1028 



THE NERVE SYSTEM 



The left phrenic nerve is rather longer than the right, from the inclination of 

 the heart to the left side, and from the Diaphragm being lower on this than on the 

 opposite side. It enters the thorax behind the left innominate vein, and crosses 

 in front of the vagus and the arch of the aorta and the root of the lung. 



Each nerve supplies filaments to the pericardium and pleura, and near the 

 thorax is joined by a filament from the sympathetic, and, occasionally, by one 

 from the ansa hypoglossi. Branches have been described as passing to the peri- 

 toneum. 



MUSCULOCUTANEOUS 



INTERCOSTO- HUMERAL 

 NERVES 



LONG SUBSCAPULAR 

 NERVE 



SUBSCAPULAR 

 NERVES 



LATERAL CUTA- 

 NEOUS BRANCH 

 OF FOURTH 

 INTERCOSTAL 



LATERAL CUTANEOUS 



BRANCH OF 



THIRD INTERCOSTAL 



LONG THORACIC 

 NERVE 



FIG. 758. The right brachial plexus (infraclavicular portion) in the axillary fossa, viewed from below and 

 in front. The Pectoralis major and minor muscles have been in large part removed; their attachments have 

 been reflected. (Spalteholz.) 



From the right nerve one or two filaments pass to join in a small ganglion with 

 phrenic branches of the solar plexus; and branches from this ganglion- are dis- 

 tributed to the hepatic plexus, the suprarenal gland, and inferior vena ca'va. From 

 'ihe left nerve filaments pass to join the phrenic plexus of the sympathetic, but 

 without any ganglionic enlargement. 



Applied Anatomy. Irritation of the phrenic nerve causes hiccough and persistent cough. 

 Bilateral paralysis of the phrenic causes death from paralysis of the Diaphragm. This form of 

 death is seen by the surgeon in fracture dislocation of the third cervical vertebra. Division of 

 the phrenic on one side is not fatal, and is occasionally practised by the surgeon in removing 

 a tumor of the neck. In Hearn's and Franklin's cases of removal of the vagus the phrenic 

 was also divided. Unilateral division of the phrenic nerve causes paralysis of the corresponding 

 half of the Diaphragm, which is difficult of recognition, because, as Gowers points out, the 

 patient can still take deep inspirations, the thoracic muscles not being paralyzed. 



The Deep Branches of the Cervical Plexus. External Series. Communi- 

 cating Branches. The deep branches of the external series of the cervical plexus 



