500 PNEUMOGASTRIC NERVE. 



The superior laryngeal also arises from the inferior gang- 

 lion, and taking an arched course downward behind the 

 internal carotid artery, enters the thyro-hyoid membrane 

 along with the superior laryngeal artery, and principally 

 supplies the mucous membrane of the larynx. This nerve 

 is regarded as one of sensation. 



The cardiac nerves have their origin from the vagus at 

 the root of the neck, by two or three branches, which cross the 

 carotid artery and join the sympathetic in the cardiac plexus. 



The inferior laryngeal (or recurrent nerve) comes from 

 the par vagurn upon the right side, as it crosses the sub- 

 clavian artery. It curves around and behind this artery, 

 and ascends to the larynx along the side of the trachea, 

 covered by the inferior thyroid and common carotid arte- 

 ries ; at its origin it gives off filaments to the cardiac plexus, 

 trachea, oesophagus, and thyroid gland, and finally termin- 

 ates by supplying all the muscles of the larynx except the 

 crico-thyroid. Branches have also been traced into the 

 mucous membrane of the larynx. 



The recurrent of the left side differs from that of the 

 right, in curving round the arch of the aorta and ductus 

 arteriosus. The recurrent, or inferior laryngeal nerves are 

 essentially motor. 



Pulmonary brandies. These come from the vagus, near 

 the root of the lungs, and form a plexus, in front and be- 

 hind the root, called the anterior and posterior pulmonary 

 plexuses. The posterior is the larger, and both anastomose 

 with the sympathetic and phrenic nerves, and accompany 

 the pulmonary vessels and bronchial tubes, to supply the 

 lungs. 



(Esopliageal branches. These come from the pneumogas- 

 tric above and below the root of the lung; but it is below 

 the root that the nerves, on either side, come together, 

 and,, surrounding the oesophagus, constitute the cesophageal 

 plexus. The left vagus goes in front, while the right passes 

 behind the cesophagus. 



Gastric branches. These are the terminating branches of 

 the pneumogastric upon the stomach. They form, around 



