164 CERVICAL NERVES. 



The superior laryngeal^^ arises from the ganglionic plexus, enters 

 the larynx, and is distributed to its mucous membrane. The^ cardiac 

 branches*^ are two or three in number, and descend to join the 

 cardiac plexus. The inferior laryngeal^^"^ or recurrent laryngeal^ 

 curves around the aorta upon the left side, and the subclavian upon 

 the right ; ascending between the trachea and oesophagus, it is dis- 

 tributed to the muscles of the larynx, communicating with the supe- 

 rior laryngeal and sympathetic nerve. Anterior and posterior^^ *9 

 pulmonary branches are given off in the thorax to form the pulmo- 

 nary plexus. The (Esophageal hranches'^^ surround the oesophagus, 

 and with it enter the abdomen through the diaphragm, there to be 

 spent upon the stomach and neighbouring viscera, and also com- 

 municating with the solar plexus. 



Spinal accessory. — This branch^ of the eighth pair escapes also at 

 the jugular foramen, and divides into two branches, one of which 

 gives filaments to the superior pharyngeal nerve; the other, which is 

 the larger, descends obliquely backwards, and piercing the sterno- 

 mastoid muscle, is distributed to the trapezius, after having commu- 

 nicated with the upper cervical nerves.^ ^^ 



9th. The hypoglossal nerve emerges from the cranium through 

 the anterior condyloid foramen, it then passes between the internal 

 carotid artery and internal jugular vein, and curving around the 

 occipital artery, sends branches to the muscles of the tongue. The 

 desce7idens noni descends as a long, thin filament, in front of the 

 sheath of the vessels, and below the middle of the neck ; forming a 

 loop with a branch from the second and third cervical nerves ; it 

 communicates with the pneumogastric and sympathetic. 



SPINAL NERVES. 



After the union of the anterior or motor root with the posterior or 

 sensitive root in the intervertebral foramen, the spinal nerves divide 

 into two trunks, the posterior of which are much the smaller, and sup- 

 ply the muscles of the back ; the anterior are large, and communi- 

 cating with the ganglions of the sympathetic nerve, form plexuses 

 which give off the principal nerves to the muscles of the trunk and 

 extremities. 



CERVICAL NERVES. 



These are eight in number : the first is called the sub-occipital; it 

 passes out of the spinal canal between the occiput and atlas. 



2Viree superior cervical nerves anastomose freely and form a 

 cervical plexus^ which sends numerous branches to the muscles and 

 skin of the neck, forming communications with the ninth and facial 

 nerves. The p)hrenic nerve*' is formed by filaments of the cervical 

 plexus, and passing over the scalenus anticus muscle, and through 



