On Tuesday Rachel Barton Pine announced she will be performing from a seated position for the foreseeable future, on advice from doctors. Fortunately for all of us, her performances as a violin soloist will continue, uninterrupted!
The left hand forms a "scaffolding" that accommodates the fingers, but that shape is formed in the mind and hand of the violinist, not by grabbing anything. Violin technique blog by Paul Stein.