DISSECTION OF THE HEAD AND NECK 245 



missure (commissura grisea anterior] and behind it the posterior 

 gray commissure ( commissura grisea posterior) . Study in cross- 

 section each of the following gray columns (columnae griseae) : 



(a) Anterior column of gray matter (columna anterior) (0. T. anterior 

 horn). 



(6) Lateral column of gray matter (columna lateralis) (0. T. lateral 



horn). 

 (ba) Reticular formation (formatio reticularis) . 



FIG. 102. 



.l.d. 



F.m.v. 



5.U. 



N. Spinalis 

 R.y. 



Schematic representation of the portion of a spinal cord corresponding to the attachment of the 

 ventral and dorsal roots of one pair of spinal nerves. (From Barker, The Nerv. Syst., New York, 1901, 

 PI. II. Fig. 2.) 



Black. Cc., canalis centralis; C.d., commissura posterior (O.Y., commissura dorsalis) ; C.d.g., 

 columna posterior (O.Y.,cornudorsalegriseum) ; C.v.g., columna anterior (O.Y.,cornuventralegriseum); 

 Cm.v.a., commissura anterior alba (O.Y., com. ventralis alba) ; Cm.v.g., commissura anterior grisea (O.Y. 

 com. ventralis grisea) ; Fc., funiculus cuneatus; Fg., funiculus gracilis; Fd., funiculus posterior (O.Y. 

 funiculus dorsalis); FL, funiculus lateralis; Fv., funiculus anterior (O.Y., fun. ventralis); F.m.v., 

 fissura mediana anterior (O.Y., fis. med. ventralis) ; G.sp., ganglion spinale ; R.d., radix posterior nervi 

 spinalis (O.Y., rad. dorsalis) ; E.v., radix anterior (O.Y., ventralis) nervi spinalis (O.Y., rad. ventralis) ; 

 S.I d., sulcus lateralis posterior (O.Y., sulc. lat. dorsalis) ; S.l.v., sulcus lateralis anterior (O.Y., sulc. lat. 

 ventralis) ; S.i.d., sulcus intermedius posterior (O.Y., sulc. intermed. dorsalis) ; S.m.d., sulcus medianus 

 posterior (O.Y., sulc. med. dorsalis.) 



Red. Peripheral sensory neurones. The cell-bodies, 1, are situated in the spinal ganglion. The 

 peripheral processes enter the peripheral nerves, the central axones pass by way of the radix posterior 

 into the funiculus cuneatus of each side. There each axone bifurcates into an ascending and a 

 descending limb, giving off also collaterals to the gray substance. 



Blue. Lower motor neurones. The cell-bodies, 1, are situated in the columnae anteriores. They 

 send their axones by way of the anterior roots into the peripheral nerves. 



The neural mechanism believed to form the basis of the simplest reflex arc is illustrated in the 

 figure. 



(c) Posterior column of gray matter (columna posterior) (0. T. posterior 

 horn). 



(ca) Neck of posterior column (cervix columnae posterioris) . 



(cb) Apex of posterior column (apex columnae posterioris). 



