The cabane struts of a biplane aircraft support the upper wing over the fuselage and work in conjunction with other wing components such as spars and flying wires to transmit flight loads.
In wire-braced monoplanes, e.g. the Blériot XI, the cabane struts (generally referred to as the cabane) form the structure above the wings to which the wing's bracing wires and (if applicable) wing-warping control wires are attached, which were often ventrally attached below the fuselage. In parasol wing aircraft (monoplanes with their wing elevated above the fuselage) the struts carrying the wing are cabane struts; the aircraft may also have a cabane structure for bracing wires. 
Cabane struts also serve to maintain correct wing stagger, angle of incidence and decalage . The initial setting or in-service adjustment of these angles, usually with the help of a clinometer and plumb-bob, is known as 'rigging'. Cabane struts found on early aircraft were often made of wood with later biplanes using aerofoil-sectioned tubular steel.
Occasionally the lower wing of a biplane is placed entirely below the lower surface of the fuselage, using cabane support struts, and such an arrangement could conceivably be called a "ventral cabane strut" assembly. Examples of this arrangement from late World War I are the British Bristol F.2 Fighter two-seat fighter biplane, and the German Pfalz D.XIV experimental fighter, with the 1920s-era Naval Aircraft Factory TS US naval fighter biplane essentially having the same feature.