XXXl] SPINAL COED 235 



The area of small nerve fibres at the apex of the posterior 

 cornu, and extending a little laterally of the head is Lissauer's 

 tract. 



2. Compare the three sections and note 



a. General differences in the cord and the white 

 substance. 



The transverse area of the cord is largest in 

 the cervical swelling, and is larger in the lumbar region 

 than in the thoracic region. 



The transverse area of the white substance, 

 i.e. the number of nerve fibres, is greater in the cervical 

 than in the thoracic region, and greater in the thoracic 

 than in the lumbar region. (The latter difference may 

 not be easily appreciable by the eye.) 



Outline. The side to side diameter is larger than 

 the antero-posterior in the cervical swelling; this is 

 much less the case in the lumbar swelling, and the 

 diameters are nearly equal in the thoracic region. 



The central canal is nearer the ventral than the 

 dorsal surface (rather more than ird way from the 

 ventral surface) in the cervical swelling and thoracic 

 region ; it is about the middle of the section in the 

 lumbar swelling. * 



Division of posterior column. In the cervical 

 region the posterior column is divided into two parts, 

 G-olPs column (funiculus gracilis, median posterior 

 column) near the posterior fissure, and Burdach's 

 column (funiculus cuneatus, postero-lateral column) 

 near the posterior cornu and posterior roots. 



In the mid-thoracic region the division is still 

 seen, though not always distinctly ; it is not present in 

 the lumbar region. The two columns may be made 



