MAUTHNER’S CELL 9] 
THE NUCLEUS MOTORIUS TEGMENTI 
The term nucleus motorius tegmenti is here used to designate 
the column of cells which lies in the ventro-medial region of the 
- medulla oblongata and is identical with the bulbar portion of 
this nucleus as defined by Edinger. It extends throughout the 
medulla oblongata and, with the abducent nucleus, constitutes 
the somatic motor column of the bulb. The following account 
is not intended to be complete but aims merely to present certain 
facts concerning the character of the cells, their grouping and 
the functional connections of the groups, in order that the rela- 
tions of the cells of Mauthner and Miiller to the nucleus may 
be clearly discussed. ‘These giant cells are highly differentiated, 
but none the less integral members of the nucleus, which for the 
sake of clearness are discussed separately. 
The extent and subdivisions of the nucleus may be seen in 
the horizontal projection drawn in figure 2, where it is indicated 
by the double cross-hatching. It will be noted that the fourrostral 
groups (P.Supa., P.Sup., P.Pre. M., P.Post M.) are roughly co- 
extensive with the motor Vth nucleus; the caudal end of the pars 
postmauthnerea (P.Post M.)anda small group whichis not indicated 
are similarly related to the two small VIthnuclei; the pars interme- 
dia (P. Int.) and the pars inferior (N.Mot.Teg.Inf.), coincide less 
obviously withthe motor VIIth and nucleusambiguusrespectively. 
This chart is based upon projections of the adult brain; in larvae 
the groups are more widely separated and their relations to the 
motor nuclei are more clearly marked. The latter relation is no 
doubt the primitive one, i.e., the nucleus serves to codrdinate the 
activities of the motor nuclei of the brain and cord. Secondarily 
other connections have been established with primary sensory 
centers of the oblongata and these connections are physiologically 
the more important ones, as will be seen below. 
The position of the nucleus in the cross section is shown in fig- 
ure 4 at P.Post M. and in figure 5 at N.mot.tegm., where it is seen 
to be made up of cells of various sizes ranging from those just 
visible at the magnification of 40 diameters to the great Mauth- 
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