This phenomena has elements of what, in the UK, are termed Phoenix Trees, however this term, and the term Phoenix Regeneration, is more often used when describing characteristics of ancient and veteran trees.
The principles that underlie what the photo shows is that new growth on trees will always grow strongest where there is the most light available, and so in this case as the trunk has become bent towards the canopies, and the shade, of neighbouring trees this branch has become the part of the tree to encounter the most available light.
It is possible to find many trees in a woodland that may show elements of this phenomena; your photo is of a tree that is on the more extreme end of the spectrum for a tree that is still standing. It has developed a different 'dominant' stem to the one it 'started' with.
It is probably not now possible to discover what has happened in the past to cause this tree to bend over in this way; it could have been perhaps a heavy build up of snow or ice at a particularly vulnerable point in its growth, or more likely one or more other trees, or a part of another tree perhaps falling in such a way to knock into it and stay in that position long enough for this tree to adopt this shape in its trunk. If this was the case it may be that the tree/s that fell into it has since been cleared, or decayed away if it was a dead tree or branch.
Often trees that are completely blown over can remain alive because enough roots remain in the soil for it to survive. When this happens the branches on the trunk start to grow upwards into the new space and light that has been created by the tree itself falling. Over time the result is a tree where the main trunk is lying on the ground but the canopy is now a series of branches at right angles heading straight up.
The name for a tree that continues to live and grow after it has fallen over is a "Phoenix tree", named after the mythical bird that regenerates itself after catching on fire; it rises from the ashes.
This term is often applied to old trees, but it could, and does, also be used to describe any tree that has fallen over but continued to grow.
References can be found in Natural England's excellent publication on Veteran and Ancient Tree management
http://publications.naturalengland.org.uk/publication/75035
For example in Chapter 2 "What are Veteran Trees and why are they important?" Section 2.3.4.6 (page 21) of Veteran Trees: A guide to good management
Old trees may fall over completely and then re-grow or collapse and layer well away
from the original base. This is characteristic of lime, willow, alder, black poplar, medlar
and bird cherry but can occur in any species. A particularly notable example is the
Tortworth Chestnut.
The term phoenix regeneration has been applied to trees that have fallen over, or
split apart, and successfully continued growing.
