J   (2)  Lateral  groups  in  the
i      oeiviciil  and  lumbar  en-

i.     laigeiueuts.
Presiding  over  flexion  and
extension  of  the  limbs
(possessed  by  all  verte-
brates).
f  Cells  of  the
axtekiok
Horn.
THE  GRAY      |

MATTER  OF  J

THE  CORD.     1


Cells  OF  THE
Cextr.vl

(tKAY

Matter.
Cells  of  the
Posterior

HORN'S.
,,,    ,,.,,,  r iio      f Presiding     over     move-

(1     Middle  group  oiciiWs  nients  of  the  hand  and

(2)  Cenlral  group  of  cells  J  fl„gers(  peculiar  to  man)
in  the  cervical  and  lum-  ^  ^^J  ^^^^  ^ct  of  walking
bar  enlargements.  I     erect.
Motor  cells,  whose  peculiar  functions  are  not  deter-
mined.
Trophic  centres  for  the  motor  nerves  and  the  muscles
supplied  by  them.
Motor  incchnnixtn  necessary  to  spinal  automatism  and
reflex  spinal  action.
Anterior  part.      Trophic  centres  for  the  skeleton.
r  (1)  Trophic    centres    for    the    skin,
Posterior  part.  \       nails,  bladder,  joints.
L  (2)  Vaso-inotor  centres.
Automatic  centres  of  a  complex  nature,  and  the  asso-
ciating fibres  necessary  to  their  peculiar  functions
(sexual,  vesical,  rectal,  cilio-spinal,  etc).
Trophic  centres  for  sensory  conducting-tracts.
Paths  of  conduction  of  sensations  of  pain,  and  tem-
perature from  all  parts  below.
Clarke's  column  of  cells  (vesicular  column)  which  are
apparently  associated  with  the  fibres  of  the  "direct
cerebellar  column.''

Posterior  group  of  cells ;  related  to  sensations  of  all
kinds.
The  sensory  mechanism  necessary  to  spinal  automatism
and  spinal  reflex  action.
The  size  of  the  multipolar  cells  of  the  anterior  horns  seems  to  depend  upon  two  factors :
(1)  the  size  of  the  muscle  supplied  by  the  cell,  and  (2)  the  length  of  the  nerve-fibre  which
connects  the  cell  with  the  muscle  (Spitzka).
