title: The internal jugular vein valve may have a significant role in the prevention of venous reflux: evidence from live and cadaveric human subjects.
abstract: BACKGROUND
  The internal jugular vein valve (IJVV), which is situated just above the termination of the internal jugular vein, is the only valve between the heart and the brain. This means that it plays a role in the prevention of cephalad flow of venous blood. If the IJVV is damaged or becomes incompetent, increase in intrapleural pressure could result in raised intracranial pressure. Additionally, the jugular venous pulse (JVP) is used clinically to estimate right atrial pressure, a functional IJVV may prevent accurate estimation of the JVP.
  
  
  OBJECTIVE
  To describe the presence and the competence of the IJVV in post-mortem and live human subjects. DESIGN - setting and methods: The anatomical appearance of the IJVV from 30 cadavers was studied. Competence was checked by measuring maximum hydrostatic pressure before reflux occurred through the valve. The function of the valve was evaluated in 25 live subjects using colour duplex scanning.
  
  
  RESULTS
  The IJVV was present in all cadavers just before its termination (60 IJVVs from 30 subjects). The valve was bicuspid in most cases (93%). The competence of 41 IJVVs was checked of which only three (7%) were found to be incompetent. All IJVVs in live subjects were found to be competent.
  
  
  CONCLUSIONS
  This study confirms that a functional IJVV is present just above the termination of the internal jugular vein. The IJVV may therefore prevent reflux of venous blood from the right atrium into the internal jugular vein.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Colombo, Sri Lanka. michael1@eureka.lk
authors.forename: M A
authors.initials: MA
authors.lastname: Silva
authors.forename: K I
authors.initials: KI
authors.lastname: Deen
authors.forename: D J S
authors.initials: DJ
authors.lastname: Fernando
authors.forename: A H
authors.initials: AH
authors.lastname: Sheriffdeen
mesh_terms: D000328:Adult; D000368:Aged; D002496:Central Venous Pressure / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D006325:Heart Atria; D006801:Humans; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007601:Jugular Veins / Q000000981:diagnostic imaging / Q000502:physiology*; D008875:Middle Aged; D014463:Ultrasonography