CEPHALIC PORTION OF THE SYMPATHETIC SYSTEM. 



515 



Sympathetic System. 



The symiKithetic or ganglionic system of nerves, the nerves of 

 organic life, consists of two large cords or chains of nerves, which 

 extend from the head to the posterior extremity of the sacrum, 

 under the lateral parts of the bodies of the vertebras, on each side 

 of the column. These nerve cords are furnished Avith a number 

 of ganglia, •svhich both give and receive numerous communicating 

 filaments from the cerebro-spinal nerves. 



A sympathetic ganglion is a nerve centre, to which converge 

 various so-called (cferent branches, motor, sensory, and sympa- 

 thetic, while the filaments which leave the ganglion to supply 

 the various organs, are known as the emergent branches, which 

 thus exercise a mixed and varied function. 



Fig. 194.. 

 Dorsal gauglioii of sympathetic nerve from a Mouse, a, b, Connect- 

 ing cords to adjacent ganglia ; ccc, Efferent and spinal nerve branches ; 

 il, Ganglionic cells ; e, Nerve fibres crossing the ganglion. 



The sympathetic nerves chiefly supply the blood-vessels (round 

 which they twine in a complex manner), the glands, and the 

 viscera. 



For the convenience of description, the sympathetic system may 

 be divided into five regions — viz., the cephalic, cervical, dorsal 

 or thoracic, lumbar or abdominal, and sacral or pelvic. 



cephalic P<)RTI(3N of THE SYMPATHETIC SYSTEM. 



The cephalic portion consists chiefly of the ophthalmic or 

 lenticular, spheno-iKilatine or Meckel's, and the otic ganglia. 

 The Lenticular ganglion is situated between the optic 



