Venous valve

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Cross-section of a vein with cell wall, direction of flow and venous valve
Scheme of a vein.
1 endothelium, 2 venous valves, 3 valvular sinuses.

A venous valve ( lat. Valvula venosa ) is a fold formation in the inner lining ( endothelium ) of the veins . Venous valves consist of two (rarely one or three) crescent-shaped leaflets with an intrinsic connective tissue layer. The sails lie like swallow nests in the lumen , their free edge is directed towards the heart. Venous valves are particularly numerous in those veins in which the blood has to be transported against gravity (e.g. in the legs).

When the blood flows back, the cusps are grasped and close the lumen. Venous valves thus act like a check valve and ensure that the blood only flows in one direction, namely towards the heart (red arrows). Since the blood flow in the veins mainly takes place via external forces acting on the vein (e.g. contractions of the skeletal muscles , muscle pump; black arrow), the venous valves also ensure that the blood does not flow back during the resting phase, but rather step by step is transported towards the heart.

The section of a vein between the valves is called the valvular sinus . He is more extensible than the area of the flap approach, making it for extensions of the veins to perlschnurartigen outgrowths, the " varicose veins " ( varices ), comes.

The venous valves were first described by Giovanni Battista Canano (1515–1579) with his assistant Amato Lusitano , also by Charles Estienne and Jacques Dubois , first researched by Hieronymus Fabricius from Aquapendente , but their importance in the bloodstream was only recognized by William Harvey .

When puncturing extremity veins, the orientation of the venous valves is taken into account by puncturing from distal to proximal .

There are similar valves with the valvulae lymphaticae in the lymphatic system . In contrast to the venous valves, however, they have no musculature, so they function passively. In animals there are "venous valves" sometimes also in arteries , in fish the buccal veins , two folds of the mucous membrane with a valve function for breathing, resemble the venous valves.

Veins without valves

Venous valve prostheses

The Fraunhofer Institute for Manufacturing Engineering and Automation set 2012 venous valve prostheses from polycarbonate - urethane before that were developed there.

See also

literature

  • Uwe Gille: Cardiovascular and immune system, Angiologia. In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. 2nd, revised and expanded edition. Enke, Stuttgart 2008, ISBN 978-3-8304-1075-1 , pp. 404-463.
  • Josef Hyrtl: Textbook of human anatomy with regard to physiological justification and practical application . Wilhelm Braumüller, Vienna 1863, pp. 136-137.

Individual evidence

  1. Jonas Keiler, Marko Schulze, Horst Claassen, Andreas Wree: Femoral vein diameter, valve and tributary topography in humans - a post mortem analysis . In: Clinical Anatomy . tape 31 , 2018, p. 1065-1076 , doi : 10.1002 / ca.23224 .
  2. Wolfgang U. Eckart : History of Medicine. Springer, Berlin / Heidelberg / New York 1990; 3rd, revised edition, ibid 1998, p. 177.
  3. forschungs-blog.de ( Memento from July 30, 2013 in the Internet Archive ).