126 HUMAN PHYSIOLOGY. 



1. Cilio-spinal centre, situated in the cord between the lower cervical 

 and .third dorsal vertebra. It is connected with the dilatation of the pupil 

 through fibres which emerge in this region and enter the cervical sympa- 

 thetic. Stimulation of the cord in this locality causes dilatation of the pupil 

 on the same side ; destruction of the cord is followed by contraction of the 

 pupil. 



2. Genito-spinal centre, situated in the lower part of the cord. This is 

 a complex centre and comprises a series of subordinate centres for the con- 

 trol of the muscular movements involved in the acts of defecation, micturi- 

 tion, ejaculation of semen, the movements of the uterus during parturition, 

 etc. 



3. Vasomotor centres, giving origin to both vaso-constrictor and vaso- 

 dilator fibres, which are distributed throughout the cord. Though acting 

 reflexly they are under the dominating influence of the centre in the me- 

 dulla. 



4. Sweat centres are also present in various parts of the cord. 

 Paralysis from Injuries of the Spinal Cord. 



Seat of Lesion. If it be in the lower phrt of the sacral canal, there is 

 paralysis of the compressor urethrse, accelerator urinre, and sphincter ani 

 muscles ; no paralysis of the muscles of the leg. 



At the upper limit of the sacral region. Paralysis of the muscles of 

 the bladder, rectum and anus ; loss of sensation and motion in the muscles 

 of the legs, except those supplied by the anterior crural and obturator, 

 viz. : psoas iliacus, Sartorius, pectineus, adductor longus, magnus and 

 brevis, obturator, vastus externus and internus, etc. 



At the upper limit of the lumbar region. Sensation and motion para- 

 lyzed in both legs; loss of power over the rectum and bladder; paralysis 

 of the muscular walls of the abdomen interfering with expiratory move- 

 ments. 



At the lower portion of the cervical region. Paralysis of the legs, etc. 

 as above; in addition, paralysis of all the intercostal muscles and conse- 

 quent interference with respiratory movements ; paralysis of muscles of 

 the upper extremities, except those of the shoulders. 



Above the middle of the cervical region. In addition to the preceding, 

 difficulty of deglutition and vocalization, contraction of the pupils, paralysis 

 of the diaphragm, scalene muscles, intercostals, and many of the accessory 

 respiratory muscles ; death resulting immediately, from arrest of respiratory 

 movements. 



