528 COMMENCEMENT OF THE SYMPATHETIC NERVE. 



the external edge of the foot, about the posterior end of the 

 metacarpal bones, it divides into three branches. One pro- 

 ceeds to the outside of the little toe ; another passes to the 

 angle between the fourth toe and the little toe, and divides into 

 branches which are distributed to the corresponding sides of these 

 toes. The third branch proceeds more deeply in the foot, from 

 the external towards the infernal edge of it, and is spent upon 

 the deep-seated contiguous muscles. 



The Great Sympathetic or Intercostal Nerve. 



The great sympathetic system is characterised by the 

 greyish color and the softness of its nerves, and the gangli- 

 form enlargements found upon them in various situations, con- 

 nected together by intervening cords or nervous filaments. 

 These ganglia are found in the head, neck, thorax and abdo- 

 men. Many of them are placed about the viscera and along 

 the course of the blood-vessels of the trunk and head, having 

 intercurrent branches, so as to form large centres or plexuses, 

 from which nerves are distributed to the neighboring organs. 

 A ganglionated cord composed of a large number of ganglia 

 and intercurrent trunks, is formed in a line between the head 

 and os coccygis, on either side of the spinal column, for the 

 double purpose of its interchanging filaments with the spinal 

 nerves as they leave the intervertebral foramina, and commu- 

 nicating with the sympathetic nervous plexuses placed over the 

 middle portion of the spine. It communicates with the cerebral 

 nerves in like manner, at their exit from the cranium, with the 

 exception of the fourth and sixth, with which it forms junctions 

 in the cavernous sinus, and the auditory, optic, and olfactory, 

 with which it is connected at the places of their final distribution. 

 Although this system does not send out branches as distinct 

 nervous trunks to the extremities, it nevertheless gives fila- 

 ments to all the spinal nerves, among the rest those that form 

 the cervical, lumbar, and sciatic plexuses, and which they 

 accompany in their distribution. The filaments which go to 

 the extremities form, however, but a minute portion of this 

 extensive system. They are not the agents of cerebral sensa- 



