350 PRACTICAL PHYSIOLOGY 



The cervical sympathetic fibres pass through the ganglion, and have 

 their cell-stations in the superior cervical sympathetic ganglion. 



Excitation of the (1) cervical sympathetic dilates the pupil, retracts 

 the nictitating membrane, causes separation of pupils and projects the 

 eye with the axis of the eyeball straight forwards. 



FIG. 231. Arterial pressure. Effect of exciting the stellate ganglion (accelerator 

 nerves). The time is marked in seconds. (L.H.) 



It constricts the blood-vessels of the skin, glands, and mucous 

 membrane of the head. 



It dilates the vessels in the bucco-facial region of the dog. 



It excites secretions of the glands of the head, both salivary and 

 sweat glands. 



vN/^^^ 



3"-D 



FIG. 232. Record of arterial pressure. Cardiac acceleration produced by excita- 

 tion of the third dorsal root during the time shown by the signal line. (Bradford.) 

 The time is marked in seconds. 



It erects the hairs in the cat and monkey over certain regions of 

 the face and scalp. 



(2) The depressor nerve is an afferent nerve which runs from the 

 heart to the spinal bulb, and causes general dilatation of the blood- 

 vessels especially in the splanchnic region. (See Fig. 112.) 



It thus lowers the arterial pressure. The depressor is bound up 

 with the vagus in the dog. 



