246 



PHYSIOLOGY 



CHAP. 



seen in Fig. 106, taken from a classic work by Frankenhauser 

 (1867), the sympathetic nerves running towards the uterus 

 originate in the aortic plexus : they receive numerous fibres from 

 the solar ganglion, the renal ganglia, the two genital ganglia and 

 the lumbar ganglia of the sympathetic chain ; at the level of the 

 point of origin of the lower mesenteric artery they unite in a 

 wide nervous plexus beset with ganglia called the great uterine 

 plexus. Near the sacral promontory, this plexus divides into 

 the two hypogastric plexuses, which surround the rectum, and 

 make their way partly to the lateral margins of the uterus, partly 

 to the ganglia of the cervix uteri ; these form two wide plexuses 

 situated at the upper part of the cervix of the uterus, and send 

 branches to a great part of the uterus. The Fallopian tubes and 

 the ovaries receive sympathetic fibres from the renal and genital 

 ganglia, associated with the spermatic vessels. 



The nerve-fibres of cerebro-spinal origin reach the uterus by 

 different paths : by way of the aortic plexus, the vagus, the phrenic 



Minucan 



FIG. 105. Normal curve of the uterine contractions during the period of dilatation ; recorded 

 by means of tocodynamometer. (Schatz, Arch, fiir Gyn. iii.) 



and the splanchnics ; from the lumbar spinal cord by means of 

 the rami communicantes ; finally, from the sacral plexus run many 

 branches which join the cervical ganglia and go direct to the 

 uterus. 



Experiments made on animals to determine the function of 

 these various nerves have not led to any concordant results. 

 It is only certain that important motor centres for the uterus 

 exist in the medulla oblongata, the lumbar portion of the spinal 

 cord and the great uterine plexus. The sensory nerves appear to 

 pass chiefly by way of the sacral plexus. It is extremely probable 

 that the central elements of the ganglia of the great uterine 

 plexus, the cervical ganglia and the more peripheral ganglia 

 found in the walls of the uterus itself act as reflex or automatic 

 centres for the regulation of the uterine contractions. It has, 

 in fact, been proved that the activity of the uterus which develops 

 during parturition may persist regularly in the bitch even after 

 transverse section of the spinal cord at the level of the last dorsal 

 vertebra (Goltz). It may therefore be concluded that the lumbar 

 swelling of the spinal cord contains a regulating centre for the 



