﻿132 
  ON 
  THE 
  VISCERAL. 
  ANATOMY 
  

  

  the 
  mouths 
  of 
  the 
  left 
  and 
  right 
  aortae, 
  "which 
  therefore 
  convey 
  pure 
  

   blood 
  that 
  has 
  passed 
  through 
  the 
  pulmonary 
  circulation. 
  But 
  the 
  

   pulmonary 
  artery, 
  which 
  is 
  shut 
  out 
  from 
  any 
  communication 
  with 
  

   the 
  left 
  ventricle 
  by 
  its 
  origin 
  in 
  front 
  of 
  the 
  column, 
  conveys 
  only 
  

   that 
  blood 
  which 
  was 
  in 
  the 
  anterior 
  portion 
  of 
  the 
  right 
  ventricle? 
  

   and 
  derived 
  from 
  the 
  right 
  auricle. 
  The 
  left 
  auricle 
  is 
  about 
  one 
  half 
  

   the 
  size 
  of 
  the 
  right 
  ; 
  the 
  septum 
  between 
  the 
  two 
  auricles 
  is 
  mem- 
  

   branous 
  and 
  perfect, 
  so 
  that 
  no 
  communication 
  exists 
  between 
  them. 
  

   One 
  large 
  pulmonary 
  vein 
  opens 
  into 
  this 
  auricle, 
  conveying 
  the 
  blood 
  

   from 
  both 
  lungs. 
  Below 
  is 
  the 
  opening 
  that 
  leads 
  into 
  the 
  left 
  ven- 
  

   tricle 
  ; 
  this 
  ventricle 
  is 
  many 
  times 
  thicker 
  than 
  the 
  right, 
  and 
  appears 
  

   to 
  have 
  less 
  than 
  a 
  third 
  the 
  capacity. 
  At 
  the 
  upper, 
  posterior 
  cor- 
  

   ner, 
  and 
  in 
  the 
  septum 
  ventriculorum, 
  is 
  the 
  orifice 
  of 
  that 
  passage 
  

   already 
  described, 
  as 
  establishing 
  a 
  communication 
  betw 
  r 
  een 
  the 
  two 
  

   ventricles. 
  Between 
  this 
  orifice 
  and 
  that 
  of 
  the 
  left 
  auricle 
  is 
  a 
  large 
  

   and 
  loose 
  valve, 
  so 
  attached 
  as 
  to 
  close 
  them 
  alternately, 
  as 
  it 
  may 
  be 
  

   elevated 
  or 
  depressed 
  precisely 
  upon 
  the 
  same 
  principle 
  as 
  explained 
  

   in 
  reference 
  to 
  the 
  valve 
  of 
  the 
  right 
  ventricle. 
  When 
  this 
  valve 
  is 
  

   elevated, 
  therefore, 
  it 
  exposes 
  the 
  only 
  outlet 
  belonging 
  to 
  the 
  left 
  ven- 
  

   tricle, 
  namely, 
  that 
  passage 
  through 
  the 
  septum 
  which 
  conveys 
  the 
  

   blood 
  into 
  the 
  right 
  ventricle 
  at 
  the 
  roots 
  of 
  the 
  two 
  aortae. 
  The 
  

   right 
  and 
  left 
  aortae 
  unite 
  at 
  an 
  acute 
  angle 
  behind 
  the 
  lungs, 
  and 
  on 
  

   a 
  level 
  with 
  the 
  top 
  of 
  the 
  liver, 
  the 
  left 
  having 
  first 
  passed 
  around 
  the 
  

   oesophagus. 
  The 
  artery 
  that 
  supplies 
  the 
  neck 
  and 
  head 
  is 
  a 
  branch 
  

   of 
  the 
  right 
  aorta, 
  and 
  comes 
  off 
  from 
  it 
  about 
  two 
  inches 
  from 
  the 
  

   heart. 
  

  

  VEINS. 
  

  

  The 
  venous 
  circulation 
  is 
  complicated, 
  and 
  consists 
  of 
  four 
  divisions. 
  

  

  1. 
  The 
  vena 
  cava 
  inferior 
  is 
  constituted 
  of 
  branches 
  coming 
  from 
  the 
  

   kidneys, 
  ovaria, 
  oviducts 
  and 
  liver, 
  being 
  connected 
  with 
  the 
  latter 
  

   organ, 
  as 
  it 
  passes 
  up 
  to 
  the 
  heart, 
  where 
  it 
  unites 
  with 
  the 
  cava 
  su- 
  

   perior, 
  bringing 
  the 
  blood 
  from 
  the 
  head 
  and 
  upper 
  parts 
  of 
  the 
  body. 
  

  

  2. 
  The 
  vena 
  portae 
  commences 
  in 
  the 
  intestine, 
  spleens 
  and 
  stomach, 
  

   by 
  branches 
  which, 
  uniting, 
  form 
  a 
  trunk 
  that 
  passes 
  to 
  the 
  liver, 
  and 
  

   is 
  distributed 
  throughout 
  its 
  structure. 
  3. 
  Another 
  distinct 
  trunk 
  is 
  

  

  