THORAX AND ABDOMEN OF THE HORSE 



9 



the pectoral muscles. The second to the eighth furnish branches to the 

 transverse thoracic muscle. The seventh to the seventeenth pass beyond 

 the costal arch and are found during the dissection of the wall of the 

 abdomen between the transverse and internal oblique muscles. They 

 end in the rectus abdominis muscle. Small branches are supplied to 

 the diaphragm by the intercostal nerves from the eighth to the last. 

 At a distance from the vertebral column that becomes greater with 



Dorsal root. 



Spinal ganglion. 



Mixed spinal nerve. 

 Dorsal ramus. 



Dorsal cutaneous nerve. 



Ventral root. 

 Recurrent nerve 



Sympathetic ganglion. 

 Ramus communicans 



Ventral ramus. 



Lateral cutaneous nerve. 



Fig. 4. — Diagram of a typical Thoracic Nerve. 



each succeeding nerve, the intercostal nerves (with the exception of the 

 first) give off a large lateral cutaneous branch (ramus cutaneus 

 lateralis), which passes down the intercostal space between the external 

 and internal intercostal muscles. The earlier lateral cutaneous rami 

 pierce the external intercostal and end in the ventral serratus and 

 latissimus dorsi muscles and the skin, and one or two of them are 

 connected with the caudal pectoral nerves. The middle members of 

 the series of cutaneous branches pierce the external intercostal muscles 

 close to the attachment of the digitations of the external oblique ab- 



