SPINAL ACCESSORY NERVE 773 



they take origin) cervical and tlioracic, and form altogetlier three or four pairs of 

 nerves. Tliese all proceed to the deep cardiac plexus, witli one exception, the 

 inferior cervical cardiac of the left side, which joins the superficial cardiac plexus. 



(i) The superior cervical cardiac nerves, one or two in nundjer, join the 

 corresponding branches from the sym])athetic. A full account of these nerves will 

 l)e given in the description of the cardiac plexus. (See Sympathetic System.) 



(ii) The inferior cervical cardiac nerve of the left side passes downwards 

 on the left side of the aortic arch between the latter and the ]>leura, ;ind joins the 

 superficial cardiac plexus. As it crosses the arch the phrenic nerve is in front of 

 it, and the left uj)])er cervical cardiac of the synipathetic is behind it. The right 

 inferior cervical cardiac |)asses downwards on the side of the trachea to join the 

 deep cardiac plexus. 



(iii) The thoracic cardiac branches usually arise close to and in connection 

 with the recurrent laryngeal nerves; consequently the nerves on the left side arise a 

 little lower than the right. They are directed inwards to the front of the lower end 

 of the trachea to terminate in the dee]) cardiac plexus. 



(f/) The anterior pulmonary branches are one or two small twigs, which arise 

 at the ui)per l)order of tlie root of the lung and pass forwards to gain the anterior 

 aspect of the bronchus, where they connnunicate with the synipathetic and form 

 the anterior pulmonary plexus, whence fine twigs pass along the })ronchus into 

 the lung. 



The posterior pulmonary plexus is formed by a great flattened expansion of 

 the pneumogastric nerve on the posterior aspect of the bronchus. From this several 

 stout twigs proceed, which communicate with twigs from the second, third, and 

 fovirth thoracic ganglia of the sympathetic, and pass into the lung, and it anasto- 

 moses witli the corres})onding plexus of the opposite side. 



(//) QEsophageal branches. — Numerous twigs are given off from the plexus 

 gula; as it encircles the (esophagus, and are distributed to the muscuhir and mucous 

 coats of that canal. 



(/) Abdominal branches. — The termination of the left vagus nerve passes 

 through tlie u'so])liageal oi)ening in the diaphragm on the anterior asi)ect of the 

 (I'sophagus, and is distributed over the anterior surface of the stomach. The 

 strongest branches accompany the coronary artery along the lesser curvature of 

 the stomach, and, from these, twigs pass on to the hepatic artery and join the 

 hepatic plexus. The termination of the right vagus is distributed upon the pos- 

 terior surface of the stomach, and gives twigs to the coeliac, splenic, and left renal 

 plexuses. 



ELEVENTH OR SPINAL ACCESSORY NERVE 



The spinal accessory nerve consists of two distinct parts, which are usually 

 known as the; s})inal and the accessory portions of the nerve. The former of these 

 (spinal portion) is a purely motor nerve which arises from the nerve-cells in the 

 ventro-lateral group of the anterior cornu of the cervical portion of the spinal cord. 

 The accessory portion, on the other hand, arises by a series of roots from the distal 

 parts of both the motor and sensory accessorio-vago-glosso-pharvngeal nuclei in the 

 medulla, and would l)e more properly described as the most distal vagal roots 

 (Obersteiner) than as a s('))arate nerve. 



The accessory portion (distal vagal roots, or bulbar accessory) consists of four 

 or five fasciculi which arise in a precisely similar manner to the roots of the vagus 

 with which they are in series. Shortly after their emergence from the medulla 

 they join the s})inal portion and accompany the latter through the jugular foramen. 

 Having gained the exterior of the skull, the bull)ar accessory leaves the nerve 

 with wdiich it has been associated in part of its course, and joins the ganglion of 

 the root of the vagus; some of its fibres pass into the ])haryngc:d and su])erior 

 laryngeal nerves as already descril)ed. 



The spinal portion arises from the ventro-lateral group of nerve-cells in the 

 anterior cornu of the cn^rvical })ortion of the si)inal cord. Some of the fibres run 

 longitudinally for a short distance and join other more direct fibres, which arch 

 backwards and outwards to emerge from the lateral colunm of the cord between the 



