216 The Spinal Cord 



in the medulla above the level of the crossing in the pyramids, loss 

 of motion as well as of sensation occurs upon the opposite side of the 

 body. 



Total transverse lesions involve, of course, complete loss of 

 motion and sensation on both sides below, and, the sensory nerves in 

 the proximal part of the cord, close to the lesion, being in distress, cir- 

 cumferential localised pains, ' girdle pains,' as they are called, result. 

 The area of the girdle-pains indicates which nerves are crossing in the 

 cord immediately above the damage, and points out the exact situa- 

 tion of the lesion. The girdle-pains which come on immediately after 

 a fracture of the spine are due to the pressure of the displaced verte- 

 bra upon the nerves which run almost vertically along the side of the 

 cord. The pains are referred by nerves which actually arise from the 

 cord at the level of at least one vertebra higher than that which is 

 displaced. 



The region of the umbilicus is supplied by the tenth dorsal, and 

 the ensiform area by the sixth and seventh. 



In complete transverse lesion of the middle of the lumbar enlarge- 

 ment the elements of the sacral plexus may be dissociated from 

 central control, whilst those of the lumbar are not interfered with. 

 Thus there may be anaesthesia along the outer side of the leg (from 

 external popliteal nerve) with hypera^sthesia along the inner (internal 

 saphenous of anterior crural). When the lower part of the cervical 

 enlargement is traversed there is anaesthesia over the whole of the 

 chest, and, on account of the implication of the fibres of the ulnar 

 nerve, there is numbness along the little finger (p. 253). If the cord be 

 seriously damaged by disease or injury at the level of the third and 

 fourth lumbar nerves, the anterior crural, obturator, and great sciatic 

 convey no stimulus, so that the quadriceps extensor, adductors, ham- 

 strings, and muscles of leg and foot are paralysed, whilst there is loss 

 of sensation in the thigh (except in area of distribution of the external 

 cutaneous), leg, and foot. The sphincter ani also ceases to act. 



The reflexes in all these cases are altered ; most likely they are 

 exaggerated, for no cerebral control can reach the affected segment. 



Priapism often follows fracture above the lumbar enlargement, 

 because, the cerebral control being lost, the reflex is exaggerated 

 and is in constant action. If the bladder be paralysed, the urine is 

 retained and undergoes decomposition, cystitis is the result, and, unless 

 the greatest care and cleanliness be observed, bed-sores occur. 



If the lesion be at the level of the seventh dorsal, there will, in addi- 

 tion, be paralysis of the abdominal and lower intercostal muscles, the 

 area of insensibility reaching up to the level of the ensiform cartilage. 



If at the level of \hzfirst dorsal nerve (seventh cervical vertebra) 

 all the intercostals cease to move, and the muscles and skin supplied 

 by that part of the first dorsal which enters the inner cord of the 

 brachial plexus are paralysed, the skin over the whole of the thorax, 



