862 THE NERVES. 



from the sixth cervical pair ; the other from the seventh, and always traversing 

 the last fasciculus of the superior scalenus before joining the first. The single 

 branch resulting from the union of these two roots is thin and very wide. It 

 passes back to the surface of the serratus magnus, crossing the direction of its 

 fibres, and is expended in its substance, sending regularly arranged ramifications 

 upwards and downwards. 



This is the respiratory nerve of Bell. 



4. Pectoeal, or Inferior Thoracic Branckes. 



Five principal are distinguished : — 



1. One emanating from the sixth and seventh cervical pairs — particularly the 

 former — and passing to the internal face of the anterior deep pectoral muscle, 

 to ramify exclusively among its fibres, after dividing into two branches : an 

 anterior, short and thick, and a posterior, long and slender (Fig. 465, 10). 



2. A second branch, arising from the anterior brachial and cubito-plantar 

 (or median) nerves, by two roots, which join in forming an arch beneath the 

 axillary artery. 



It passes between the anterior and posterior deep pectoral muscles, and 

 terminates in the superficial one, after furnishing some ramuscules to the 

 posterior deep pectoral by means of a long thin filament, which is carried back 

 to the external surface of that muscle (Fig. 465, 11). 



3. The other three, passing to the posterior deep pectoral muscle, generally 

 come from the trunk that constitutes the subcutaneous thoracic branch. Com- 

 prised between the serratus magnus and posterior deep pectoral, they are 

 directed downward and backward, and enter the latter muscle. One of them — 

 longer and thicker than the other — follows the course of the spur vein. 



5. Subcutaneous Thoracic Branch (Fig. 465, 9). 



This is a very remarkable nerve, arising from the brachial plexus by a trunk 

 common to it and the ulnar nerve. Placed at first to the inside of that nerve, 

 it soon leaves it to pass backward to the internal face of the caput magnum and 

 the panniculus carnosus. In its long com'se, it acts as a satellite to the spur 

 vein, above which it is situated. It may be followed to the flank, where its 

 terminal divisions are lost in the substance of the panniculus muscle. Those it 

 gives off are also destined to that muscle ; they anastomose with the majority of 

 the perforating intercostal nerves, forming an elaborate network on the inner 

 face of the panniculus. 



One of its branches, along with a voluminous perforating nerve, bends round 

 the inferior border of the latissimus dorsi, and passes forward to enter the 

 scapulo-humeral portion of the panniculus. 



6. Latissimus Dorsi Branch (Fig. 465, 6). 



Formed of fibres, the larger portion of which come from the eighth cervical 

 pair, this branch proceeds backwards and upwards to the internal face of the 

 latissimus dorsi, and is soon expended in that muscle. It is long and thick. 



7. Circumflex or Axillary Nerve (Fig. 465, 13). 



Somewhat considerable in voliune, this nerve is furnished directly by the 

 eighth cervical pair. It passes backward and do^vnwa^d on the internal face of 



