OF THE SPINAL CORD 147 



the two lowest nerves entering the brachial and 

 sacral plexuses respectively. 



The anatomy of the lumbo-sacral plexus makes it 

 easy to remember that the quadriceps and adductors 

 must be supplied from the lumbar nerves, whereas the 

 hamstrings and crural muscles are innervated from 

 the sciatic nerve. There is a general tendency for 

 flexors to derive their nerve supply from a level 

 slightly below that for the extensors. It is easy to 

 see why this should be the case if we glance at a 

 quadruped, where the flexors are posterior to the 

 extensors. 



THE EXACT DIAGNOSIS OF INJURIES OF THE 

 SPINAL CORD. 



The following lesions of the cord may be responsible 

 for symptoms of paralysis or anaesthesia after an 

 injury to the back. 



1. Simple concussion, the injuries being micro- 

 scopical or functional only, and the paralysis transient. 



2. Complete division of ah 1 the nervous elements. 



3. Pressure on the cord due to bone, callus, or a 

 foreign body, not causing a total transection. 



4. Haemorrhage into the spinal membranes. 



5. Haemorrhage into the cord itself. 



6. Later complications such as myelitis, traumatic 

 neurasthenia, etc. 



This is not the place to consider all these in their 

 surgical bearing. We want to look at them in 

 relation to the physiology of the spinal cord. 



A total transection of the cord in man, not in 

 animals, affects profoundly the functions of the 



