Seereeneye Geyer. 
THE TENTH OR PNEUMOGASTRIC NERVE. 651 
nerves : (1) with the superior cervical ganglion of the sympathetic ; (2) with the hypo- 
elossal ; (3) with the loop between the first and second cervical nerves ; and (4) with the 
accessory part of the spinal accessory nerve. This part of the nerve applies itself to the 
ganglion, and thereby supplies to the vagus nerve the inhibitory fibres for the heart, as 
well as the motor fibres for the pharynx, cesophagus, stomach and intestines, larynx and 
respiratory organs. 
Branches of the Pneumogastric in the Neck.—In the neck the pneumo- 
gastric nerve supplies cardiac branches and (on the right side) the inferior or 
recurrent laryngeal nerve (Fig. 467). 
The cardiac branches are superior and inferior. On the right side both cardiac 
branches pass downwards into the thorax behind the subclavian artery, and proceed 
alongside the trachea to join the deep cardiac plexus. On the left side the two 
nerves separate on reaching the thorax. The superior nerve passes deeply along- 
side the trachea to join the deep cardiac plexus. The inferior nerve accompanies 
the pneumogastric nerve over the aortic arch, along with the superior cervical 
cardiac branch of the sympathetic, to end in the superficial cardiac plexus. 
The right inferior laryngeal nerve arises at the root of the neck, as the 
pheumogastric nerve crosses over the first part of the subclavian artery. It hooks 
round the artery, and passes obliquely upwards and inwards behind the subclavian, 
the common carotid, and the inferior thyroid artery and the thyroid body. It finally 
disappears beneath the lower border of the inferior constrictor muscle, and ends 
in supplying the muscles of the larynx. In its course it gives off the following 
branches :-— 
(1) Cardiac branches arise as the nerve winds round the subclavian artery, and 
course downwards alongside the trachea to end in the deep cardiac plexus. 
(2) Communicating branches to the inferior cervical ganglion of the sympathetic 
arise from the nerve behind the subclavian artery. 
(3) Muscular branches supply the trachea, cesophagus, and the inferior constrictor 
of the pharynx. 
(4) Terminal branches supply the muscles of the larynx (except the crico-thyroid) 
and communicate beneath the ala of the thyroid cartilage with branches of the 
internal laryngeal nerve. 
Branches of the Vagus in the Thorax.—In the thorax the pneumo- 
gastric nerve forms the great pulmonary and cesophageal plexuses. The right 
nerve, in addition, furnishes cardiac branches; and the left nerve gives off the 
inferior or recurrent laryngeal nerve. 
The left inferior laryngeal nerve differs from the nerve of the right side only 
in its point of origin and in the early part of its course. It springs from the 
pheumogastric nerve as it crosses the aortic arch, and, after hooking round the 
arch external to the ligamentum arteriosum, it passes upwards in the superior 
mediastinum in the interval between the trachea and cesophagus to the neck. In 
the neck its course and relations ave similar to those of the nerve of the right side. 
The branches of the nerve are the same as those of the right nerve. The cardiac 
branches are larger, and, arising below the aortic arch, proceed to the deep cardiac 
plexus. 
Cardiac branches from the right pneumogastric nerve arise in the superior 
mediastinum, and pass downwards alongside the trachea to join the deep cardiac 
plexus. On the right side thoracic cardiac branches are thus supplied from both 
the trunk of the nerve and its recurrent branch ; on the left side the cardiac branches 
in the thorax arise solely from the recurrent branch. 
Abdominal Branches.—After the formation of the cesophageal plexus the 
two pneumogastric nerves resume their course, and passing along with the gullet 
through the diaphragm, terminate by supplying the stomach. The right nerve 
enters the abdominal cavity behind the gullet, and is distributed to the posterior 
surface of the stomach. It sends communicating offsets to the cceliac, splenic, and 
renal plexuses. The left nerve applies itself to the anterior surface and lesser cur- 
vature of the stomach, to which it is distributed. It sends communicating offsets 
along the lesser curvature of the stomach to the right pneumogastric, and between 
the layers of the small omentum to the hepatic plexus. 
