DISSECTING MANUAL. 



scapulae and the Rhomboidei, major and minor. The long 

 thoracic descends on the outer surface of and supplies the 

 Serratus magnus. The external anterior thoracic descends 

 on the outer side, and the internal interior thoracic on the 

 inner side, of the axillary artery, across which they commu- 

 nicate; they supply the Pectorales, major and minor. The 

 long subscapular accompanies the subscapular artery and 

 supplies the Latissimus dorsi. [622] 



Thoracic Nerves. There are twelve on each side, each 

 emerging below its corresponding vertebra and conforming, 

 with certain exceptions, to the typical spinal nerve. [635] 



The typical spinal nerve has two roots, dorsal and ventral; 

 the dorsal root, the larger, develops a spinal ganglion in the 

 intervertebral foramen (within the canal, for the sacral and 

 coccygeal ganglia) . Both roots unite in the foramen, forming 

 a spinal nerve which gives off a minute recurrent branch to the 

 spinal canal; it then divides into two primary divisions, an- 

 terior and posterior, before leaving the foramen. The posterior 

 division usually divides into two trunks, internal and external. 

 The internal trunks are cutaneous, and the external muscular 

 in the upper half of the body ; the opposite is the case in the 

 lower part. The cutaneous branches run inward and back- 

 ward in the upper half of the body, downward and outward in 

 the lower half. The anterior division receives, near its origin, 

 a gray ramus communicans from the sympathetic gangliated 

 cord and usually sends a white ramus communicans to it. A 

 thoracic nerve (to be regarded as a type) then runs in an in- 

 tercostal space, between the Intercostals, to the sternum, then 

 pierces the pectoral muscles, and, as the anterior terminal 

 cutaneous branch, supplies the skin. In its course the nerve 

 supplies the Intercostals and, at the side of the chest, gives 

 off a lateral cutaneous branch which pierces the External in- 

 tercostal and divides into two trunks, anterior and posterior, 

 running forward and backward. [608, 610, 615, 635] 



Anterior Divisions of Thoracic Nerves. Of the twelve, the 



[122] 



