cation of the common carotid. These bran- 

 ches proceed downwards and inwards, commu- 

 nicate freely with each other, send some filaments 

 upon the surface of the common carotid artery, 

 anastomose freely with the cardiac branches of 

 the superior and middle cervical ganglia of the 

 sympathetic and with the recurrent, pass chiefly 

 in front of the large arteries at the root of the 

 neck, and terminate in the upper part of the 

 cardiac plexus of nerves. Frequently, more 

 especially when the upper cardiac branches 

 are small, or when some of them are want- 



* Op. tit. 



ing, we find a pretty large cardiac branch 

 arising from the vagus about the upper part of 

 the lower third of the neck, and passing down- 

 wards, on the right side in front of the subcla- 

 vian, on the .left in front of the arch of the 

 aorta, it throws itself into the upper part of the 

 cardiac plexus. Two or more branches also 

 leave the trunk of the vaus as it passes the 

 subclavian on the right and the arch of the aorta 

 on the left side, pass inwards and throw them- 

 selves partly into the cardiac plexus and partly 

 into the anterior bronchial plexus. 



Inferior laryngeal or recurrent branch. 

 ( Raiinis lari/ngeus inferior seu recurrens.) On 

 the right side the recurrent arises from the vagus 

 as it is passing over the anterior surface of the 

 subclavian artery, while on the left side it is 

 sent off from the vagus, generally from its inner 

 side, as it is crossing the anterior surface of the 

 transverse portion of the arch of the aorta. On 

 the right side it hooks round the subclavian on 

 the inner side of the scalenus anticus muscle, 

 and passing upwards and inwards, first below 

 the subclavian artery and then below the com- 

 mon carotid, it reaches the right side of the 

 trachea. On the left side it hooks round the 

 arch of the aorta and obliterated ductus arte- 

 riosus, and passing upwards and inwards below 

 the aorta, the left subclavian at its origin, and 

 the left common carotid, it reaches the left side 

 of the trachea. The recurrent soon after its 

 origin generally receives one or two additional 

 twigs from the trunk of the vagus. Immedi- 

 ately after it leaves the trunk of the vagus, it 

 anastomoses freely with branches of the sympa- 

 thetic, chiefly with the internal branches of the 

 two inferior cervical and first dorsal ganglia of 

 the sympathetic, and while the right sends 

 some twigs upon the outer surface of the sub- 

 clavian artery, the left sends some upon the 

 surface of the aorta. It also throws several 

 twigs into the cardiac, tracheal, and bronchial 

 plexuses. The left sends some twigs to the 

 tracheal plexus, while the corresponding twigs 

 of the right side come from the trunk of the 

 vagus. The two recurrents then proceed up- 

 wards along the sides of the trachea towards 

 the larynx, the left resting upon the anterior 

 surface of the oesophagus, and are both co- 

 vered by the sterno-hyoid and sterno-thyroid 

 muscles. In this part of the course of the re- 

 current it generally receives communicating 

 twigs from the cardiac branches of the superior 

 and middle cervical and sympathetic ganglia, 

 and it also anastomoses with some of the upper 

 . cervical cardiac branches of the va^us. It also 

 sends several twigs to the oesophagus and tra- 

 chea, (etsophageal and tracheal twigs of the 

 recurrent,) some of which perforate the fibrous 

 membrane between the cartilaginous rings of 

 the trachea, and reach its mucous surface, while 

 others are distributed among the muscular 

 fibres which complete the cartilaginous rings 

 behind. As it approaches the larynx it sends a 

 twig upwards and forwards, which anastomoses 

 with a descending twig of the external branch 

 of the superior laryngeal ; and it gives 

 some filaments to the thyroid body, to 

 the mucous membrane of the lower part of 



