﻿16 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL. 
  MUSEUM 
  vol. 
  67 
  

  

  were 
  both 
  forced 
  either 
  to 
  the 
  right 
  or 
  to 
  the 
  left. 
  This 
  center 
  is 
  

   not 
  precisely 
  the 
  anterior 
  one 
  of 
  the 
  three 
  segments 
  of 
  the 
  cranium 
  

   proper, 
  as 
  has 
  been 
  claimed, 
  10 
  but 
  the 
  "dead 
  center" 
  may 
  be 
  consid- 
  

   ered 
  as 
  passing 
  through 
  the 
  frontals 
  above 
  and 
  palatals 
  below. 
  

   Either 
  of 
  these 
  pairs 
  of 
  bones 
  may 
  vary 
  somewhat 
  in 
  accordance 
  with 
  

   the 
  portion 
  of 
  the 
  skull 
  either 
  craniad 
  or 
  caudad 
  thereto, 
  according 
  

   to 
  whether 
  the 
  more 
  powerful 
  influence 
  lies 
  in 
  one 
  direction 
  or 
  the 
  

   other. 
  In 
  the 
  four 
  skulls 
  examined 
  the 
  original 
  seat 
  of 
  injury 
  has 
  

   been 
  in 
  the 
  neighborhood 
  of 
  one 
  of 
  the 
  glenoid 
  fossae. 
  

  

  It 
  is 
  difficult, 
  if 
  not 
  impossible, 
  to 
  speculate 
  with 
  any 
  degree 
  of 
  

   certainty 
  upon 
  the 
  relative 
  development 
  of 
  the 
  temporals 
  and 
  mas- 
  

   seters, 
  considered 
  as 
  separate 
  muscles, 
  because 
  of 
  their 
  extreme 
  

   interdependence. 
  The 
  previous 
  condition 
  of 
  the 
  masseters 
  can 
  only 
  

   be 
  deduced 
  from 
  the 
  configuration 
  of 
  the 
  zygomatic 
  arch. 
  Reduc- 
  

   tion 
  in 
  the 
  size 
  of 
  one 
  temporal 
  muscle 
  is 
  not 
  necessarily 
  followed 
  by 
  

   a 
  smaller 
  zygomatic 
  arch, 
  and 
  therefore 
  by 
  inference, 
  a 
  smaller 
  mas- 
  

   seter 
  upon 
  that 
  side; 
  but 
  reduction, 
  for 
  any 
  reason, 
  of 
  the 
  size 
  of 
  

   the 
  arch 
  does 
  seem 
  to 
  result 
  in 
  a 
  lessened 
  volume 
  of 
  the 
  adjacent 
  

   temporal 
  muscle. 
  

  

  The 
  interrelationship 
  of 
  the 
  anterior 
  with 
  the 
  posterior 
  portion 
  of 
  

   the 
  temporal 
  muscle 
  is 
  somewhat 
  obscure, 
  but 
  fluctuations 
  in 
  the 
  size 
  

   of 
  this 
  muscle 
  are 
  not 
  necessarily 
  uniform 
  for 
  the 
  two 
  parts. 
  The 
  

   size 
  of 
  the 
  anterior 
  portion 
  of 
  the 
  temporal 
  fossa 
  — 
  lying 
  immediately 
  

   adjacent 
  to 
  the 
  supraorbital 
  processes 
  in 
  carnivores 
  — 
  may 
  be 
  very 
  

   much 
  larger, 
  indeed, 
  upon 
  one 
  side 
  when 
  the 
  posterior 
  portion 
  — 
  over- 
  

   lying 
  the 
  brain 
  case 
  proper 
  — 
  is 
  but 
  a 
  trifle 
  more 
  extensive 
  than 
  upon 
  

   the 
  opposite 
  side. 
  The 
  explanation 
  of 
  this 
  fact 
  is 
  believed 
  to 
  be 
  

   that 
  the 
  extreme 
  cranial 
  portion 
  of 
  the 
  temporal 
  muscle 
  is 
  the 
  part 
  

   that 
  is 
  used 
  in 
  contributing 
  the 
  ultimate 
  contracting 
  power 
  of 
  which 
  

   the 
  jaw 
  muscles 
  are 
  capable. 
  As 
  this 
  final 
  force 
  can 
  hardly 
  be 
  applied 
  

   upon 
  the 
  weaker 
  side 
  of 
  the 
  head, 
  because 
  of 
  pain 
  or 
  mechanical 
  

   disability, 
  nondevelopment 
  of 
  the 
  anterior 
  part 
  of 
  the 
  temporal 
  muscle 
  

   upon 
  that 
  side 
  of 
  the 
  cranium 
  results. 
  Certain 
  it 
  is 
  that 
  a 
  disparity 
  

   in 
  the 
  development 
  of 
  the 
  anterior, 
  as 
  compared 
  with 
  the 
  posterior, 
  

   part 
  of 
  an 
  abnormal 
  temporal 
  fossa 
  recurs 
  sufficiently 
  often 
  to 
  indi- 
  

   cate 
  a 
  substantial 
  difference 
  in 
  the 
  precise 
  functions 
  of 
  the 
  two 
  

   corresponding 
  portions 
  of 
  the 
  temporal 
  muscle. 
  

  

  The 
  pterygoid 
  plates 
  and 
  fossae 
  naturally 
  reflect 
  the 
  development 
  

   of 
  the 
  pterygoid 
  muscles, 
  and 
  a 
  smaller 
  plate 
  upon 
  one 
  side 
  means 
  

   that 
  the 
  muscles 
  attached 
  thereto 
  were 
  correspondingly 
  weaker. 
  

  

  Asymmetrical 
  development 
  of 
  the 
  rear 
  half 
  of 
  the 
  skull 
  — 
  at 
  least 
  

   of 
  the 
  superior 
  portion 
  — 
  is 
  closely 
  correlated 
  with 
  size 
  and 
  strength 
  

  

  ""Howell, 
  A. 
  B., 
  Individual 
  and 
  age 
  variation 
  in 
  Microtus 
  montanus 
  yosemite, 
  Journ, 
  Agric. 
  Research, 
  

   vol. 
  28, 
  1924, 
  pp. 
  977-1016. 
  

  

  